Design, Synthesis, and Testing of Bis-Corannulene Receptors for Fullerenes Based On

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Design, synthesis, and testing of bis-corannulene receptors for fullerenes based on

Klärner’s tethers

Peumie Luckshika Abeyratne Kuragama

A Dissertation Submitted to the Faculty of Mississippi State University in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy in Chemistry in the Department of Chemistry

Mississippi State, Mississippi

December 2015

Peumie Luckshika Abeyratne Kuragama

2015

Design, synthesis, and testing of bis-corannulene receptors for fullerenes based on

Klärner’s tethers

Peumie Luckshika Abeyratne Kuragama

Approved:

______Andrzej Sygula (Major Professor)

______Keith T. Mead (Committee Member)

______Todd E. Mlsna (Committee Member)

______Dongmao Zhang (Committee Member)

______Stephen C. Foster (Graduate Coordinator/Committee Member)

______R. Gregory Dunaway Dean College of Arts & Sciences

Name: Peumie Luckshika Abeyratne Kuragama

Date of Degree: December 11, 2015

Institution: Mississippi State University

Major Field: Chemistry

Major Professor: Andrzej Sygula

Title of Study: Design, synthesis, and testing of bis-corannulene receptors for fullerenes based on Klärner’s tethers

Pages in Study: 141

Candidate for Degree of Doctor of Philosophy

The discovery of the new allotropic forms of elemental carbon (e.g. fullerenes and

carbon nanotubes) introduced a novel motif in supramolecular chemistry based on

dispersion interactions of curved networks of sp2 hybridized carbon atoms. Buckybowls,

the curve-shaped polycyclic aromatic hydrocarbons, appear to be ideal candidates for

molecular receptors to recognize fullerenes. Corannulene, the smallest and the best

studied buckybowl, has been recognized as one of the important pincers in developing

molecular receptors for fullerenes. The main goal of our research is to synthesize

corannulene-based molecular receptors for fullerenes with high binding affinities with the

use of the pincers preorganized on tailor made tethers of proper topology.

This dissertation describes the design, synthesis, and testing of two bis-

corannulene receptors with Klärner’s tethers. First, molecular mechanics (MM) was

employed for the assessment of the binding potential of the receptors with fullerenes.

Next, the receptors were synthesized by Diels-Alder cycloaddition reactions with

isocorannulenofuran and Klärner’s dienophiles followed by dehydration. Finally, 1H

NMR titrations of both molecular tweezers with fullerenes C60 and C70 were performed.

While the first receptor exhibits the affinity for fullerenes comparable to the previously reported corannulene based receptors, the other with longer, naphthalene based tether, exceeds the performance of the former systems by ca. two orders of magnitude and, in addition, shows an enhanced preference for C70 over C60. These results are in line with the predictions based on MM modeling. The x-ray crystal structure of the 1:1 complex of the larger receptor with C60 indicates that the tether not only preorganizes the pincers into a proper topology to accept the host, but also contributes to the dispersion based binding with the fullerene guests.

Fullerenes and their derivatives are frequently used as electron acceptors in polymer based solar cells. By amalgamation of fullerenes with organic receptors, like the ones reported here, the novel surface bound structures can be constructed with potential applications in nanotechnology and material sciences.

DEDICATION

This dissertation is dedicated to my husband (Saranga Kuragama), parents (Mr

D. A. Abeyratne, Mrs P.G.P. Abeyratne, Mr Sunil Kuragama and Mrs Chandani

Kuragama) and Siblings (Harsha Abeyratne, Gayani Abeyratne, Venuka Jayasundara,

Chamath Perera, Dulip Kuragama and Bimali Senanayake)

ACKNOWLEDGEMENTS

First I wish to express my profound appreciation to my advisor Dr Andrzej

Sygula for all his guidance, support and patience through my years at Mississippi State

University. Your mentorship was paramount in providing a well-rounded experience in

laboratory and I will always be grateful for that. I would especially like to thank Mrs

Renata Sygula for all her help in the laboratory and her support through these years. A special thanks to Dr Michael Yanney for the encouragement and help given in the

laboratory work throughout my PhD.

To my committee members (Dr Stephen C Foster, Dr Keith T. Mead, Dr Todd

Mlsna and Dr Dongmao Zhang) I say thank you for all your support and advice through

my PhD program. I would like to thank my husband for the continuous support and

encouragement provided all this time. Finally to all my friends and lab mates who were

always there for me and I cherish your friendship throughout my life.

iii

TABLE OF CONTENTS

DEDICATION ...... ii

ACKNOWLEDGEMENTS ...... iii

LIST OF TABLES ...... vi

LIST OF FIGURES ...... viii

LIST OF SCHEMES...... xiii

LIST OF ABBREVIATIONS AND CHEMICALS ...... xiv

CHAPTER

I. INTRODUCTION ...... 1

1.1 Fullerene as the Guest Molecule ...... 3 1.2 Receptors for Fullerenes ...... 4 1.3 Molecular Receptors Based on Corannulene Pincers ...... 10 1.4 Thesis Aims ...... 16

II. DESIGN OF BIS-CORANNULENE RECEPTORS BASED ON KLÄRNER’S TETHERS...... 18

2.2 Molecular Receptors with Klärner’s Tethers ...... 22 2.3 Molecular Mechanics Studies as a Screening Tool ...... 23 2.3.1 Conformational Preferences of 33 and 34 and their Binding Energies with Fullerenes ...... 27

III. SYNTHESIS AND CHARACTERIZATION OF BIS- CORANNULENE RECEPTORS BASED ON KLÄRNER’S TETHERS ...... 32

3.1 Synthesis of Molecular Receptor 33 ...... 32 3.1.1 Model Study: Optimization of the Reaction Conditions...... 33 3.1.2 Synthesis of Receptor 33 ...... 36 3.2 Synthesis of Molecular Receptor 34 ...... 41 3.3 Synthesis of Molecular Receptor 34 ...... 43

IV. BINDING STUDIES USING NMR SPECTROSCOPY ...... 51

4.1 Introduction to NMR Spectroscopic Method ...... 51 4.2 Evaluation of the Binding Stoichiometry ...... 54 4.3 Fullerene Binding Studies with Clip 33 ...... 55 4.3.1 Estimation of the Binding Constants of 33 with Fullerene in Toluene-d8 ...... 59 4.4 Fullerene Binding Studies with Clip 34 ...... 61 4.4.1 Binding Studies of Clip 34 with C60 ...... 61 4.4.2 Binding Studies of Clip 34 with C70 ...... 64 4.4.3 Binding Studies of Clip 34 with PCBM ...... 66 4.4.4 Estimations of the Binding Constants of 34 with Fullerenes in Chlorobenzene-d5...... 67 4.5 Crystal Structure Determination for the Inclusion Complex Formation ...... 72 4.6 Potential Applications of Molecular Receptors ...... 76

V. EXPERIMENTAL SECTION ...... 78

5.1 Synthesis of 38 ...... 78 5.2 Synthesis of 33 ...... 81 5.3 Synthesis of Dione 45 ...... 83 5.4 Synthesis of 31 ...... 86 5.5 Synthesis of Molecular Receptor 34 ...... 88 5.6 Synthesis of Starting Materials ...... 91 5.7 1H NMR Titration Experiments for clip 33 ...... 92 5.7.1 Titration of 33 with C60 in toluene-d8 ...... 92 5.7.1.1 Job’s plot for clip 33 with C60 ...... 95 5.7.2 Titration of 33 with C70 in toluene-d8 ...... 96 5.7.2.1 Job’s plot for clip 33 with C70 ...... 99 5.8 1H NMR Titration Experiments for clip 34 ...... 100 1 5.8.1 H NMR titration of 34 with C60 in chlorobenzene-d5 ...... 100 5.8.2 Titration of 34 with C70 in chlorobenzene-d5 ...... 112 5.8.3 Titration of 34 with PCBM in chlorobenzene-d5 ...... 117 5.9 Crystal Structure Determination of C60@34 ...... 120

REFERENCES ...... 137

LIST OF TABLES

MM2 calculated binding energies of C60 with various bis-corannulene clips ...... 29

Reaction conditions attempted for the synthesis of clip 38 ...... 35

Various reaction conditions with p-TsOH ...... 35

Optimization of the reaction conditions for the synthesis of 39 ...... 38

Changes in the chemical shifts of the protons A and B observed in 33 upon addition of C60 and C70 ...... 56

Maximum observed changes in the chemical shifts of selected protons in 34 upon addition of C60 and C70...... 65

Comparison of the binding properties of buckycatchers 23, 29 and 34 in chlorobenzene ...... 72

1 H NMR titration data for C60@33 in toluene-d8 ...... 93

1 H NMR titration data for C70@33 in toluene-d8 ...... 97

1 H NMR titration data for C60@34 in chlorobenzene-d5 ...... 101

1 H NMR titration data for 34 with C60 in chlorobenzene-d5 ...... 107

1 H NMR titration of clip34 with C70 ...... 112

1H NMR Titration of 34 with PCBM ...... 117

Crystal data and structure refinement for C60@34...... 121

Fractional atomic coordinates (×104) and equivalent isotropic 2 3 displacement parameters (Å ×10 ) for C60@34...... 122

2 3 Anisotropic displacement parameters (Å ×10 ) for C60@34 ...... 125

Bond lengths for C60@34 ...... 128

Bond angles for C60@34 ...... 131 vi

Hydrogen atom coordinates (Å×104) and isotropic displacement 2 3 parameters (Å ×10 ) for C60@34 ...... 135

Solvent masks information for C60@34 ...... 136

vii

LIST OF FIGURES

Examples of crown ether, cryptand and spherands ...... 3

Structure of buckminsterfullerene...... 4

Structures of azacrown ether derived macrocycles 5(left), 6(right) and cartoon representation showing their binding with fullerene ...... 5

Structures of β-cyclodextrins, calix-[6]-arenes and a cartoon representation of cyclotriveratrylene derivative with C60 guest on the gold surface ...... 6

Structures of Calix[5]arene receptors 10, 11, 12 & 13 ...... 7

Molecular tweezers 14, 15 and 16 ...... 8

Molecular tweezer 17 ...... 9

Structure of exTTF (left) and molecular receptor 18 (right) ...... 10

Representation of corannulene ...... 11

Chemical structures of compounds 20-22 ...... 12

Synthesis of receptor 24 ...... 13

Representation of the molecular receptor 25 ...... 14

Structures of 26, 27 and 28 ...... 15

Buckycatcher II 29 ...... 16

Representation of the convex and concave structures of corannulene 19 and buckminsterfullerene 4 ...... 20

+ Representation of the complex formed between Li @C60 and corannulene ...... 20

33 Crystal structure of buckycatcher with C60 ...... 21

Klärner’s bis-dienophiles 30 and 31 ...... 22 viii

Structures of Klärner’s molecular receptors ...... 23

Molecular receptor 33 and 34 ...... 24

Structures of 32, 23 and 29 and their C60 inclusion complexes with the calculated binding energies [kcal/mol] ...... 26

Conformers of 33 and 34 and their MM2 calculated relative energies [kcal/mol] ...... 27

Structures of C60@33 and C60@34 and their binding energies [kcal/mol] calculated by MM2...... 28

MM2 binding energies [kcal/mol] of three conformations of C70@34 ...... 31

Molecular receptor 33 ...... 32

APPI MS of 33 ...... 39

1H NMR spectra of 33...... 40

Structure of Klärner’s bis-dienophiles 30 and 31...... 41

Structure of molecular receptor 33 and 34 ...... 42

Space filling representation of the arrangement in C60@34 calculated by MM2 ...... 43

APPI-MS of Molecular Receptor 34...... 48

1 H NMR spectrum for clip 34 in CDCl3 ...... 49

Illustration of the NMR titration ...... 55

1H NMR titration of 600 μL of clip 33 solution with 20 to 1500 μL of C60 solution in toluene-d8 ...... 56

1H NMR titration of 600 μL of clip 33 solution with 20 to 1500 μL of C60 solution in toluene-d8 (aromatic region) ...... 57

Job’s plot for proton A in 33 upon complexation with C60...... 57

1H NMR titration of 600 μL of clip 33 solution with 20 to 1500 μL of C70 solution in toluene-d8 ...... 58

Job’s plot for proton A in 33 upon complexation with C70...... 58

Nonlinear curve regression of the titration of 33 with C60 ...... 60 ix

Nonlinear curve regression of the titration of 33 with C70 ...... 60

1H NMR titration of 600 μL of clip 34 solution with 10 to 1500 μL of C60 solution in toluene-d8 ...... 62

Job’s plot for proton 3 in 34 upon titration with C60 ...... 63

1H NMR spectrum of the symmetry independent aromatic protons of 34 in chlorobenzene-d5 ...... 63

Changes in the chemical shift of protons in clip 34 upon successive addition of C60 in chlorobenzene-d5 ...... 64

Job’s plot for proton 5 (at 7.90 ppm, Figure 4.11 and Table 5.5) in 34 upon titration with C70 ...... 65

Changes in the chemical shifts of protons in clip 34 upon successive addition of C70 in chlorobenzene-d5 ...... 65

The structure of PCBM (50) ...... 66

Job’s plot for proton at 3.9 ppm in 34 with PCBM ...... 67

Changes in the chemical shifts of protons in clip 34 upon successive addition of PCBM in chlorobenzene-d5. 600 μL of clip 34 solution with 10-1500 μL of PCBM solution...... 67

Nonlinear curve regression of the titration of 34 with C70 ...... 70

Crystal arrangement in C60@34 (left) and Crystal packing pattern seen along a crystallographic axis (right)...... 73

APPI-MS of C60@clip 34 1:1 inclusion complex formation ...... 74

APPI-MS of C70@clip 34 1:1 inclusion complex formation ...... 75

1H NMR spectrum of 38 ...... 80

13C NMR spectrum of 38 ...... 80

APPI-MS of 38 ...... 81

APPI-MS of 33 ...... 82

1H NMR spectrum of 33 ...... 82

13C DEPT-Q135 NMR spectrum of clip 33 ...... 83

1H NMR spectrum of dione 45 ...... 84

13C NMR spectrum dione 45...... 85

ESI MS of dione 45...... 85

1H NMR spectrum for 31 ...... 87

13C NMR spectrum for compound 31 ...... 87

ESI MS of 35 ...... 88

1H NMR spectrum of clip 34 ...... 89

13 C DEPTQ135 NMR of 34 (150 MHz, CDCl3) ...... 90

APPI-MS of clip 34 ...... 90

Synthetic outline for dienophile 30 ...... 91

Synthetic outline for dienophile 31 ...... 92

Jobs plot for protons A(left) and proton B (right) for the titration of 33 with C60 ...... 95

Nonlinear curve regression of the titration of 33 with C60 ...... 96

Job’s plot for proton A (left) and B (right) fot the titration of 33 with C70 ...... 99

Nonlinear curve regression of the titration of 33 with C70 ...... 100

Job’s plot for protons 3 (left) and OMe (right) for the titration of 34 with C60 ...... 106

Job’s plot for protons 4 (left) and 5 (right) for the titration of 34 with C60 ...... 106

Nonlinear curve regression of the titration of 34 with C60 (Failed attempt) ...... 107

Job’s plots for protons 5 (left) and 11 (right) for the titration of 34 with C70 ...... 115

Job’s plots for protons 9 (left) and 10 (right) for the titration of 34 with C70 ...... 116

Nonlinear curve regression of the titration of 34 with C70 ...... 116 xi

Nonlinear curve regression of the titration of 34 with C70 ...... 116

xii

LIST OF SCHEMES

1.1 Synthesis of molecular receptor 23 ...... 12

3.1 Synthesis of tether 30 ...... 33

3.2 Synthesis of phenanthro[9,10-c]furan 36 ...... 34

3.3 Synthetic approach for clip 38 ...... 34

3.4 Synthesis of molecular receptor 38 ...... 36

3.5 Synthesis of Isocorannulenofuran ...... 37

3.6 Improved synthesis of the cycloadduct 39 ...... 38

3.7 Synthesis of molecular receptor 33 ...... 39

3.8 Two synthetic routes to synthesize 31 ...... 44

3.9 Synthesis of diene 41 ...... 45

3.10 Alternative synthesis of diene 41 ...... 45

3.11 Synthesis of 43 and 45 ...... 46

3.12 Synthesis of 45 and 49 ...... 47

3.13 Modified Synthesis of 31 from 44 ...... 47

3.14 Synthesis of the molecular receptor 34 ...... 48

xiii

LIST OF ABBREVIATIONS AND CHEMICALS

DNA Deoxyribonucleic acid exTTF Extended Tetrathiafulvalene

DCM Dichloromethane

DMSO Dimethylsulfoxide

Diglyme 1-Methoxy-2-(2-methoxyethoxy)ethane

DMF Dimethylformamide

DME Dimethoxyethane

IR Infrared Spectroscopy

TEA Triethylamine

MeOH Methanol

DDQ 2,3-dichloro-5,6-dicyano-1,4-benzoquinone

LiAlH4 Lithium aluminium hydride

MS Mass Spectrometry

FVP Flash Vapour Pyrolysis

MM Molecular Mechanics

NMR Nuclear Magnetic Resonance

DBU 1,8-Diazabicyclo[5.4.0]undec-7-ene

xiv

PCBM 1-3(-(methoxycarbonyl)propyl)-1-phenyl[6,6]C61 o-DCB o-dichlorobenzene

MM2 Molecular Mechanics Method II

Ka Association Constant

G Guest Molecule

H Host Molecule

APPI-MS Atmospheric Pressure Photoionization Mass Spectrometry BE Binding Energy

CHAPTER I

INTRODUCTION

Supramolecular chemistry is considered as the “chemistry beyond the molecule”.

Traditional chemistry mainly concentrates on the chemical bonds that hold the elements together in a molecule while supramolecular chemistry focuses on the interactions that hold the group of molecules together. The intermolecular forces responsible for the assembly of the components fall mainly into three categories such as electrostatic, dipole induction, and dispersion interactions.1-3 Electrostatic effects arise from the interactions

between the static charge distributions of the two molecules. Hydrogen bonding is a

special case electrostatic attraction between polar molecules that occurs when a hydrogen

atom bound to a small highly electronegative atom (nitrogen, oxygen or fluorine) experiences attraction to some other nearby electronegative atom. Inductive effects arise when the charge cloud of a molecule is distorted by the presence of another polar molecule nearby. Dispersion interactions, on the other hand, arise from instantaneous dipole and induced dipole interactions.

The term supramolecular chemistry started to appear in 1890s. The concept was first proposed by Fischer when he suggested that enzyme-substrate interactions take the

form of a “lock and key” combination, mounting the idea of molecular recognition and

host-guest chemistry.4 At the beginning of the twentieth century scientists started to

understand the nature of the non-covalent bonds in more detail. This resulted with the discovery of hydrogen bonds by Latimer and Rodebush in 1920.5

When representing the power of self-assembly, nature is undeniably the greatest source of inspiration for the scientific community. There are several examples of self- assembly in biological systems and DNA is one of them, existing as a double helical form.6 Two separate strands of DNA are held together by a number of hydrogen bonds

and stacking forces in order to maintain the helical structure. Owing to the relatively

weak non-covalent interactions, the strands in DNA are able to break apart and reform

easily through supramolecular interactions.

By considering these natural systems, scientists began to design and study

synthetic structures based on non-covalent interactions. The first major discovery in this

area came in the 1960s when Pedersen discovered compounds now known as “crown

ethers” (1, Figure 1.1) acting as host molecules to alkaline metals cations.7 Different

alkali metal ions bind with these compounds depending on the size and shape of the

cavity. The next significant step in the area of host-guest chemistry was the introduction

of cryptates (2).8 These molecules, designed by Lehn, are three dimensional analogues of

crown ethers. They bind with guest molecules more strongly and selectively than crown

ethers. Subsequently, spherands (3), calixarenes and resorcinarenes, ion and shape

selective receptors were introduced by Cram.9-11

Examples of crown ether, cryptand and spherands

The significance of supramolecular chemistry was recognized by the 1987 Nobel

Prize awarded to Cram, Lehn and Pedersen. Supramolecular chemistry became even

more advanced in the 1990s with the introduction of molecular machinery and complex

self-assembled structures by Stoddart.12 During this period electrochemical and

photochemical functionalities were also integrated into supramolecular systems in order

to increase the functionality of the host-guest assemblies.13 Supramolecular chemistry is

closely related to nanotechnology, and many nanotech devices are based on the principles

of supramolecular chemistry.

1.1 Fullerene as the Guest Molecule

Fullerenes, the new allotropic forms of carbon, were discovered in mid 1980s.14

The discovery earned Kroto, Curl, and Smalley a Nobel Prize in 1996. The most studied

member of this family is buckminsterfullerene C60 (4, Figure 1.2), which contains 12 pentagonal and 20 hexagonal rings.14 All sixty carbon atoms are identical by symmetry and each carbon atom exhibits sp2 hybridization. These nanoscale cage molecules have

curvature induced by the presence of pentagonal rings embedded into the network of six-

membered rings. Therefore, they have of a weak local polarization on their surfaces between the 5:6 ring junctions, which represent centers of positive charge and the

negatively charged 6:6’ junctions.14,15 Of course, due to its symmetry, the entire molecule of C60 has a dipole moment of zero.

Structure of buckminsterfullerene

There has been a great interest in developing molecular receptors for fullerenes, due to their distinctive chemical and physical properties (electronics, conductivity, magnetism, etc.) which have promised their applications in material sciences.16

1.2 Receptors for Fullerenes

Since the extraction of fullerenes from the carbon soot in 1990 by Krätchmer and

coworkers, the interaction between fullerenes and receptor molecules has received increasing attention.17 There are two main reasons to design molecular receptors and

tweezers for fullerenes: on one side, it would allow for an effective purification and

separation of fullerenes of different sizes from their extraction sources. On the other

hand, in amalgamation of fullerenes with these receptors, we could develop structured

designs that can find potential application in photoelectronics. Also the organization of

the receptors on the solid surfaces plays a vital role in the enhancement and specific operations of the nano-devices.

When considering the features of the forces existing in the assembly and the nature of fullerenes, van der Waals and solvophobic interactions can be considered vital for the stability of the fullerene-receptor complexes.18 The first successful example of a

molecular receptor for fullerene was reported by Ringsdorf, Diederich, and co-workers.19

The molecular receptors that they have synthesized were aza-crown ethers, to which the

lipophilic alkyl chains were attached (Figure 1.3). It was shown that fullerenes are

incorporated in to the non-polar cavities of azacrown ethers such as 5 and 6 (Figure 1.3).

Structures of azacrown ether derived macrocycles 5(left), 6(right) and cartoon representation showing their binding with fullerene

Subsequently, other macrocyclic motifs including cyclodextrins20 (7),

cyclotriveratrylenes21 (9), and calixarenes22 (8) have been utilized in the recognition of

fullerenes (Figure 1.4).

Structures of β-cyclodextrins, calix-[6]-arenes and a cartoon representation of cyclotriveratrylene derivative with C60 guest on the gold surface

The main motif behind these receptors is that the fullerene binds in the lipophilic cavity and the hydrophobic addends that are bound to the macrocycle adapt to the size of the guest. This concept will basically take the benefit of the low solubility of fullerenes in most solvents. The solid state crystallographic analysis of these traditional complexes show the importance of π-π interactions of fullerenes with the concave surfaces of the hosts.

Fukazawa and coworkers introduced the efficient molecular receptors for fullerenes based on OH-calix[5]arenes (10-13, Figure 1.5).23 The association constants increase in solvents, where the solubility of C60 decreases, showing the vital role played by the solvophobic forces in these type of interactions. The highest Ka was observed for

10 which contains two iodine atoms in the periphery with the binding constant of 2120

M-1 in toluene. Receptors 11 and 12 which possess smaller substituents showed lower

-1 binding affinity with C60 (Ka ~ 1700 and 600 M , respectively).

Structures of Calix[5]arene receptors 10, 11, 12 & 13

Fukazawa and coworkers proved that calix[5]arene 13 forms a 1:1 complex with

C60 in solution. However, from the x-ray crystalline studies it was confirmed that 2:1

complex C60@132 exists in the solid state.

The classical receptors based on calixarenes, cyclotriveratrylenes and

cyclodextrins are designed in a way where the fullerene guests are incorporated into the

lipophilic cavities of the macrocycles. A special approach in the design of molecular

receptors for fullerenes is to employ two or more units of organic molecules that can act

as pincers and to link them through a spacer or a tether. This designed architecture is also

termed molecular tweezers.24,25 In an attempt to improve the affinity of these receptors

for fullerenes two strategies have been proposed. First is to incorporate electron rich

aromatic units as pincers in the host. Second is to preorganize the pincers on a sterically

rigid tether(s). Organic molecules that preferably match this design include large aromatic compounds which can interact with the fullerenes through π−π stacking.

Molecular tweezers 14, 15 and 16

Fukazawa and coworkers have synthesized bis-calix[5]arene molecular tweezers

(Figure 1.6).26,27 In this design two units of calix-[5]-arenes (pincers) were covalently

attached through different tethers. Among the calixarene dimers, 15 shows the highest

affinity for C60, significantly higher than the monomeric receptors 10-13. Binding studies also confirmed that receptors 14-16 bind C70 more selectively than C60.

A series of porphyrins based tweezers have been reported up to date. One of the

“jaws” receptors synthesized by Boyd and Read is shown in Figure 1.7.28 The porphyrin

units in 17 are linked through a Pd metal center. The association constant between clip

3 -1 17 and C60 was determined to be 5.3 x 10 M in toluene-d8 at room temperature.

Molecular tweezer 17

The systems with curved conjugate units such as 2-[9-(1,3-dithiol-2- ylidene)anthracen-10(9H)-ylidene]-1,3-dithiol (ex-TTF, Figure 1.8) have shown stable inclusion complex formation with fullerenes, both in solution and in solid state.29

Structure of exTTF (left) and molecular receptor 18 (right)

Recently few groups have designed receptors for fullerenes using exTTF as

pincers (Figure 1.8).30 A shape complementarity between the concave aromatic face of ex-TTF and the convex face of fullerenes is expected to lead to large noncovalent interactions. Receptor 18 was prepared by Martin et al with two ex-TTF pincers and

isopththalate diester spacer. UV – vis studies provided the binding constant of (3.0 ± 0.2)

3 -1 x 10 M in chlorobenzene at room temperature. The significant stability of the C60@18

complex suggests that ex-TTF is an effective pincer for fullerene recognition.

1.3 Molecular Receptors Based on Corannulene Pincers

As discussed in the previous section, the curved nature of molecules employed as

pincers provides the wide contact with fullerenes and results in effective binding.

Another example of the curved conjugate units are buckybowls, the bowl shaped 10

polycyclic aromatic hydrocarbons which appear to be ideal candidates for molecular receptors with the ability to recognize fullerenes through concave-convex “ball-and-

socket” π-π interactions.31 Corannulene (19, Figure 1.9) is the smallest and best studied buckybowl.

Representation of corannulene

Synthesis of corannulene based receptors for fullerenes was first attempted by

Mizyed et al (Figure 1.10).32 These systems were tested for their abilities to form

supramolecular complexes with fullerenes. Binding studies using NMR titration experiments (in toluene) provided a moderate association constant for C60@22 (1420±54

-1 M ). Other corannulene based derivatives 20 and 21 showed relatively low Ka values.

The higher association constant for C60@22 was attributed to the electron donating

groups in 22, which most likely interacted favorably with the electron deficient convex surface of C60 rather than the corannulene subunit.

Chemical structures of compounds 20-22

The first example of a successful receptor for fullerenes based on corannulene

was synthesized by Sygula et al. and it is termed “buckycatcher” (23).33 This molecular

receptor consists of two corannulene pincers linked through a

tetrabenzocyclooctatetraene tether. The synthesis of molecular receptor 23 is outlined in

scheme 1.1. Molecular tweezers 23 form stable inclusion complexes with C60 (Ka = 2780

-1 -1 ± 80M , in toluene-d8, and 520 ± 20M in chlorobenzene-d5 at room temperature).

C60@23 inclusion complex was also characterized by X-ray crystallography.

Scheme 1.1 Synthesis of molecular receptor 23

Another example of a molecular receptor with corannulene pincers synthesized in our group is 24 (Figure 1.11), with a cyclotriveratrylene tether and three corannulene

34 1 pincers. H NMR titration experiments in toluene-d8 suggested the formation of 1:1

fullerene@24 complexes and provided the association constants of 1500 ± 50 and 1180 ±

-1 30 M for C60 and C70 respectively. Notably, 24 has a lower affinity for fullerenes as compared to 20, even though 24 has an additional corannulene pincer able to bind with

the fullerene surface. The lower binding affinities of 24 with fullerenes were explained

by more severe entropy and solvation penalties associated with the supramolecular

assembly formation in solution.

Synthesis of receptor 24

Another type of a corannulene based tweezers 25 (Figure 1.12) was synthesized

by Alvarez et al.35 The complex consist of 1,2-bis(diphenylphosphino)ethane ligand

(dppe) and two polyaromatic ethynyl units coordinated to a platinum metal center forming a square planar complex. This receptor displays a high binding affinity for C70

-1 around 20,700 ± 600 M in toluene-d8 and a moderate binding affinity for C60.( Ka = 13

-1 4600 ± 100 M in toluene-d8). This shows tweezers 25 has a higher selectivity for C70

over C60.

Representation of the molecular receptor 25

Another group of corannulene based receptors for fullerenes was recently reported by Alvarez et al. (Figure 1.13).36 These systems were synthesized using “click

chemistry” between ethynylcorannulene and various azides. From binding studies it was

confirmed that the three-armed derivatives 26 and 27 show some affinity for C60 ( Ka =

(2.15 ± 0.30) × 103 M−1 and (2.19 ± 0.05) × 103 M−1, respectively). Compound 28, having two corannulene subunits linked to a hexahelicene has a binding affinity of (2.55

± 0.14) ×103 M-1. Interestingly, all three molecular receptors exhibit almost identical

affinities toward C60.

Structures of 26, 27 and 28

Yanney and Sygula recently synthesized buckycatcher II (29, C51H24, Figure 1.14)

with two corannulene pincers on a dibenzonorbornadiene tether which shows a dramatic

4 increase in the binding affinity towards C60 ( 퐾1 = (1.0 ± 0.1) × 10 , 퐾1 =

3 (1.2 ± 0.6) × 10 in chlorobenzene-d5) in comparison with the other corannulene based

37 molecular receptors. This receptor forms a usual 1:1 C60@29 inclusion complex, as

well as a trimeric C60@ (29)2 assembly, as detected in solution and in the solid state.

Buckycatcher II 29

In this introduction we have discussed various types of receptors for fullerenes

synthesized up to date and their corresponding binding affinities. We have incorporated

some of the concepts in designing and synthesizing the bis-corannulene based receptors

described in this thesis to improve the affinity for fullerenes.

1.4 Thesis Aims

The main goal of our research group is to construct corannulene-based molecular

receptors for fullerenes with high binding affinities, where the pincers are preorganized

on tailor-made tethers of proper topology. In this thesis we describe the design, synthesis

and testing of bis-corannulene receptors based on tethers introduced by Klärner. The

tethers have a syn configuration of the two methylene bridges in the bis-dienophiles, and, in addition, they possess substituents which offer a possibility for further chemical modifications to satisfy the requirements for an efficient attachment of the clips to the solid surfaces by a linker of the required length. These are the first types of corannulene containing molecular tweezers with such substituents on their tethers synthesized in our

group.

In Chapter II we discuss the design of two receptors with Klärner’s tethers using molecular mechanics calculations. The calculated binding energies of the designed receptors with C60 are compared with the binding energies of the existing systems to

evaluate their potential to act as molecular receptors.

Chapter III focuses on the synthesis of two bis-corannulene receptors with

Klärner’s tethers previously studied by molecular mechanics.

Chapter 1V describes the binding studies performed on the synthesized receptors

1 with fullerenes C60, C70 and PCBM using H NMR titrations. We also describe the crystal structure of the inclusion complex C60@34.

CHAPTER II

DESIGN OF BIS-CORANNULENE RECEPTORS BASED ON KLÄRNER’S

TETHERS

As discussed in Chapter I, the high affinity of a molecular clip or tweezers towards a given guest molecule depends on two factors, i.e. (1) strong and specific interactions of the pincers with the guest and (2) a proper preorganization of the pincers by the tether into a required topology. The discovery of fullerenes and other forms of elemental carbon with curved surfaces introduced a novel aspect of supramolecular assembly based on the dispersion forces between the convex surface of the conjugated

carbon networks and the appropriate molecular receptors. From that perspective

buckybowls,38-40 the curved surface polyaromatic hydrocarbons (PAH) structurally related to fullerenes, appear to be good candidates for the pincers due to the complementary of their accessible concave surfaces with the convex surfaces of the carbon cages.31,33

The term molecular tweezers was first introduced in 1978 by Chen and Whitlock who designed molecular receptors with caffeine pincers that act as hosts for planar π conjugated molecules.24 They also defined the three features necessary for an efficient

molecular receptor to be able to form inclusion complexes. (a) Spacers should prevent

intramolecular self-association of the pincers, (b) a proper distance between pincers to

accommodate the host, and (c) ideally, spacers should enforce a syn orientation of the 18

pincers. Generally, these requirements have been the guiding principles in the design of molecular receptors.

Before the discovery of fullerenes almost all reported molecular clips employed planar pincers. Interest in molecular receptors with corannulene pincers arose because the concave surface of 19 could align perfectly to the convex surface of fullerenes (4)

(Figure 2.1). The gas phase binding energy for C60@19 supramolecule predicted by B97-

41 •+ D/TZVP calculations is 19.5 kcal/mol. Interactions between corannulene and C60 in

42 the gas phase have been detected using MS. Only recently Dawe et al have succeeded

in obtaining the X-ray structures of both 1:1 C60@corannulene co-crystals and of

43 C60@penta-t-Bu-corannulene. A scanning tunneling microscopy (STM) study provided

the evidence for the formation between corannulene and C60 complexes on Cu(110)

surface.44

Although gas phase and solid phase studies show inclusion complex formation of

C60 and corannulene, a significant binding for supramolecular assemblies of C60 with the

smallest buckybowl corannulene (19) have not been detected in solution. As discussed in

Chapter 1, some corannulene derivatives bearing electron rich arms have shown moderate

-1 association constants with C60 in the range of 60 – 1400 M , which arguably are mostly

due to the rim substituents-fullerene interactions.32,45 In 2014 Fukuzumi et al detected a

+ charge transfer complex formed between lithium ion-encapsulated fullerene (Li @C60)

-1 46 and corannulene with a small binding constant Ka = 19 M in benzonitrile (Figure 2.2).

In addition, the association constant for pristine C60 and corannulene in benzonitrile was

estimated to be ≪ 1 M-1 by the same authors, significantly lower than what they observed

+ for 19/Li @C60. These results suggest that the attractive dispersion interaction of a

single corannulene bowl with the convex surface of fullerene cage is insufficient to overcome the expected entropy and solvation penalties associated with the dimeric complex formation.18

Representation of the convex and concave structures of corannulene 19 and buckminsterfullerene 4

+ Representation of the complex formed between Li @C60 and corannulene

While the attractive forces between the concave-convex surfaces of one corannulene molecule and C60 are not that significant in solution, it has been shown that the efficient molecular receptors for both C60 and C70 can be constructed if at least two

corannulene pincers are preorganized on a proper tether. The experimental evidence of

the inclusion complex formation of C60 with buckycatcher C60H28 (Figure 2.3)

synthesized by Sygula et al. proves that the binding dispersion interactions between

fullerene guest and two corannulene pincers of the clip are strong enough to induce the

exergonicity of the association, even in relatively strongly solvating solvents.33,47

33 Crystal structure of buckycatcher with C60

As discussed in section 1.3, there are handful of receptors with two or three

corannulene subunits that have been recently synthesized and tested as potential receptors

for fullerenes. Most of these receptors show binding affinities for fullerenes in the range

of 1500-5000 M-1 in toluene. Our main objective is to design molecular clips with

corannulene pincers forming stronger inclusion complexes with C60 and C70 than the

existing corannulene receptors.

2.2 Molecular Receptors with Klärner’s Tethers

Klärner’s bis-dienophiles 30 and 31

Klärner et al. have synthesized molecular tweezers with the tethers 30 and 31

(Figure 2.4) with various planar aromatic pincers.48,49 Some of the synthesized receptors

are shown in Figure 2.5.49-52 These molecules are constructed to recognize smaller

aromatic compounds. Tethers 30 and 31 show the significance of the preorganization of

the pincers in the required syn topology.50,53 Additionally, these offer extra π-π

interactions with aromatic guests. The presence of methoxy substituents on the aromatic

spacers offers a possibility for further chemical modifications to satisfy the requirements

for an efficient attachment of the clips to solid surfaces or convert them to water soluble

substances.51,53 Although the Klärner’s dienophiles have unique features for design of

receptors, the use of them by other research groups has been very limited most probably

due to the tedious multistep synthetic procedures and their relatively low reactivity with

dienes.

Structures of Klärner’s molecular receptors

2.3 Molecular Mechanics Studies as a Screening Tool

The trial and error approach to the design and synthesis of molecular receptors or

tweezers includes sometimes accidental selection of spacers and pincers that appear

likely to provide the efficient binding of selected guest molecules, then synthesizing the

molecular clips followed by testing their binding affinities in solution. This approach is

expensive and tedious. Hence we proposed the “intelligent design” of molecular

receptors and tweezers in which the potential of a chosen receptor can a priori be

evaluated. Computational methods which are capable of calculating the binding energies

(BE) of supramolecular assemblies with reasonable accuracy offer an alternative

approach which would allow for a quick screening of a pool of possible pincer-tether

combinations. The most promising candidates are then selected, synthesized and tested.

Molecular receptors 33 and 34 (Figure 2.6) described in this thesis were tested for

their binding affinities with fullerenes by molecular mechanics (MM) methods. MM

method is a fast and inexpensive computational approach used to determine the binding

energies of the inclusion complexes.54 Despite the fact that MM methods suffer from several limitations and drawbacks they recognize van der Waals nonbonding attractions that play an important role in these molecular assemblies.

Molecular receptor 33 and 34

Our strategy is to compare the MM results of clip 33 and 34 with a series of

existing similar assemblies to provide useful information about trends rather than to

supply exact binding energies. Binding energy is calculated as the difference between the

strain energies (SE) of the substrates (the separated host and guest molecules) and the

product (the supramolecule) in the gas phase. This number is related to the −ΔH of the complex formation in gas phase. When the clip has a number of distinct conformers, the strain energy of the most stable conformer is chosen and the binding energy is calculated by Equation 2.1.

퐵퐸 = (푆퐸퐻 + 푆퐸퐺) − 푆퐸퐻퐺 (2.1)

Where;

BE Binding Energy of the complex

SEHG Calculated strain energy of the complex

SEH Calculated strain energy of the host

SEG Calculated strain energy of the guest

There are two more factors that affect the free energy of association (ΔG0) in solution, i.e. solvation effects and entropy changes. These factors act against the complex formation but should be similar in a series of structurally related systems.

Hence the larger the gas phase binding energy of the assembly is, the more likely it is to observe the complex formation in solution.

We first tested this approach on the previously studied pincers. MM2 calculated binding energies for C60@32, C60@23 and C60@29 are 17.5, 23.5 and 26.0 kcal/mol respectively (Figure 2.7).

Structures of 32, 23 and 29 and their C60 inclusion complexes with the calculated binding energies [kcal/mol]

Experimentally 32 failed to exhibit any significant association with C60, but

33,37,55 buckycatchers 23 and 29 showed strong bindings with C60. The experimentally

determined differences in their complexing capabilities are reflected in the calculated

binding energies, since C60@23 and C60@29 have the binding energies higher by ca. 6.5

and 9 kcal/mol, respectively, than C60@32. Also, the experimentally determined ten-fold increase of the fullerene binding affinity of 29 over 23 is reflected in their calculated

binding energies, where C60@29 has the binding energy higher by 2.5 kcal/mol than

C60@23.

Apparently, MM2 screening can be applied to assess the binding potential of bis-

corannulene receptors in solution. We therefore employed the MM2 calculations to

assess the binding potential of receptors 33 and 34.

2.3.1 Conformational Preferences of 33 and 34 and their Binding Energies with Fullerenes

Conformers of 33 and 34 and their MM2 calculated relative energies [kcal/mol]

The molecular mechanics calculations performed with MM2 display that in the

gas phase 33 can exist in three different conformations (Figure 2.8) which can be

described by the relative topology of their corannulene pincers as concave-concave (33a), concave-convex (33b), and convex-convex (33c). These can interconvert quickly due to the relatively low energy barrier for the bowl-to-bowl inversions of the corannulene fragments.56 Due to the relatively short tether in 33 the corannulene fragments can interact by dispersion forces. This results in the desired open conformation 33a

significantly less stable than the closed 33b. The closed conformer is stabilized by the

efficient concave-convex π-π stacking of the corannulene surfaces and represents the 27

global potential energy minimum of 33 in the gas-phase. It has to be taken in to account

that the open conformations are predicted to be strongly favored by solvation due to their

significantly larger solvent accessible surfaces. Nevertheless a substantial gas phase

preference for 33b suggests that this conformation may compete with the open

conformations even in solutions, potentially decreasing the ability of 33 for hosting the

guest molecules.

Open conformations 34a-34c (Figure 2.8) have relative stabilities differing by less

than 0.4 kcal/mol. However we still found the closed concave-concave 34d as the most

stable conformer. In this case the gas phase closed conformer is only slightly more stable

than the open conformations and this preference can likely be reversed in solutions.

Structures of C60@33 and C60@34 and their binding energies [kcal/mol] calculated by MM2

From the trend that we observed in the MM2 calculated binding energies (Table

2.1) of 32, 23 and 29 with C60 we can get a good approximation whether the clips 33 and

34 are potentially better candidates for fullerene recognition.

MM2 calculated binding energies of C60 with various bis-corannulene clips

C60@ 32 23 29 33 34

BE 17.5 23.5 26 17.6 29 [kcal/mol]

The MM2 calculated binding energy of C60@33 (Figure 2.9) is lower than

buckycatcher 23, but the calculated binding energy for C60@34 (Figure 2.9) is

significantly higher than for the efficient clips, buckycatcher 23 and 29 ( Table 2.1).

Hence we expect that the inclusion complexes of C60 with 34 should be easily formed and

detected in solution. While the gas phase binding energy of C60@33 is lower than of

C60@23, we still decided to prepare it expecting that the functionally modified 33 will

form inclusion complexes with other guest molecules. Water soluble receptors with

similar tethers synthesized by Klärner et al. exhibit significant affinity for guests including various amino acids.52 Apparently these studies have led to the expectation that

33 with various modified substituents will act as potential receptors for biologically

active guests.

The qualitative trends in the MM2 gas phase binding energies of C60 with the

studied clips are reproduced nicely when using more sophisticated B97-D/TZVP//B97-

D/QZVP calculations,57 supporting the employment of an inexpensive MM2 methods for

the fast screening of the potential molecular receptors. (dispersion corrected DFT calculations were done by Sygula)37,58

The differences in the binding affinities of the two clips 33 and 34 to C60 can be

explained by a closer look at the minimum energy conformers. When considering 33, the

clip deformation penalty (i.e. the energy difference between the minimum energy

conformer of the isolated clip and the conformation of the clip in the complex) is

calculated to be quite significant (11.4 kcal/mol). The proximity of the corannulene

pincers in 33 brings a possibility of an existence of a stable closed π-π stacked conformer

33b which, if present in solution, could diminish the binding energies of the inclusion

complexes. On the other hand, even though the MM2 and B97-D/TZVP calculations find

the closed conformation 34d to be the lowest energy conformation in the gas phase, it is

only slightly preferred over the open conformer 34. The calculated clip deformation

penalty for 34 is 4.2 kcal/mol only, significantly lower than calculated for 33. This can

explain, at least in part, the significantly stronger binding of C60 by the former receptor.

We also tested the binding ability of 34 with C70. MM2 calculations located three

orientations in which the C70 can align within the clip. From these the highest binding is

found when the C70 is aligned vertically as shown in Figure 2.10. Notably, the molecular

modeling calculations show higher affinity of 34 towards C70 as compared to C60. The

gas-phase binding energy calculated for C70@34 inclusion complex (30.2 kcal/mol) is 1.2

kcal/mol higher than that of C60@34. Assuming that both the solvation and entropy penalties associated with the supramolecular complex formation are comparable in the two cases, we predict that the stronger dispersion-based attraction of C70 by 34 will result

in the more exergonic thermodynamics of the C70@34 complex formation.

MM2 binding energies [kcal/mol] of three conformations of C70@34

According to MM2 studies clip 33 shows a lower binding energy for fullerenes as compared to the original bucycatcher 23. The high deformation penalty calculated by

MM2 explains the low affinity of 33 towards C60. In contrast, clip 34 with the naphthalene based tether shows a remarkable MM2 gas phase binding energies for fullerenes and is expected to be the best corannulene based receptor designed up to date.

CHAPTER III

SYNTHESIS AND CHARACTERIZATION OF BIS-CORANNULENE RECEPTORS

BASED ON KLÄRNER’S TETHERS

3.1 Synthesis of Molecular Receptor 33

Although 33 (Figure 3.1) in the gas phase shows a lower binding affinity with fullerenes compared to the original buckycatcher 23, we attempted the synthesis of the clip expecting that it will be a good receptor for other guest molecules. As stated in

Chapter III, water soluble receptors with Klärner’s tethers exhibited significant binding affinities for various amino acids.52 Likewise, we expect that 33 with various modified substituents will act as potential receptors for biologically active guests.

Molecular receptor 33

Molecular receptor 33 (Figure 3.1) was synthesized by Diels-Alder reactions between Klärner’s bis-dienophile 30 and isocorannulenofuran (40). Bis-dienophile 30

was prepared by following the procedure developed by Klärner et al. The synthesis is

outlined in scheme 3.1.48

Scheme 3.1 Synthesis of tether 30

3.1.1 Model Study: Optimization of the Reaction Conditions

Considering the high cost of synthesis of isocorannulenofuran we decided to optimize the Diels-Alder reaction conditions on a model reaction substituting 40 with phenanthro[9,10-c]furan 36, which was synthesized using the procedure developed by

Wege et al. (Scheme 3.2).59

Scheme 3.2 Synthesis of phenanthro[9,10-c]furan 36

Scheme 3.3 Synthetic approach for clip 38

Various reaction conditions were tested as reported in Tables 3.1 and 3.2. DMSO and diglyme were the only solvents working for the Diels-Alder cycloaddition step, which requires high temperatures to produce the cycloadducts (scheme 3.3).

Temperature ranging between 120 and 200 0C were applied for the double Diels-Alder

cycloaddition step in DMSO and diglyme. In an effort to improve the yields of the reaction we have attempted the synthesis of the cycloadducts in a microwave reactor

(Table 3.1).

Reaction conditions attempted for the synthesis of clip 38

Solvent Temperature for D-A Rn Time/h p-TsOH 800C Product 38 D-A Rn/ 0C Time /h %Yield DCM 60 24 - ab DME 85 24 - a Toluene 110 24 - a Tetrachloroethane 170 24 - ab DMF 150 24 - a Diglyme 200 24 48 30%b DMSO 190 24 48 55% *DMF 200 2 - a *Diglyme 200 2 3 25% *DMSO 200 2 3 30% a – no reaction, b – pressurized closed vial, * - microwave reactions

Without separation of the mixture of cycloadducts the dehydration step was

performed after the completion of the first step as evidenced by TLC and 1H NMR.

Various acids were tried for this reaction (p-TsOH, H2SO4 and HCl), but 38 was formed

only in the presence of p-TsOH at 80 0C (Table 3.2).

Various reaction conditions with p-TsOH

Equivalents of P-TsOH added % Yield of 39 1.2 30% 2.4 55% 4 55%

In summary, the highest overall yield of 55% for the reaction was achieved in boiling DMSO for the Diels-Alder reaction (24 hours) followed by dehydration/aromatization at 80 0C for 48 hours with p-TsOH (Scheme 3.4).

Scheme 3.4 Synthesis of molecular receptor 38

3.1.2 Synthesis of Receptor 33

Synthesis of clip 33 was attempted using the conditions optimized for the model reaction. Isocorannulenofuran 40, a useful synthon for the synthesis of large conjugated systems containing corannulene subunits, is used as the diene in these reactions.

Isocorannulenofuran was first synthesized in our lab in 2006 as shown in Scheme 3.5.60,61

Scheme 3.5 Synthesis of Isocorannulenofuran

Due to technical difficulties encountered with the reported preparation of 39, the

reaction conditions were reoptimized. The yield of the cycloadduct of corannulyne

(generated from bromocorannulene) and furan was 80%, but the reaction was not

reproducible.61 Therefore the synthesis of the cycloadduct 39 was attempted at various

temperatures with various equivalents of NaNH2 and t-BuOK bases (Table 3.3). An

improved yield of 95% was achieved with a full reproducibility of the reaction at slightly elevated temperature of 30-40 0C with two equivalents of t-BuOK and a large excess of

NaNH2, as shown in Scheme 3.6.

Optimization of the reaction conditions for the synthesis of 39

0 NaNH2 t-BuOK Temperature C Yield (equivalents) (equivalents) 1 2 25 (a) 2 2 25 (a) 5 2 25 (a) excess 2 25 (a) 1 2 35 (a) 2 2 35 (a) 5 2 35 (a) excess 2 35 95% *excess 2 35 50% no product formed , * - microwave reaction

Scheme 3.6 Improved synthesis of the cycloadduct 39

As previously reported, 40 was prepared by “s-tetrazine” approach by a brief heating of 39 with commercially available 2,6-bis-2-pyridyl-1,2,4,5-tetrazene.61

The synthesis of receptor C62H34O2 (33) is outlined in scheme 3.7. Two equivalents of isocorannulenofuran react with one equivalent of Klärner’s tether 35 under reflux in DMSO, producing a mixture of Diels-Alder adducts. The next step was done in the same pot by adding 2.4 equivalents of p-TsOH at 80-900C which produced hydrocarbon 33 with 45% yield.

Scheme 3.7 Synthesis of molecular receptor 33

Compound 33 was characterized by both 1H and 13C NMR (Chapter 5) spectroscopy which exhibited the expected numbers of symmetry independent hydrogen and carbon atoms, respectively, as well as by MS (Figure 3.2).

APPI MS of 33

1H NMR spectra of 33

1H NMR spectra (Figure 3.3) shows the singlet for aromatic protons ‘a’ at 8.26

ppm. The corannulene protons ‘b’ are observed at 7.78 ppm with the characteristic

corannulene coupling constants of 8.7 Hz. The other corannulene protons are observed at

the usual range of 7.4 – 7.6 ppm. In the aliphatic region of the NMR we observe the –

OCH3 protons as a singlet at 4.06 ppm and the aliphatic protons ‘c’ are seen at 4.7 ppm.

The bridge head protons are seen at 2.61 and 2.70 ppm. All these signals in the 1H NMR spectra confirm the structure of 33.

3.2 Synthesis of Molecular Receptor 34

As discussed in Chapter II, MM2 computational studies suggest the receptor 34

will be potentially the most efficient corannulene based receptor for fullerenes. Bis-

dienophile 31 ( Figure 3.4), a precursor for the synthesis of 34 (Figure 3.5), was

introduced by Klärner when synthesizing sterically rigid macrocycles by pressure-

induced repetitive Diels-Alder reactions.48 Several molecular clips and tweezers based

on the naphthalene based tether with planar aromatic pincers are reported in literature as

hosts for small aromatic guests.51,53 The syn configuration of the bis-dienophile 31

allows for the preparation of molecular clips and tweezers with syn pincers topology by

Diels-Alder cycloaddition reactions.

Structure of Klärner’s bis-dienophiles 30 and 31..

Structure of molecular receptor 33 and 34

31 possesses an extra benzene ring when compared to tether 30. Hence the

molecular receptor 34 built from 31 and two corannulene pincers is expected to have a

larger size cleft as well as additional π-π stacking interactions with the fullerene cages in

comparison to receptor 33 (Figure 3.5). According to the MM2 studies (Figure. 3.6)

C60@34 exhibits the gas phase binding energy 11.4 kcal/mol stronger than in C60@33

(see Chapter II, section 2.3.1). Furthermore, 31 possesses methoxy substituents that can be further converted to other functional groups allowing for the amalgamation of them into solid surfaces for future applications.

Space filling representation of the arrangement in C60@34 calculated by MM2

3.3 Synthesis of Molecular Receptor 34

Dienophile 31, the precursor for 34, was previously synthesized by two synthetic routes by Klärner starting from 47 or 48 (Scheme 3.8).48

Scheme 3.8 Two synthetic routes to synthesize 31

Diene 41, a necessary starting material for both routes, was first prepared

following the synthetic procedure developed by Alder et al (Scheme 3.9).62 Compound

41 was obtained in a disappointingly low overall yield of 30%.

Scheme 3.9 Synthesis of diene 41

Since the yield was not satisfactory for a large scale preparation, an alternative procedure proposed by Toda et al. was tested (Scheme 3.10).63 Originally, the synthesis of the intermediate 46 was achieved in benzene in an autoclave at 180 0C. We modified the procedure substituting benzene with toluene and performing the reaction in a pressurized vial heating the mixture to 180 0C in an oil bath. Compound 46 was purified by vacuum distillation. We obtained 46 in 60% isolated yield.

The second step of the synthesis was followed as reported by Toda el al and produced compound 41 in 75% yield. The overall yield of the reaction (45%) was significantly better as compared to the first approach (Scheme 3.10).

Scheme 3.10 Alternative synthesis of diene 41

Synthesis of the precursor 43 was reported by Klärner et al. as shown in

Scheme3.11.48 The product from the reaction of 1,4-benzoquinone and 41 is dione 42.

However in our hands the reaction produced the aromatized dione 45. The same dione 45 was prepared by Klärner by DDQ oxidation of 42. The reasons behind the formation of

45 from 41 and 1,4-benzoquinone in the absence of DDQ are not clear.

Scheme 3.11 Synthesis of 43 and 45

However, since 45 was obtained in considerable yield of 45% we attempted the

synthesis of 49 by reacting 45 with cyclopentadiene (Scheme 3.12). The reaction gave

diastereomeric products 49 and 49’ in 1:1 ratio.48 Unfortunately the isolated yield of the required 49 after separation was very low (20%). Therefore, we turned to the alternative

“route 2” of synthesizing tether 31 (Scheme 3.8).48

Scheme 3.12 Synthesis of 45 and 49

The literature reported yield for the conversion of 44 to 31 was not reproduced in

our hands. After some experimentation 31 was synthesized in 97% yield by reacting 44

with NaH and MeI in THF at 0 0C, followed by stirring the reaction mixture at room

temperature for 16 hours (Scheme 3.13). An almost quantitative yield of 97% of 31 was

obtained.

Scheme 3.13 Modified Synthesis of 31 from 44

Clip 34 was then synthesized by reacting 31 with isocorannulenofuran under the

conditions applied for the preparation of 33. Thus two equivalents of isocorannulenofuran reacted with tether 31 in boiling DMSO by double Diels-Alder

cycloaddition and the resulting cycloadducts were dehydrated/aromatized in the presence

of p-TsOH at 900C to produce clip 34 in 40% isolated yield (Scheme 3.14).57 APPI-MS

(Figure 3.7) showed m/z 860.27 which corresponded to the molecular ion of 34

(C66H36O2).

Scheme 3.14 Synthesis of the molecular receptor 34

APPI-MS of Molecular Receptor 34

1 H NMR spectrum for clip 34 in CDCl3

As expected according to the 1H NMR spectra (Figure 3.8) aromatics protons ‘a’ and ‘b’ of clip 34 are seen most downfield at 8.49 and 8.50 ppm respectively. The other

aromatic proton ‘c’ is seen as a singlet at 8.01 ppm. Corannulene protons‘d’ and ‘e’ are

seen in the range 8.05 – 8.07 ppm as a multiplet remaining corannulene protons are seen

at 7.61 – 7.77 ppm. –OMe protons are seen at 4.08 ppm. Aliphatic protons f and g are

represented at 4.67 and 4.95 ppm respectively. The four bridgehead protons are seen at

2.63 and 2.71 ppm respectively. The presence of all these signals together confirms the

structure of clip 34.

The structure of the molecular receptor 34 was also confirmed by 13C NMR

spectroscopy (Chapter 5).

In conclusion, molecular receptors 33 and 34 with two corannulene pincers on the

Klärner’s tethers were synthesized by double Diels-Alder Cycloaddition reactions followed by dehydration in moderate yields of 45% and 40%, respectively.

CHAPTER IV

BINDING STUDIES USING NMR SPECTROSCOPY

4.1 Introduction to NMR Spectroscopic Method

NMR spectroscopy is one of the most important techniques used to determine the binding of supramolecular assemblies. The principal advantage of using NMR in binding studies is that it will provide a lot of microscopic information on the host-guest complex structures. Besides the quantitative information that NMR titration can produce, the comparative shifts and changes in symmetry of the signals can often give important information about how the host and guest are interacting and provide the binding stoichiometries. This technique employs several NMR signals for the independent evaluations of association constants. In addition, NMR spectrometric methods can avoid the misinterpretation provided by minor impurities which are sometime serious in other optical spectrometric methods.64

The main physical property that we will be concerned within this method is the chemical shift (δ). In order to use chemical shift data of nuclei as a tool to determine binding constant at least one site in both the free and complex molecule must give significantly different chemical shifts. When considering the NMR spectrometric method, it can be classified to two separate categories by the differences in the exchange rates.65 When the host-guest complexation equilibrium is having an exchange rate similar to the NMR time scale the NMR peaks become broadened and/or disappear which 51

results in impossible measurement. The following two cases are suitable for the

measurement by NMR spectroscopy;65

First case is when the host-guest complexation equilibrium has a very slow

exchange rate compared to the NMR timescale. In this case we can observe two separate

signals for the peaks assigned to the host part of the complex and those to the free host.65

Second case is when the host-guest complexation equilibrium has a very fast

exchange rate compared to the NMR time scale. In this situation the peaks assigned to

the host of the complex and those to the free host are fused. This fused signal appears at the weight-averaged chemical shift of the free host and the complex. In the simple 1:1 association system this chemical shift can be described by equation 4.1.66

[퐻퐺] 훥훿 = 훿훥퐻퐺 [ ⁄ ] (4.1) [퐻]0

Where,

∆훿 훿 − 훿ℎ

훿 Observed NMR chemical shift

훿∆퐻퐺 훿퐻퐺 − 훿ℎ

훿퐻퐺 NMR resonance of the complex

훿ℎ NMR resonance of the free host

[퐻퐺] Concentration of the complex

[퐻]0 Total concentration of the host

It is considered that with the modern NMR instruments it is possible to obtain

-4 -5 6 -1 good quality spectra with 10 – 10 M concentrations and Ka up to 10 M . Hence the

true limiting factor in NMR titrations is whether the system in question is in the fast or slow exchange region under the respective conditions.

It is important to note that the systems (Clip 33 and 34 with fullerenes) that we are

dealing with are having faster host-guest complexation equilibria compared to the NMR

time scale (See section 4.3 and 4.4). Hence the equations (4.1, 4.2 and 4.3)66 can be

applied to our host-guest complexation processes.

The quantitative expressions for the expected changes in the chemical shifts of the protons of the host (Δδ) assuming a 1:2 and 2:1 complexation are given in equation 4.2

and 4.3 respectively.66 1:2 equilibria results when two guests bound to a host and 2:1

equilibria results when two hosts bound to one guest. These equations will be analyzed

in more detail in the latter sections.

2 훿∆퐻퐺퐾1[퐺]+훿∆퐻퐺2퐾1퐾2[퐺] ∆훿 = 2 (4.2) 1+퐾1[퐺]+퐾1퐾2[퐺]

2 훿∆퐻퐺[퐺]0퐾1[퐻] +2훿∆퐻2퐺[퐺]0퐾1퐾2 [퐻] ∆훿 = 2 (4.3) [퐻]0(1 + 퐾1[퐻]+퐾1퐾2[퐻] )

A key factor that needs to be considered in 2:1 and 1:2 binding is the relationship

between the stepwise (microscopic) binding constants K1 and K2. It is determined that in

non-cooperative binding the stepwise binding constants K1 and K2 are related to the

equation 4.4.67

퐾1 = 4퐾2 (4.4)

This equation is a special case of a more generalized equation strictly defining the expected relationship between microscopic binding constants in any non-cooperative system where the second association is not affected by the first association of the clip to

the guest molecule. This will not be true for all the systems, in which we have observed

37 negative cooperativity for buckycatcher II, 29 (Chapter 1) with C60, where K1≫ 4K2.

When K1≫ 4K2 those systems show negative cooperativity in which the formation of 1:1 complex disfavor the 2:1 complex formation. On the other hand when 4K2 ≫ K1 those

systems are considered to have positive cooperativity where the formation of a 2:1

complex is favorable over the formation of 1:1 complex.

4.2 Evaluation of the Binding Stoichiometry

The determination of the binding constant can be done by the construction of a

plausible binding model. There are two commonly used methods to determine the

binding stoichiometry and they are the method of continuous variation (also called Job’s

plot) and the mole ratio method.64 In the method of continuous variation a series of

solutions are prepared where the total [H]0 and [G]0 molar concentrations is kept constant while [H]0/[G]0 varies in small steps by mixing different volumes of the two components

such that total volume kept constant. In molar ratio method the total host concentration

64 [H]0 is kept constant while the total guest concentration [G]0 is varied. We have used

the modified Job’s plot method to determine the binding stoichiometry of the inclusion

complex formation.65 In the modified Job’s plot method the stoichiometry is determined

from the x coordinate at the maximum in the curve where (mole fraction × Δδ) is plotted

as the y coordinate (Figure 4.4 and Chapter 5).

In NMR titration a series of measurements are done by changing the relative

concentration of the components. These changes should happen stepwise to infer the

nature and type of complexation. If anything other than 1:1 stoichiometry is assumed it is

beneficial to fit the data to other plausible models such as 1:2 and 2:1 and check the quality of each fit.

4.3 Fullerene Binding Studies with Clip 33

Illustration of the NMR titration

The complexation of 33 with fullerenes take place in solution as evidenced by

changes in the chemical shifts of the protons in 33 upon successive addition of C60 and

C70. The NMR titration experiments in toluene-d8 (Figure 4.2 & 4.5) show downfield

shifts for the protons in the corannulene subunits with increasing concentrations of C60 or

C70. Maximum changes in the chemical shifts of protons A and B (Figure 4.3) upon

addition of C60 are 0.26 and 0.19 ppm, respectively (Table 4.1). Maximum changes in

the chemical shifts of the same protons upon addition of C70 are 0.15 and 0.21 ppm,

respectively (Table 4.1). The binding stoichiometries for the inclusion complexes for

both C60 and C70 were determined to be 1:1 according to a Job’s plot analysis (Figure 4.4

and 4.6).

Changes in the chemical shifts of the protons A and B observed in 33 upon addition of C60 and C70

Proton/S A B

Δδ (C60@33) 0.13 0.26 ppm

Δδ (C70@33) 0.15 0.21 ppm

1 H NMR titration of 600 μL of clip 33 solution with 20 to 1500 μL of C60 solution in toluene-d8

1 H NMR titration of 600 μL of clip 33 solution with 20 to 1500 μL of C60 solution in toluene-d8 (aromatic region)

Job’s plot for proton A in 33 upon complexation with C60

1 H NMR titration of 600 μL of clip 33 solution with 20 to 1500 μL of C70 solution in toluene-d8

Job’s plot for proton A in 33 upon complexation with C70

4.3.1 Estimation of the Binding Constants of 33 with Fullerene in Toluene-d8

Since the Job’s plot method confirmed that clip 33 forms inclusion complexes

with C60 and C70 in 1:1 stoichiometric ratio, Ka was evaluated from the changes in chemical shifts by applying a nonlinear curve-fitting equation shown in 4.5.68 This was

derived using equations 4.6 and 4.7 by considering the 1:1 inclusion complex

formation.68

1⁄ 퐿(1+퐾 × [퐺] +퐾 ×[퐻] )−(퐿2×(1+퐾 ×[퐺] +퐾 ×[퐻] )2−4퐾2[퐺] [퐻] 퐿2) 2 ∆훿 = 푎 0 푎 0 푎 0 푎 0 푎 0 0 (4.5) 2퐾푎[퐻]0

where

[G]0 Total concentration of the guest

[H]0 Total concentration of the host

L Δmax ; that is Δ at 100% complexation

[퐻퐺] 퐾 = (4.6) 푎 [퐺] [푯]

훿퐻 = 푥훿푐 + (1 − 푥 )훿ℎ (4.7)

푥 is the mole fraction of the inclusion complex, i.e.

푥 = [HG] / [H]0

δH observed chemical shift of a specific nucleus in clip 33

δh chemical shifts of a specific nucleus in clip 33 in the free form

δc chemical shifts of a specific nucleus in clip 33 when bound to the guest

Ka and L (fig 4.4) were optimized as parameters in the non-linear curve fitting

using Origin© (v. 8.0).

Nonlinear curve regression of the titration of 33 with C60

Nonlinear curve regression of the titration of 33 with C70

-1 The estimated Ka values were 2400±30 and 2700±80 M for protons A and B

-1 respectively, in the C60 NMR titration experiment and 2670±106 and 3220±120 M for protons A and B in the C70 NMR titration experiment. The average Kassoc values were

-1 -1 therefore 2550 ± 85 M for C60@33 and 2950 ± 160 M for C70@33. These association

constants are larger than what we expected from MM2 studies and are similar to the

previously reported buckycatcher 2033 and to the bi- and tridental corannulene-based

receptors reported to date (except for buckycatcher 29).34,36

4.4 Fullerene Binding Studies with Clip 34

4.4.1 Binding Studies of Clip 34 with C60

1 At first H NMR titrations were carried out in toluene-d8 (Figure 4.9) In contrast

to clip 33, association of 34 with C60 goes beyond the usual 1:1 inclusion complex

formation as indicated by the continuous variation plot. Attempts to estimate the

microscopic association constants K1 and K2 for receptor 34 with C60 by NMR titrations

in deuterated toluene failed, presumably owing to the limited solubility of the

supramolecular complexes and to the very high association constants in this solvent.

1 H NMR titration of 600 μL of clip 34 solution with 10 to 1500 μL of C60 solution in toluene-d8

In order to minimize the potential errors, 1H NMR titrations were carried out in chlorobenzene-d5. Changes in NMR chemical shifts of 34 were observed upon addition of C60 which suggested that clip 34 form inclusion complexes with C60. Corannulene protons (7.4 – 8.0 ppm, Figure 4.12) and methoxy protons (signal 4.0 ppm in the aliphatic region, Figure 4.12) in 34 showed downfield shifts upon successive addition of C60. All the other aliphatic protons (signals 4.6 & 4.9 ppm Figure 4.12) and aromatic (1, 2 & 3 signals in Figure 4.12) showed upfield shifts upon binding with C60. According to Job’s plot analysis binding stoichiometry in this case also goes beyond the 1:1 model and was assumed to be 2:1(figure 4.10).

Job’s plot for proton 3 in 34 upon titration with C60

1H NMR spectrum of the symmetry independent aromatic protons of 34 in chlorobenzene-d5

Changes in the chemical shift of protons in clip 34 upon successive addition of C60 in chlorobenzene-d5

4.4.2 Binding Studies of Clip 34 with C70

Clip 34 also showed NMR chemical shift changes upon addition of C70 in chlorobenzene-d5. Aromatic proton 3 in Clip 34 showed a higher chemical shift change

with C60 than with C70. Contrarily, –OCH3 protons in 34 showed a more pronounced

change in the chemical shift upon binding with C70 than with C60. Methoxy protons, the

proton at 4.9 ppm in the aliphatic region and the corannulene protons 4 and 5 showed

down-field shifts upon addition of C70. All the other corannulene protons 7.4-7.7 ppm,

aromatic protons 1-3 and aliphatic proton at 4.6 ppm in clip 34 showed up-field shifts

upon binding with C70 (Figure 4.14). Job’s plot method showed that 34 and C70 form a

2:1 inclusion complex formation (Figure. 4.13). The maximum chemical shift changes of the protons in clip 34 observed upon binding with C60 and C70 are shown in Table 4.2.

Job’s plot for proton 5 (at 7.90 ppm, Figure 4.11 and Table 5.5) in 34 upon titration with C70

Changes in the chemical shifts of protons in clip 34 upon successive addition of C70 in chlorobenzene-d5

Maximum observed changes in the chemical shifts of selected protons in 34 upon addition of C60 and C70

Proton 8.23 ppm 7.93 ppm 7.89 ppm 4.6 ppm 3.96 ppm

Δδ (C60@34) -0.156 0.095 0.1 -0.092 0.086

Δδ (C70@34) -0.033 0.011 0.037 -0.039 0.213

4.4.3 Binding Studies of Clip 34 with PCBM

The titration of clip 34 by 1-3(-(methoxycarbonyl)propyl)-1-phenyl[6,6]C6169

(PCBM) (Figure 4.15, 50) in chlorobenzene-d5 was also studied. We have used the

derivative of fullerene PCBM instead of pristine fullerene in order to reduce the ability of

the clips to form 2:1 assemblies. Chemical shift changes of protons in 34 observed upon

successive addition of 50, suggest that there is an inclusion complex formation between

PCBM and 34. Although we expected only the dimeric aggregation (PCBM@34),

continuous variation plot (Figure 4.16) based on the titration in chlorobenzene showed

the binding stoichiometry goes beyond the usual 1:1 inclusion complex formation.

The structure of PCBM (50)

Job’s plot for proton at 3.9 ppm in 34 with PCBM

Changes in the chemical shifts of protons in clip 34 upon successive addition of PCBM in chlorobenzene-d5. 600 μL of clip 34 solution with 10-1500 μL of PCBM solution.

4.4.4 Estimations of the Binding Constants of 34 with Fullerenes in Chlorobenzene-d5

In contrast to 33, association of 34 with C60 and C70 goes beyond the usual 1:1

inclusion complex formation as indicated by the continuous variation plots based on the

titration in both toluene-d8 and chlorobenzene-d5. By analogy with buckycatcher II (29)

we assume that the trimeric aggregates C60@342 and C70@342 are formed in addition to

the 1:1 supramolecular assemblies, as described by equation (4.8). If anything other than

1:1 stoichiometry is assumed it is beneficial to fit the data to other plausible models such

as 1:2 and 2:1 and check the quality of each fit. The best fits of the titration data obtained

for clip 34 association with C60, C70 and PCBM were obtained by using the 2:1 binding

model (4.8) and binding equation (4.9).

K1 K2 Clip 34 C C @34 Clip 34 C @34 70/60 70/60 70/60 2 (4.8)

2 훿∆퐻퐺[퐺]0퐾1[퐻] +2훿∆퐻2퐺[퐺]0퐾1퐾2 [퐻] ∆훿 = 2 (4.9) [퐻]0(1 + 퐾1[퐻]+퐾1퐾2[퐻] )

Parameters and Variables:

∆훿 훿 − 훿0

퐾1 The first stepwise association constant

퐾2 The second stepwise association constant

훿∆퐻퐺 훿퐻퐺 − 훿ℎ

훿∆퐻2퐺 훿퐻2퐺 − 2훿ℎ

[퐺]0 The total concentration of the guest

[퐻]0 The total concentration of the host

[퐻] Molar concentration of the free host

훿0 Chemical shift of a given proton in free host

훿 Observed chemical shift of the same proton

훿퐻퐺 Chemical shift of the same proton in 1:1 complex

훿퐻2퐺 Chemical shift of the same proton in 2:1 complex

For a given set of K1, K2, [G]0 and [H]0 the concentration of free host [H] was

calculated by solving the following cubic equation:66

퐴[퐻]3 + 퐵[퐻]2 + 퐶[퐻] + 퐷 = 0 (4.10)

Where;

A = (K1K2)

B = K1 (2K2[G]0 - K2[H]0 + 1)

C = K1 ([G]0 - [H]0) + 1

D = -[H]0

[H]0 = [H] + [HG] + 2[H2G]

Using the calculated [H] for each titration the expected Δδ was calculated by the

equation 4.9. K1, K2, δΔHG and δΔH2G were optimized as parameters in the non-linear

curve fitting using Origin© (v. 8.0).

Our efforts to evaluate the microscopic association constants K1 and K2 for the

C60@34 and C60@342 in toluene-d8 were unsuccessful, possibly due to the limited

solubility of the C60@34 complexes and to the very high association constants. From

previously reported studies for the receptors 23 and 29 in various solvents, the association

constants of such receptors with fullerenes in chlorobenzene are lowered by ca. one order

of magnitude as compared to toluene solvent.37,47 Moreover, chlorobenzene is a better

solvent for both the host and guest molecules as well as for their supramolecular

complexes. However, even in chlorobenzene-d5 we were able to obtain only a very crude

4 3 -1 estimation of the association constants of 34 with C60 (ca. 5×10 and 8×10 M for K1 and K2, respectively). Moreover, even for PCBM only a crude estimation for the 69

4 3 association constant was obtained (ca. 1 × 10 and 4 × 10 for K1 and K2, respectively, in

chlorobenzene-d5). In contrary, a better quality fitting of the NMR titration data of 34

with C70 in the same solvent allowed for a more reliable estimation of K1 and K2.

Significant dilution of the host during the titration experiment could be a source of large errors if a dimerization of the host competes with the inclusion complex formation. However, in the absence of C60 or C70 we did not observe any measurable changes in the 1H NMR chemical shifts of 34 upon dilution in the concentration ranges

studied in chlorobenzene. We therefore concluded that the host dimerization is negligible

in the titration experiment.

Four different protons in clip 34 which showed significant change in the chemical

shift upon complexation with C70 were taken in to consideration when determining K1 and K2. All the nonlinear curve regressions for the titration of 34 with C70 are included in

chapter 5.

Nonlinear curve regression of the titration of 34 with C70

5 5 The calculated K1 values were (2.3 ± 0.8) × 10 , (2.3 ± 0.6) × 10 , (2.0 ± 0.6) ×

5 5 -1 4 4 10 and (1.5 ± 0.7) ×10 M and K2 values were (4.0 ± 1) ×10 , (3.0 ± 0.7) ×10 , (2.5

± 0.7) ×104 and (4.0 ± 0.002) ×104 M-1 for protons 9, 10, 5 and 11, respectively, in the

C70 NMR titration experiment. While the maximum chemical shift changes were

observed for methoxy protons, due to broadening of the peak it was not taken into

consideration when determining the binding constants. The average K1 and K2 values

5 -1 4 -1 57 were therefore (2.0 ± 0.7) ×10 M and (3.0 ± 0.7) ×10 M for C70@34. The

association constant (K1) observed in this solvent is two orders of magnitude higher than

47 in C70@23 (Table 4.3) . The Gibbs free energy of 1:1 complexation of C70 with 34 is

therefore ca. 3 kcal/mol more exergonic than with 23. Gas phase binding energies for the

two buckycatchers in 1:1 complexes differ by 5.5 kcal/mol (according to MM2 studies) in

favor of 34. The solvation and entropy penalties associated with formation of the

inclusion complexes are considered to be comparable in both cases hence the difference

in the binding affinities of the two molecular receptors is largely caused by the stronger

binding of C70 by 34. We therefore conclude that the improved binding affinity toward

C70 shown by 34 with respect to 23 results from the stronger attractive dispersion

interactions of C70 with the pincers forming the perfect cavity size and some contribution from the naphthalene spacer.

The determined K1/K2 ratio for C70@34 is 6.6, significantly higher than 4. As

previously discussed this indicates a negative cooperativity, which means that 1:1

complexation is favored over the formation of a 2:1 complex. The overall affinity of 44

9 -2 towards C70, defined as K1 × K2, is ca. 6 x 10 M , by far surpassing the performance of

all previously reported molecular clips with corannulene pincers.33,35,36

Comparison of the binding properties of buckycatchers 23, 29 and 34 in chlorobenzene

K1 K2 47 2 C60@23 (5 ± 0.2) × 10 a 47 2 C70@23 (9 ± 0.9) × 10 a 37 4 3 C60@29 (1 ± 0.1) × 10 (1 ± 0.6) × 10 4 b 3 b C60@34 (5 × 10 ) (8 × 10 ) 57 5 4 C70@34 (2 ± 0.7) × 10 (3 ± 0.7) × 10 a – no K2 observed, b – crude estimation

4.5 Crystal Structure Determination for the Inclusion Complex Formation

Crystal growth for the inclusion complex formation between clip 34 and C60 was

attempted in various solvents. Both clip 34 and C60 were separately dissolved in toluene,

CS2, dichlorobenzene and chlorobenzene. Small portions of C60 and clip 34 dissolved in

same solvent were mixed and allowed for slow evaporation. Mixed solvent combinations

(DCM/toluene, toluene/dichlorobenzene) were also tested. The X-ray quality crystals

were observed by slow evaporation of mixed solutions of C60 and 34 in o-

dichlorobenzene. The X-ray crystal structure for C60@Clip 34 (1:1 inclusion complex

formation) is shown in Figure 4.19.

Crystal arrangement in C60@34 (left) and Crystal packing pattern seen along a crystallographic axis (right).

Disordered solvent contributions are removed for clarity.

The high affinity of clip 34 for fullerenes can be explained by a closer look at the crystal structure of C60@34 in which the fullerene molecule is placed in the center of the

doubly concave receptor with most of the corannulene carbon atoms being in van der

Waals contact with the carbon atoms in fullerene. In the solid state the C60 guest is

ordered, and it makes 23 C…C contacts of less than 3.4 Å to the host (3.154(4) –

3.384(4) Å), one of which is to one of the carbon atoms of the naphthalene part of the

tether. Although each C60 cage is wrapped by 34 and the included solvent molecules, it still is in close contacts with three neighboring carbon cages showing 10 intermolecular

C…C contacts with other C60 molecules in the range 3.264(4) – 3.399(4) Å. The nearest

centroid-centroid distances between these C60 molecules are 9.802, 9.876 and 10.101 Å,

very close to the distance indicating van deer Waals contacts of the cages.

Inclusion complex formation for clip 34 with C60 and C70 was observed by

atmospheric pressure photoionization mass spectrometry (APPI-MS). 1:1 inclusion

complex formation of C60@34 (Figure 4.20) and C70@34 (Figure 4.21) was detected at

m/z 1580.3 and 1700.3 respectively. Even with several attempts we did not observe the

2:1 inclusion complex formation by mass spectrometry. This can be due to several

reasons. Since clip 34 prefers the first complexation over the second (as we observed

from the K1/K2 ratio) the amount of the trimer present in solution is quite low, especially

in the very dilute samples required for the MS injections. Another possible explanation

is that even though the 2:1 complex is forming it might not be ionizing well to be

detected by MS.

APPI-MS of C60@clip 34 1:1 inclusion complex formation

The upper and lower traces show the experimental and stimulated spectra.

APPI-MS of C70@clip 34 1:1 inclusion complex formation

The upper and lower traces show the experimental and stimulated spectra.

In summary clip 33 showed notable binding constants with both C60 and C70 in

deuterated toluene. While significant, these association constants are very similar to 23

and to the other bi and tridental corannulene based receptors reported up to date. On the

other hand, 34 showed a remarkable affinity (two orders of magnitude higher) for

fullerenes compared to 33 and to all the other corannulene based receptors synthesized up

to date. MM2 calculations find 33b with concave-convex π-π stacking of the

corannulene pincers to be the lowest energy conformer for 33 that suffers from the more

severe host deformation penalty than 34d (the lowest energy conformer of 34, Chapter 2).

Hence the inclusion of the fullerenes in 33 required a significant change in the structure

from closed conformer to open conformer. The calculated deformation penalty in

C60@33 is ca.7.2 kcal/mol higher than in C60@34, accounting fully for the difference in

the experimental binding energies of the two complexes.

Even in deuterated chlorobenzene the titrations of clip 34 with C60 provide only a

crude estimation of the association constants (Table 4.3), presumably owing to the

limited solubility of the inclusion complexes in this solvent. Notwithstanding the limited 75

accuracy, the association constants observed in this solvent is two order of magnitude higher than for C60@23 and one order higher than the association of C60@29. A

significantly higher affinity of 34 for C70 compared to C60 shown by the NMR titrations

can be explained by the molecular modeling study that was presented in Chapter 2. The

gas phase binding energy calculated for C70@34 inclusion complex is 1.2 kcal/mol higher than that of C60@34. Assuming that both the solvation and entropy penalties associated

with the supramolecular complex formation are comparable in both cases, we can

conclude that the stronger dispersion based attractions of C70 by 34 results in the stronger

complex formation over C60@34.

Very high Ka values of 34 with fullerenes as compared to that of clip 33 and to all

the other corannulene based receptors, suggested that 34 forms a perfect size cleft for

fullerene. X-ray crystal structure determination of C60@34 along with MM2 studies

provides a rationale for the efficiency of this receptor in the size/shape recognition of

fullerenes. The longer naphthalene spacer in 34 not only pre-organizes the corannulene

pincers into a favorable topology but, in addition, it contributes to some extent to the

attractive dispersion interactions with the guest fullerene cages. Also, 34 exhibits some

preference in binding C70 over C60 owing to the stronger gas phase binding energies of the former carbon cage with the receptor.

4.6 Potential Applications of Molecular Receptors

The binding affinities of clip 33 and 34 toward fullerenes could make them

attractive candidates for novel materials, including photovoltaic devices. Fullerenes and

their derivatives are frequently used as electron acceptors in polymer based solar cells.70

A significant factor in the supramolecular assemblies 33 and 34 with fullerenes is the 76

shape complementarity of the concave surface of the receptor with the convex surface of fullerene. It has been recently shown that molecular shape complementarity between donors and acceptors in organic polymer solar cell devices give rise to the higher efficiency of power conversion.71

When considering the possible use of our molecular clips in material sciences, it is important to immobilize them on solid supports such as gold nanoparticles or silica, and study their charge transfer response. In order to incorporate these molecular receptors on to solid supports, polar groups needed to be introduced to the host. Hence the presence of methoxy groups in molecular clip 33 and 34 will be useful as they can be

converted to other functional groups such as hydroxy or acetates and these in turn will

allow for the attachment of the clips to required solid supports. Future studies will look

at the possibility of attaching 34 to solid supports and investigate the possible formation

of molecular bilayers formed by the receptors and fullerenes.

We believe that the design of specific receptors for selected guest molecules, as

described in this study, will contribute to the novel areas of supramolecular chemistry

with potential applications in nanotechnology as well as in material sciences.

CHAPTER V

EXPERIMENTAL SECTION

Reaction solvents were purified using an Innovative Technology solvent purification system or by distillation. All chemicals used for the reactions were purchased from Sigma-Aldrich or Alfa-Aesar. All reactions were done under either nitrogen or argon atmosphere. Column chromatography was carried out on silica gel

Silicycle 230-400 mesh. 1H NMR and 13C NMR spectra were recorded on 600 and 300

MHz spectrometers from Bruker (Avance III). All chemical shifts were reported in ppm

using the following deuterated solvents; toluene-d8, chloroform-d, and chlorobenzene-d5.

Splitting patterns were classified as follows; singlet (s), doublet (d), triplet (t), quartet (q),

doublet of doublet (dd) and multiplet (m). The coupling constants are reported in Hertz

(Hz). APPI and ESI mass spectra were recorded on MicroTOF-QII (Bruker).

5.1 Synthesis of 38

65 mg (0.3 mmol) of phenanthrenefuran 36 and 18 mg (0.07mmol) of 30 in 5ml of anhydrous DMSO was refluxed for 24 hours. 34 mg (0.18 mmol) of p-TsOH was then added and the mixture was stirred at 800C for 24 hours. The reaction was cooled to rt and diluted with water. The crude mixture was extracted with dichloromethane. The dark brown solution was dried over anhydrous MgSO4, filtered and concentrated in vacuo.

The remaining dark solid was purified by column chromatography on silica gel

(DCM:cyclohexane 3:1) yielding 23mg (52%) of 38.

1 H NMR (600 MHz, CDCl3): δ 2.57 (2H, d, J = 7.6 Hz), 2.64 (2H, d, J = 7.6 Hz,),

3.95(6H, s), 4.68 (4H, s), 7.46-7.51 (8H, m), 8.41 (4H, s), 8.45-8.47 (8H, t);

13 C NMR (600 MHz, CDCl3): δ 48.3, 61.7, 65.7, 116.0, 123.1, 123.2, 126.5,

126.9, 127.5, 129.5, 130.1, 140.1, 149.3.;

APPI-MS: C50H34O2 : calcd. 666.26, found 666.26.

1H NMR spectrum of 38

13C NMR spectrum of 38 80

APPI-MS of 38

5.2 Synthesis of 33

130 mg (0.4 mmol) of isocorannulenofuran 40 and 30 mg (0.1 mmol) of dienophile 30 in 5ml of anhydrous DMSO was refluxed for 48 hours. 51 mg (0.3 mmol) of p-TsOH was then added and the reaction mixture was stirred at 80 ºC for 48 hours.

After cooling the reaction mixture was diluted with water and extracted with dichloromethane. The dark brown solution was washed with water, dried over MgSO4, filtered and the solvents were removed in vacuo. The remaining dark solid was purified by column chromatography on silica gel (DCM:cyclohexane 3:1) yielding 41mg (45%).

1 H NMR (600 MHz, CDCl3) δ: 2.61 (2H, d, J = 7.9 Hz), 2.70 (2H, d, J = 7.9 Hz),

4.06 (6H, s), 4.72 (4H, s), 7.47 (7H, s), 7.52 (5H, d, J = 8.7 Hz), 7.78 (4H, d, J = 8.7 Hz),

8.26 (4H, s).

13 C DEPT-Q135 (150 MHz, CDCl3) δ: 48.40, 61.82, 65.51, 117.81, 123.76,

126.32, 126.61, 126.80, 128.59, 129.53, 130.10, 130.62, 133.42, 134.70, 136.54, 140.55,

146.00, 149.44

APPI MS: C62H34O2: calcd. 810.2, found 810.2

APPI-MS of 33

1H NMR spectrum of 33 82

13C DEPT-Q135 NMR spectrum of clip 33

5.3 Synthesis of Dione 45

Diene 41 (0.5 g, 4 mmol) was added to a degassed solution of p-benzoquinone 47

(0.6 g, 5.5 mmol) in anhydrous toluene under nitrogen. The mixture was stirred at 60 0C

for 11 days. After cooling to room temperature the reaction mixture was concentrated in

vacuo. The remaining dark solid was dissolved in DCM and purified by column

chromatography on silica gel (Chloroform) leads to 0.42 g (45%) of dione 45.

1 H NMR (600 MHz, CDCl3):  = 2.27 (1H, d, 7.5 Hz), 2.42(1H, d, 7.5Hz,),

4.04(2H, s), 6.79(2H, s), 6.87(2H, s), 7.87(2H, s);

13 C NMR (600 MHz, CDCl3): δ = 50.68, 69.65, 118.76, 130.12, 138.33, 142.68,

159.02, 185.79.;

ESI MS: calcd.[M+Na] C15H10O2: 245.05, found. [M+Na] 245.05.

1H NMR spectrum of dione 45

13C NMR spectrum dione 45

ESI MS of dione 45

5.4 Synthesis of 31

A solution of compound 44 (850 mg, 3 mmol) in 6 ml of anh. THF was added dropwise to a slurry of sodium hydride (0.82 g of a 60% oil dispersion, 20 mmol) in 2 mL of anh. THF. After the addition was complete, the reaction mixture was cooled to 0 ºC and 3.0 ml (6.8 g, 48 mmol) of MeI was added dropwise. The flask was allowed to warm up to room temperature and the reaction mixture was stirred for 16 hours. Diethyl ether and water were added and separated. The aqueous phase was extracted three times with ether. The combined organic layers were washed with water, dried, and the solvents were evaporated under reduced pressure. The crude product was purified by column chromatography (cyclohexane: ethylacetate 10:1) to give 0.91 g (97%) of 31 as a white

solid.

1 H NMR (600 MHz, CDCl3): δ = 2.17( 1H, d, J = 7.3 Hz), 2.23 ( 1H, d, J = 7.5

Hz), 2.26 ( 1H, d, J = 7.5 Hz), 2.35 (1H, d, 7.3 Hz), 3.93 (6H, s), 3.97 (2H, s), 4.27 (2H,

s), 6.72 ( 2H,s), 6.74 (2H,s), 7.80 (2H, s);

13 C DEPTQ135 (150 MHz, CDCl3): δ = 46.96, 49.94, 62.20, 65.72, 67.32,

114.07, 125.65, 136.16, 141.98, 142.36, 145.92, 148.64;

ESI MS: C22H20O2 calcd. 316.14, found 316.14

1H NMR spectrum for 31

13C NMR spectrum for compound 31

ESI MS of 35

5.5 Synthesis of Molecular Receptor 34

160 mg (0.6 mmol) of isocorannulenofuran 40 and 35 mg (0.1 mmol) of dienophile 31 were refluxed in 3 mL of anh. DMSO for 48 hours. 83 mg (0.4 mmol) of p-TsOH was then added and the reaction mixture was stirred at 80-90 ºC for another 48 hours. The reaction was cooled to rt and diluted with water. The crude mixture was extracted with dichloromethane. The dark brown solution was dried over MgSO4, filtered and concentrated in vacuo. The remaining dark solid was purified by column chromatography on silica gel (DCM: Cyclohexane 3:1) giving 37 mg (40%) of 34.

1 H NMR (600 MHz, CDCl3)  : 2.63 ( bs, 2H ), 2.71 (m, 2H), 4.08 (s, 6H), 4.67

(s, 2H), 4.95 ( s, 2H), 7.61-7.70 (m, 8H), 7.73- 7.77 (m, 4H), 8.01 (s, 2H), 8.05-8.07 (m,

4H), 8.49 (s, 2H), 8.50 (s, 2H);

13 C DEPT-Q135 (150 MHz, CDCl3, ppm):  = 48.2, 51.3, 62.3, 63.6, 64.9, 114.6,

117.8, 117.9, 124.0, 126.5, 126.61, 126.63, 126.8, 126.9, 127.0, 127.1, 128.92, 128.95,

129.8, 129.9, 130.4, 130.5, 131.0, 131.1, 133.8, 134.0, 135.01, 135.08, 135.33, 135.33,

136.9, 137.0, 145.9, 147.3, 148.5, 148.9.;

APPI MS: C66H36O2: calcd. 860.27, found 860.27

1H NMR spectrum of clip 34

13 C DEPTQ135 NMR of 34 (150 MHz, CDCl3)

APPI-MS of clip 34

5.6 Synthesis of Starting Materials

Synthetic outline for dienophile 30

Synthesis of dienophile 30 was successfully achieved following the procedure

developed by Klärner et al.48

Synthetic outline for dienophile 31

Synthesis of dienophile 31 was successfully achieved by Route 2. Starting

materials 48, 43 and 44 were synthesized using the procedure developed by Klärner et

al.48 Compound 41 was synthesized according to the procedure developed by Toda et al63 with few modifications as described in Chapter III.

5.7 1H NMR Titration Experiments for clip 33

5.7.1 Titration of 33 with C60 in toluene-d8

A stock solution of 33 was prepared by dissolving 1.51mg of the clip 33 in 5mL

-4 of toluene-d8 (3.72×10 M). 600µL aliquot of the above solution was subsequently

titrated with 20, 40, 60, 80, 100, 130, 170, 230, 300, 400, 500 and 1500 µL of 2.2×10-3M

1 solution of C60 in toluene-d8 and H NMR spectra were recorded after each addition.

Association constant Ka was estimated from the changes in chemical shifts using the non-

linear curve fitting tool in Origin 8.0 (Chapter 4 and Table 5.1).

1 H NMR titration data for C60@33 in toluene-d8

C60 added (μL) [33] M [C60] M

0 0.000373 0.000000

20 0.000361 0.000071

40 0.000350 0.000138

60 0.000339 0.000200

80 0.000329 0.000259

100 0.000320 0.000314

130 0.000306 0.000392

170 0.000291 0.000486

230 0.000270 0.000610

300 0.000249 0.000734

400 0.000224 0.000880

500 0.000203 0.001000

1500 0.000107 0.001572

Table 5.1 (Continued)

Proton a (8.18 ppm) ∆δ of a Proton b (7.5 ppm) Δδ of b

8.1766 0.0000 7.5447 0.0000

8.1908 0.0142 7.5737 0.0290

8.2045 0.0279 7.5985 0.0538

8.2162 0.0396 7.6223 0.0776

8.2257 0.0491 7.6399 0.0952

8.2342 0.0576 7.6554 0.1107

8.2451 0.0685 7.6760 0.1313

8.2556 0.0790 7.6947 0.1500

8.2676 0.0910 7.7164 0.1717

8.2776 0.1010 7.7350 0.1903

8.2867 0.1101 7.7526 0.2079

8.2930 0.1164 7.7598 0.2151

8.3115 0.1349 7.7970 0.2523

Table 5.1 (Continued)

Mole fraction (MR) MR x Δδ of a MR x Δδ of b

1.0000 0.0000 0.0000

0.8356 0.0119 0.0242

0.7176 0.0200 0.0386

0.6288 0.0249 0.0488

0.5596 0.0275 0.0533

0.5041 0.0290 0.0558

0.4388 0.0301 0.0576

0.3742 0.0296 0.0561

0.3065 0.0279 0.0526

0.2531 0.0256 0.0482

0.2026 0.0223 0.0421

0.1689 0.0197 0.0363

0.0635 0.0086 0.0160

5.7.1.1 Job’s plot for clip 33 with C60

Jobs plot for protons A(left) and proton B (right) for the titration of 33 with C60

Nonlinear curve regression of the titration of 33 with C60

5.7.2 Titration of 33 with C70 in toluene-d8

-4 0.28 mg of 33 was dissolved in 1 mL of toluene-d8 to give 3.53×10 M stock

solution. 600 µL of the solution was titrated with 20, 40, 60, 80, 100, 130, 180, 230, 300,

-3 1 400, 500 and 1500 µL of 2.53×10 M solution of C70 in toluene-d8 and H NMR spectra

were recorded after each addition (Table 5.2).

1 H NMR titration data for C70@33 in toluene-d8

C70 added (μL) [33] M [C70] M

0 0.000353 0.000000

20 0.000342 0.000082

40 0.000331 0.000158

60 0.000321 0.000230

80 0.000311 0.000298

100 0.000303 0.000362

130 0.000290 0.000451

170 0.000272 0.000585

230 0.000255 0.000702

300 0.000235 0.000844

400 0.000212 0.001013

500 0.000193 0.001152

1500 0.000101 0.001810

Table 5.2 (Continued)

Proton a (8.18 ppm) ∆δ of a Proton b (7.5 ppm) ∆δ of b

8.1817 0.0000 7.5632 0.0000

8.2026 0.0209 7.5950 0.0318

8.2188 0.0371 7.6167 0.0535

8.2329 0.0512 7.6399 0.0767

8.2448 0.0631 7.6558 0.0926

8.2531 0.0714 7.6689 0.1057

8.2650 0.0833 7.6869 0.1237

8.2789 0.0972 7.7068 0.1436

8.2879 0.1062 7.7204 0.1572

8.2974 0.1157 7.7309 0.1677

8.3074 0.1257 7.7435 0.1803

8.3132 0.1315 7.7508 0.1876

8.3324 0.1507 7.7760 0.2128

Table 5.2 (Continued)

Mole fraction (MR) MR x ∆δ of a MR x ∆δ of b

1.0000 0.0000 0.0000

0.8070 0.0169 0.0257

0.6764 0.0251 0.0362

0.5822 0.0298 0.0447

0.5110 0.0322 0.0473

0.4553 0.0325 0.0481

0.3914 0.0326 0.0484

0.3172 0.0308 0.0455

0.2666 0.0283 0.0419

0.2179 0.0252 0.0365

0.1729 0.0217 0.0312

0.1433 0.0188 0.0269

0.0528 0.0080 0.0112

5.7.2.1 Job’s plot for clip 33 with C70

Job’s plot for proton A (left) and B (right) fot the titration of 33 with C70

Nonlinear curve regression of the titration of 33 with C70

5.8 1H NMR Titration Experiments for clip 34

1 5.8.1 H NMR titration of 34 with C60 in chlorobenzene-d5

-4 0.35 mg of 34 was dissolved in 2 ml of chlorobenzene-d5 to give 2.03×10 M

stock solution. 600 μL of the solution was titrated against 10, 20, 30, 40, 50, 60, 70, 80,

-4 100, 150, 200, 300, 400, 500 and 1500 μL of 6.17×10 M solution of C60 in

1 chlorobenzene-d5 and the changes in H NMR spectrum was recorded after each addition.

Association constant Ka was estimated from the changes in chemical shifts using non-

linear curve fitting tool in Origin 8.0 (Chapter 4 and Table 5.3).

100

1 H NMR titration data for C60@34 in chlorobenzene-d5

C60 added (μL) [34] M [C60] M

0 0.000203 0.000000

10 0.000200 0.000010

20 0.000197 0.000020

30 0.000194 0.000029

40 0.000191 0.000039

50 0.000188 0.000048

60 0.000185 0.000056

70 0.000182 0.000065

80 0.000179 0.000073

100 0.000174 0.000088

150 0.000163 0.000124

200 0.000152 0.000154

300 0.000136 0.000206

400 0.000122 0.000247

500 0.000111 0.000281

1500 0.000058 0.000441

101

Table 5.3 (Continued)

Proton 3 (8.23 ppm) Δδ of 3 Proton 9 (3.96 ppm) Δδ of 9

8.232 0.000 3.967 0.000

8.214 0.018 3.976 0.009

8.193 0.039 3.988 0.021

8.174 0.058 3.997 0.030

8.158 0.074 4.006 0.039

8.143 0.089 4.013 0.046

8.131 0.101 4.020 0.053

8.122 0.110 4.025 0.058

8.115 0.117 4.029 0.062

8.105 0.127 4.035 0.068

8.093 0.139 4.041 0.074

8.087 0.145 4.045 0.078

8.082 0.150 4.048 0.081

8.079 0.153 4.049 0.082

8.078 0.154 4.050 0.083

8.076 0.156 4.053 0.086

102

Table 5.3 (Continued)

Proton 4 (7.93 ppm) Δδ of 4 Proton 5 (7.89 ppm) Δδ of 5

7.939 0.000 7.896 0.000

7.950 0.011 7.908 0.012

7.962 0.023 7.920 0.024

7.973 0.034 7.932 0.036

7.982 0.043 7.942 0.046

7.991 0.052 7.950 0.054

7.998 0.059 7.957 0.061

8.003 0.064 7.964 0.068

8.008 0.069 7.968 0.072

8.014 0.075 7.975 0.079

8.021 0.082 7.982 0.086

8.024 0.085 7.986 0.090

8.026 0.087 7.988 0.092

8.029 0.090 7.990 0.094

8.030 0.091 7.991 0.095

8.034 0.095 7.996 0.100

103

Table 5.3 (Continued)

Molar fraction (MR) MR x Δδ of 3 MR x Δδ of 9

1.0000 0.0000 0.0000

0.9518 0.0171 0.0086

0.9080 0.0354 0.0191

0.8681 0.0504 0.0260

0.8316 0.0615 0.0324

0.7980 0.0710 0.0367

0.7670 0.0775 0.0407

0.7383 0.0812 0.0428

0.7117 0.0833 0.0441

0.6639 0.0843 0.0451

0.5683 0.0790 0.0421

0.4968 0.0720 0.0388

0.3970 0.0595 0.0322

0.3305 0.0506 0.0271

0.2831 0.0436 0.0235

0.1163 0.0181 0.0100

104

Table 5.3 (Continued)

Molar fraction (MR) MR x Δδ of 4 MR x Δδ of 5

1.0000 0.0000 0.0000

0.9518 0.0105 0.0114

0.9080 0.0209 0.0218

0.8681 0.0295 0.0313

0.8316 0.0358 0.0383

0.7980 0.0415 0.0431

0.7670 0.0453 0.0468

0.7383 0.0473 0.0502

0.7117 0.0491 0.0512

0.6639 0.0498 0.0524

0.5683 0.0466 0.0489

0.4968 0.0422 0.0447

0.3970 0.0345 0.0365

0.3305 0.0297 0.0311

0.2831 0.0258 0.0269

0.1163 0.0111 0.0116

105

Job’s plot for protons 3 (left) and OMe (right) for the titration of 34 with C60

Job’s plot for protons 4 (left) and 5 (right) for the titration of 34 with C60

106

Nonlinear curve regression of the titration of 34 with C60 (Failed attempt)

Even after several attempts we did not observe a good fit for the titration of clip

34 with C60

0.35mg of 34 was dissolved in 1 ml of chlorobenzene-d5. 96μL of clip 34 (from

4.18×10-4M stock solution) was diluted to a concentration of 4.01×10-5 M. 600 μL of the solution (4.01×10-5 M clip 34) was titrated against 5, 10, 15, 20, 25, 30, 35, 40, 45, 50,

55, 60, 65, 70, 75, 80, 90, 100, 150, 200, 300, 400, 500 and 1500 μL of 1.17×10-4 M

1 solution of C60 in chlorobenzene-d5 and the changes in H NMR spectrum was recorded after each addition (Table 5.4).

1 H NMR titration data for 34 with C60 in chlorobenzene-d5

C60 added (μL) [34] M [C60] M

0 0.000040 0

5 0.000040 0.000001

10 0.000039 0.000002

107

Table 5.4 (Continued)

15 0.000039 0.000003

20 0.000039 0.000004

25 0.000039 0.000005

30 0.000038 0.000006

35 0.000038 0.000007

40 0.000038 0.000007

45 0.000037 0.000008

50 0.000037 0.000009

55 0.000037 0.000010

60 0.000036 0.000011

65 0.000036 0.000012

70 0.000036 0.000012

75 0.000036 0.000013

80 0.000035 0.000014

90 0.000035 0.000015

100 0.000034 0.000017

150 0.000032 0.000024

200 0.000030 0.000029

300 0.000027 0.000039

400 0.000024 0.000047

500 0.000022 0.000054

1500 0.000011 0.000084

108

Table 5.4 (Continued)

Proton 3 (8.23 ppm) Δδ of 3 Proton 4 (7.94 ppm) Δδ 0f 4

8.232 0.000 7.940 0.000

8.221 0.011 7.947 0.007

8.200 0.032 7.960 0.020

8.194 0.038 7.963 0.023

8.185 0.047 7.962 0.022

8.178 0.054 7.973 0.033

8.172 0.060 7.977 0.037

8.164 0.068 7.978 0.038

8.158 0.074 7.982 0.042

8.156 0.076 7.985 0.045

8.152 0.080 7.986 0.046

8.148 0.084 7.990 0.050

8.143 0.089 7.992 0.052

8.139 0.093 7.995 0.055

8.134 0.098 7.997 0.057

8.132 0.100 7.999 0.059

8.130 0.102 7.999 0.059

8.125 0.107 8.004 0.064

8.122 0.110 8.004 0.064

8.113 0.119 8.010 0.070

8.107 0.125 8.014 0.074

8.098 0.134 8.018 0.078

8.094 0.138 8.021 0.081

8.092 0.140 8.022 0.082

8.083 0.149 8.024 0.084 109

Table 5.4 (Continued)

Proton 5 (7.89 ppm) Δδ of 5 Proton 6 (7.63 ppm) Δδ of 6

7.897 0.000 7.635 0.000

7.904 0.007 7.641 0.006

7.917 0.020 7.652 0.017

7.921 0.024 7.657 0.022

7.923 0.026 7.661 0.026

7.928 0.031 7.663 0.028

7.937 0.040 7.670 0.035

7.938 0.041 7.673 0.038

7.942 0.045 7.675 0.040

7.943 0.046 7.677 0.042

7.947 0.050 7.678 0.043

7.949 0.052 7.682 0.047

7.951 0.054 7.683 0.048

7.954 0.057 7.685 0.050

7.958 0.061 7.687 0.052

7.957 0.060 7.688 0.053

7.960 0.063 7.689 0.054

7.963 0.066 7.691 0.056

7.964 0.067 7.694 0.059

7.971 0.074 7.698 0.063

7.974 0.077 7.704 0.069

7.978 0.081 7.707 0.072

7.981 0.084 7.709 0.074

7.983 0.086 7.711 0.076

7.984 0.087 7.715 0.080 110

Table 5.4 (Continued)

Molar fraction (MR) MR X Δδ of 3 MR X Δδ of 4

1 0.0000 0.0000

0.9761 0.0107 0.0068

0.9533 0.0305 0.0191

0.9316 0.0354 0.0214

0.9108 0.0428 0.0200

0.8909 0.0481 0.0294

0.8719 0.0523 0.0323

0.8537 0.0580 0.0324

0.8362 0.0619 0.0351

0.8194 0.0623 0.0369

0.8033 0.0643 0.0370

0.7878 0.0662 0.0394

0.7729 0.0688 0.0402

0.7585 0.0705 0.0417

0.7447 0.0730 0.0424

0.7314 0.0731 0.0432

0.7185 0.0733 0.0424

0.6941 0.0743 0.0444

0.6713 0.0738 0.0430

0.5765 0.0686 0.0404

0.5052 0.0631 0.0374

0.4050 0.0543 0.0316

0.3380 0.0466 0.0274

0.2900 0.0406 0.0238

0.1198 0.0179 0.0101 111

5.8.2 Titration of 34 with C70 in chlorobenzene-d5

-4 0.35 mg of 34 was dissolved in 2 mL of chlorobenzene-d5 to give 2.03*10 M

stock solution. 600 µL of the solution was titrated with 10, 20, 30, 40, 50, 60, 70, 80,

-4 100, 150, 200, 300, 400, 500 and 1500 µL of 3.8*10 M solution of C70 in

1 chlorobenzene-d5 and H NMR spectra were recorded after each addition( Table 5.5).

1 H NMR titration of clip34 with C70

C70 added (μL) [34] [C70]

0 0.000203 0.000000

10 0.000200 0.000006

20 0.000197 0.000012

30 0.000194 0.000018

40 0.000191 0.000024

50 0.000188 0.000029

60 0.000185 0.000035

70 0.000182 0.000040

80 0.000179 0.000045

100 0.000174 0.000054

150 0.000163 0.000076

200 0.000152 0.000095

300 0.000136 0.000127

400 0.000122 0.000152

500 0.000111 0.000173

1500 0.000058 0.000272

112

Table 5.5 (Continued)

Proton 10 (7.52 ppm) Δδ of 10 Proton 11 (7.5 ppm) Δδ of 11

7.520 0.000 7.506 0.000

7.519 0.001 7.504 0.002

7.516 0.004 7.502 0.004

7.514 0.006 7.499 0.007

7.511 0.009 7.497 0.009

7.509 0.011 7.495 0.011

7.507 0.013 7.493 0.013

7.504 0.016 7.490 0.016

7.502 0.018 7.487 0.019

7.498 0.022 7.484 0.022

7.492 0.028 7.477 0.029

7.487 0.033 7.473 0.033

7.483 0.037 7.469 0.037

7.482 0.038 7.467 0.039

7.480 0.040 7.466 0.040

7.479 0.041 7.464 0.042

113

Table 5.5 (Continued)

Proton 5 (7.90 ppm) Δδ of 5 Proton 9 (7.55 ppm) Δδ of 9

7.904 0.000 7.550 0.000

7.905 0.002 7.548 0.002

7.908 0.004 7.546 0.004

7.910 0.007 7.543 0.007

7.912 0.008 7.541 0.009

7.915 0.011 7.538 0.012

7.916 0.013 7.536 0.014

7.919 0.015 7.533 0.017

7.921 0.017 7.531 0.019

7.924 0.021 7.527 0.023

7.931 0.027 7.519 0.031

7.935 0.032 7.514 0.036

7.939 0.035 7.510 0.040

7.940 0.036 7.508 0.042

7.941 0.037 7.507 0.043

7.941 0.038 7.506 0.044

114

Table 5.5 (Continued)

Molar fraction (MR) MR X Δδ of 9 MR X Δδ of 5

1.0000 0.0000 0.0000

0.9697 0.0019 0.0017

0.9412 0.0037 0.0037

0.9144 0.0064 0.0060

0.8890 0.0080 0.0076

0.8650 0.0103 0.0097

0.8423 0.0117 0.0106

0.8207 0.0139 0.0123

0.8002 0.0152 0.0138

0.7621 0.0175 0.0157

0.6811 0.0211 0.0185

0.6157 0.0221 0.0195

0.5164 0.0206 0.0183

0.4448 0.0186 0.0162

0.3905 0.0167 0.0144

0.1760 0.0077 0.0067

Job’s plots for protons 5 (left) and 11 (right) for the titration of 34 with C70 115

Job’s plots for protons 9 (left) and 10 (right) for the titration of 34 with C70

Nonlinear curve regression of the titration of 34 with C70

(left proton 9 and right proton 10)

Nonlinear curve regression of the titration of 34 with C70

(left proton 5 and right proton 11) 116

5.8.3 Titration of 34 with PCBM in chlorobenzene-d5

-4 0.38 mg of 34 was dissolved in 2 mL of chlorobenzene-d5 to give 2.2*10 M

stock solution. 600 µL of the solution was titrated with 10, 20, 30, 40, 50, 60, 70, 80,

100, 150, 200, 300, 400, 500 and 1500 µL of 5.7*10-4 M solution of PCBM in

1 chlorobenzene-d5 and H NMR spectra were recorded after each addition( Table 5.6).

1H NMR Titration of 34 with PCBM

PC60BM added (μL) [34] M [PCBM] M

0 0.000221 0.000000

10 0.000217 0.000009

20 0.000214 0.000019

30 0.000210 0.000027

40 0.000207 0.000036

50 0.000204 0.000044

60 0.000201 0.000052

70 0.000198 0.000060

80 0.000195 0.000068

100 0.000189 0.000082

150 0.000177 0.000115

200 0.000166 0.000144

300 0.000147 0.000192

400 0.000132 0.000231

500 0.000120 0.000262

1500 0.000063 0.000412

117

Table 5.6 (Continued)

Proton 2 (8.42 ppm) Δδ of 2 Proton 3 (8.23 ppm) Δδ of 3

8.423 0.000 8.232 0.000

8.418 0.005 8.223 0.009

8.414 0.009 8.215 0.017

8.411 0.012 8.207 0.025

8.407 0.016 8.201 0.031

8.405 0.018 8.196 0.036

8.403 0.020 8.190 0.042

8.400 0.023 8.187 0.045

8.399 0.024 8.183 0.049

8.395 0.028 8.177 0.055

8.390 0.033 8.166 0.066

8.386 0.037 8.158 0.074

8.382 0.041 8.150 0.082

8.380 0.043 8.145 0.087

8.377 0.046 8.138 0.094

8.371 0.052 8.132 0.100

118

Table 5.6 (Continued)

Proton at 3.96 ppm) Δδ of 9 Proton at 4.59 ppm) Δδ of 8

3.967 0.000 4.590 0.000

3.974 0.007 4.585 0.005

3.982 0.015 4.578 0.012

3.990 0.023 4.573 0.017

3.995 0.028 4.569 0.021

4.000 0.033 4.566 0.024

4.005 0.038 4.562 0.028

4.010 0.043 4.558 0.032

4.013 0.046 4.556 0.034

4.019 0.052 4.552 0.038

4.029 0.062 4.545 0.045

4.036 0.069 4.540 0.050

4.043 0.076 4.535 0.055

4.048 0.081 4.530 0.060

4.052 0.085 4.527 0.063

4.062 0.095 4.524 0.066

119

Table 5.6 (Continued)

MR X Δδ of proton Mole fraction (MR) MR X Δδ of 3 3.96

1.0000 0.0000 0.0000

0.9583 0.0086 0.0067

0.9199 0.0156 0.0138

0.8845 0.0221 0.0203

0.8517 0.0264 0.0238

0.8213 0.0296 0.0271

0.7929 0.0333 0.0301

0.7665 0.0345 0.0330

0.7417 0.0363 0.0341

0.6967 0.0383 0.0362

0.6050 0.0399 0.0375

0.5346 0.0396 0.0369

0.4337 0.0356 0.0330

0.3648 0.0317 0.0295

0.3148 0.0296 0.0268

0.1328 0.0133 0.0126

5.9 Crystal Structure Determination of C60@34

X-ray crystals of C60@34 were attained by a slow evaporation of solutions of 34

and C60 in o-dichlorobenzene (o-DCB). Disordered solvent contribution was removed

using the SQUEEZE procedure.72 X-ray data were collected at T=90K with CuKα radiation on a Bruker Kappa APEX-II DUO diffractometer to θmax = 62.4°, yielding

12877 independent reflections. C60@34*1.5o-DCB solvate. Crystal data: monoclinic

120

C2/c, a = 20.4242(4), b = 25.5132(4), c = 32.3262(7) Å, β = 105.6720(10)°, Z = 8, R =

0.059, 1155 refined parameters.

Crystal data and structure refinement for C60@34

Identification code Sygula44 Empirical formula C135H42Cl3O2 Formula weight 1802.04 Temperature/K 90.0(5) Crystal system N/A Space group C2/c a/Å 20.4242(4) b/Å 25.5132(4) c/Å 32.3262(7) α/° 90 β/° 105.6720(10) γ/° 90 Volume/Å3 16218.5(5) Z 8 3 ρcalcg/cm 1.476 μ/mm-1 1.553 F(000) 7352.0 Crystal size/mm3 0.15 × 0.13 × 0.03 Radiation CuKα (λ = 1.54184) 2Θ range for data collection/° 8.86 to 124.88 Index ranges -23 ≤ h ≤ 22, 0 ≤ k ≤ 29, 0 ≤ l ≤ 37 Reflections collected 46382 Independent reflections 12877 [Rint = 0.0422, Rsigma = N/A] Data/restraints/parameters 12877/0/1155 Goodness-of-fit on F2 1.023 Final R indexes [I>=2σ (I)] R1 = 0.0589, wR2 = 0.1515 Final R indexes [all data] R1 = 0.0692, wR2 = 0.1574 Largest diff. peak/hole / e Å-3 0.48/-0.23

121

Fractional atomic coordinates (×104) and equivalent isotropic displacement 2 3 parameters (Å ×10 ) for C60@34.

Atom x y z U(eq) O1 7353.5(8) 4379.9(6) 5898.1(5) 28.2(4) O2 9065.5(8) 6091.7(7) 5903.2(5) 28.3(4) C1 4555.8(12) 7803.7(9) 5459.4(8) 24.8(5) C2 4116.7(12) 7373.7(9) 5473.1(8) 25.7(5) C3 3547.6(12) 7406.9(10) 5104.5(8) 27.2(5) C4 3640.9(12) 7847.6(10) 4864.9(8) 28.1(5) C5 4262.2(13) 8094.4(9) 5080.7(8) 27.4(5) C6 5247.1(13) 7792.0(9) 5648.2(8) 25.5(5) C7 5629.7(13) 8161.5(9) 5466.1(8) 29.0(6) C8 5346.3(14) 8441.3(9) 5097.9(8) 30.6(6) C9 4639.3(13) 8385.8(9) 4867.6(8) 30.1(6) C10 4310.5(15) 8474.8(10) 4419.6(9) 35.2(6) C11 3712.9(14) 8231.5(10) 4207.8(9) 34.8(6) C12 3369.5(13) 7875.3(10) 4423.2(8) 33.2(6) C13 2881.0(14) 7468.4(11) 4244.0(9) 36.3(6) C14 2787.9(13) 7043.1(11) 4480.8(9) 34.9(6) C15 3174.8(12) 6972.2(10) 4923.6(8) 29.8(6) C16 3348.8(12) 6496(1) 5166.6(8) 30.7(6) C17 3905.2(12) 6466.3(10) 5520.5(8) 27.0(5) C18 4344.7(12) 6905.0(9) 5672.6(8) 24.4(5) C19 5056.7(12) 6900.3(9) 5933.1(7) 23.6(5) C20 5498.9(12) 7339.3(9) 5924.0(7) 23.9(5) C21 6196.3(12) 7303.4(9) 6151.3(8) 25.6(5) C22 6438.9(12) 6856.3(10) 6374.2(7) 24.3(5) C23 6008.3(12) 6425.5(9) 6376.0(7) 23.6(5) C24 5331.2(12) 6445.5(9) 6162.8(7) 24.3(5) C25 6441.1(12) 6004.5(10) 6650.8(8) 26.2(5) C26 6919.7(13) 6361.1(10) 6993.4(8) 30.4(6) C27 7144.3(12) 6701.1(10) 6652.8(8) 27.3(5) C28 7395.3(12) 6257.6(9) 6418.2(7) 24.0(5) C29 6958.3(12) 5822.0(9) 6416.1(7) 22.8(5) C30 7060.0(12) 5355.3(9) 6241.2(7) 23.1(5) C31 7620.7(11) 5299.0(9) 6061.3(7) 21.5(5) C32 8057.8(12) 5735.9(9) 6061.7(7) 22.2(5) C33 7929.2(12) 6220.7(9) 6240.7(7) 23.4(5) C34 8634.3(11) 5673.6(9) 5891.4(7) 22.4(5) C35 8744.8(11) 5200.1(9) 5726.7(7) 23.1(5)

122

Table 5.8 (Continued)

C36 8304.7(12) 4768.1(9) 5719.2(7) 23.1(5) C37 7758.8(12) 4809.3(9) 5883.0(7) 23.3(5) C38 8597.1(12) 4309.1(9) 5524.1(7) 24.3(5) C39 9367.9(12) 4428.1(10) 5717.9(8) 27.5(5) C40 9319.7(12) 5001.4(10) 5545.7(7) 23.9(5) C41 8989.9(11) 4885.2(9) 5070.8(7) 22.7(5) C42 8541.8(11) 4461.5(9) 5058.5(7) 23.4(5) C43 8173.0(11) 4258.5(9) 4673.3(8) 23.6(5) C44 8237.0(11) 4476.5(9) 4284.6(7) 23.1(5) C45 8687.3(11) 4915.1(9) 4296.5(8) 24.5(5) C46 9059.8(12) 5110.4(9) 4702.2(7) 23.8(5) C47 7930.7(12) 4501.5(10) 3513.7(8) 27.5(5) C48 7443.8(13) 4501.6(10) 3109.1(8) 30.9(6) C49 7574.8(13) 4934.1(11) 2871.1(8) 32.0(6) C50 8145.3(13) 5206.4(11) 3126.9(8) 31.3(6) C51 8367.7(12) 4937.5(10) 3525.0(8) 28.3(5) C52 7805.1(12) 4278.8(9) 3871.5(8) 26.2(5) C53 7202.8(13) 3963.1(9) 3788.6(8) 28.0(5) C54 6725.2(13) 3955.9(9) 3389.4(8) 30.6(6) C55 6811.0(14) 4268.7(10) 3037.8(8) 32.0(6) C56 6313.3(14) 4476.4(11) 2665.4(8) 35.3(6) C57 6436.8(14) 4901.8(11) 2440.7(8) 36.7(7) C58 7080.1(14) 5174.0(11) 2551.1(8) 34.0(6) C59 7249.0(14) 5698.7(11) 2450.7(8) 36.6(6) C60 7810.4(14) 5961.7(12) 2698.9(8) 36.1(6) C61 8262.6(13) 5727.9(11) 3076.3(8) 32.4(6) C62 8714.0(12) 5970.7(11) 3449.3(8) 30.6(6) C63 8919.7(12) 5711.5(10) 3840.7(8) 29.2(6) C64 8712.2(11) 5181(1) 3897.1(8) 25.9(5) C65 7607.5(14) 4087.6(11) 6291.2(9) 35.2(6) C66 9590.3(14) 6121.8(12) 6306.0(9) 37.5(6) C67 7408.7(15) 6800.0(14) 4719.7(10) 50.0(8) C68 7191.8(16) 6518.8(14) 5048.1(9) 49.0(8) C69 7282.6(15) 5959.0(14) 4986.8(10) 49.6(8) C70 7556.5(15) 5908.5(16) 4610.4(11) 56.7(9) C71 7628.4(14) 6419.3(16) 4453.0(11) 55.2(9) C72 6645.3(18) 6703.2(14) 5172.5(9) 52.7(9) C73 6142.0(17) 6318.3(13) 5249.1(8) 45.8(8) C74 6236.9(17) 5791.0(13) 5191.3(8) 44.6(7)

123

Table 5.8 (Continued)

C75 6811.2(17) 5605.2(14) 5052.9(10) 52.3(8) C76 6581.2(18) 5170.5(12) 4757.6(11) 52.0(8) C77 6850.9(18) 5118.0(12) 4406.6(11) 52.6(9) C78 7341.1(16) 5491.7(14) 4328.8(12) 54.4(9) C79 7196.3(15) 5579.3(13) 3872.1(11) 47.6(8) C80 7271.2(15) 6080.4(14) 3713.0(11) 48.6(8) C81 7491.8(13) 6504.1(14) 4006.2(10) 46.0(8) C82 7130.6(16) 6973.6(14) 3826.7(11) 52.0(8) C83 6903.6(18) 7336.7(13) 4067.6(11) 54.0(9) C84 4879.4(17) 6903.3(14) 3186.6(10) 52.0(8) C85 7053.1(19) 7249.5(13) 4525.1(10) 54.6(9) C86 6466.0(19) 7427.0(12) 4665.7(11) 52.9(9) C87 6277.7(18) 7159.2(12) 4976.9(9) 47.6(8) C88 5556.4(19) 7066.7(12) 4933.6(10) 51.6(8) C89 5485.4(18) 6551.7(12) 5101.1(9) 45.7(8) C90 5653.9(17) 5472.2(12) 4978.3(10) 46.2(8) C91 5878.2(18) 5088.9(11) 4711.9(10) 47.6(8) C92 5446.4(17) 4951.1(11) 4316.7(11) 47.2(8) C93 5727(2) 4886.2(11) 3950.9(11) 52.8(9) C94 6399.9(19) 4975.1(11) 3989.5(11) 50.8(8) C95 6618.0(19) 5256.9(12) 3660.9(11) 51.8(9) C96 6138.6(18) 5445.0(12) 3304.5(10) 48.6(8) C97 6214.4(17) 5956.0(13) 3139.7(9) 44.6(7) C98 6775.0(15) 6268.8(13) 3341.2(9) 42.6(7) C99 6670.5(16) 6820.7(13) 3395.5(10) 46.2(8) C100 6038.6(19) 7040.0(13) 3261.4(10) 49.7(8) C101 5807.6(19) 7420.5(11) 3521.1(11) 49.7(8) C102 6245.2(18) 7562.0(11) 3921.7(11) 48.4(8) C103 5960(2) 7621.0(11) 4285.3(11) 56.3(9) C104 5293(2) 7539.4(11) 4246.5(12) 53.8(9) C105 5074.4(19) 7256.2(12) 4576.0(11) 50.3(8) C106 4500.2(16) 6938.7(13) 4366.7(11) 51.0(8) C107 4424.9(15) 6432.8(13) 4527.0(11) 47.4(8) C108 4923.1(16) 6244.1(13) 4898.4(9) 42.7(7) C109 5022.8(16) 5694.4(13) 4840.4(9) 43.9(7) C110 4565.0(15) 5539.4(12) 4413.8(11) 45.5(7) C111 4210.1(13) 6007.7(14) 4233.7(10) 45.3(8) C112 5104.8(19) 7336.2(12) 3481.2(11) 53.2(9) C113 4421.9(16) 6551.9(14) 3254.1(10) 49.4(8)

124

Table 5.8 (Continued)

C114 4838.9(18) 7391.6(12) 3829.7(11) 51.4(8) C115 4640.0(17) 5266.6(13) 3713.1(10) 51.6(9) C116 4782.2(17) 5179.7(13) 4166.2(11) 50.0(8) C117 4066.1(14) 6092.0(15) 3787.8(10) 49.9(8) C118 4288.4(14) 5716.0(13) 3523.7(9) 44.4(7) C119 5559.0(16) 6190.5(14) 2994.7(8) 45.5(8) C120 4507.4(15) 5994.6(13) 3193.3(9) 44.6(7) C121 5219.4(19) 5084.1(12) 3570.4(11) 52.3(8) C122 5411.8(18) 5349.8(12) 3262.7(10) 47.2(8) C123 5051.9(16) 5810.7(13) 3069.3(9) 46.4(8) C124 4138.9(14) 6599.0(15) 3628.0(11) 52.9(9) C125 4352.7(16) 7017.5(14) 3916.0(12) 54.3(9) C126 5457.9(17) 6716.1(13) 3049.1(9) 45.7(8) Ueq is defined as 1/3 of the trace of the orthogonalised UIJ tensor

2 3 Anisotropic displacement parameters (Å ×10 ) for C60@34

Atom U11 U22 U33 U23 U13 U12 O1 22.9(9) 27.0(9) 34.2(9) -1.5(7) 7.0(7) -3.8(7) O2 26.4(9) 30.1(9) 30.2(9) -1.3(7) 10.4(7) -5.6(7) C1 25.3(12) 21.3(12) 29.7(13) -5.1(10) 10.7(10) 3.8(10) C2 26.6(13) 26.1(12) 26.7(12) -3.2(10) 11.3(10) 4.5(10) C3 21.9(12) 28.4(13) 33.3(13) -1.2(10) 10.9(11) 8.4(10) C4 25.2(13) 27.9(13) 32.4(13) -1.8(10) 9.7(11) 12.1(11) C5 32.0(14) 20.3(12) 31.7(13) -0.2(10) 11.6(11) 10.2(10) C6 29.8(13) 20.2(11) 28.0(12) -6.2(10) 10.5(10) 3.3(10) C7 28.9(13) 21.7(12) 38.5(14) -6.9(10) 12.9(11) -1(1) C8 41.2(15) 15.1(11) 40.8(15) -1.1(10) 20.2(12) 1.7(11) C9 36.2(14) 18.5(12) 38.3(14) -1(1) 14.8(12) 9.2(11) C10 50.5(17) 22.1(12) 37.4(15) 5.3(11) 19.4(13) 16.7(12) C11 42.1(16) 31.3(14) 30.8(14) 4.6(11) 9.8(12) 19.7(12) C12 30.0(14) 33.2(14) 35.1(14) 0.7(11) 6.6(11) 17.8(12) C13 30.8(14) 42.7(16) 32.4(14) -1.6(12) 3.3(11) 14.6(12) C14 24.3(13) 38.8(15) 39.8(15) -5.8(12) 5.6(11) 5.5(12) C15 18.4(12) 36.2(14) 36.1(14) -5.3(11) 9.5(11) 5.6(11) C16 20.7(12) 32.5(13) 40.6(15) -3.7(11) 11.1(11) -4.6(11) C17 21.5(12) 28.2(13) 34.0(13) 1.5(10) 11.9(11) 0.4(10) C18 22.8(12) 29.1(13) 25.9(12) -2.1(10) 14.5(10) 2.1(10) C19 23.8(12) 26.6(12) 23.0(12) -2.6(9) 10.5(10) 0.4(10) 125

Table 5.9 (Continued)

C20 26.0(13) 24.3(12) 23.9(12) -5.3(9) 11.2(10) 2.1(10) C21 27.4(13) 23.4(12) 28.1(12) -5.4(10) 11(1) -2(1) C22 22.1(12) 31.1(13) 21.7(12) -6(1) 9.3(10) 1.8(10) C23 25.3(12) 28.3(12) 20.9(11) -0.8(9) 12.4(10) 3.5(10) C24 23.7(12) 26.8(12) 26.0(12) 0.4(10) 12.7(10) 0.7(10) C25 25.5(12) 30.8(13) 24.3(12) 2.2(10) 10(1) 2.7(11) C26 27.7(13) 40.2(15) 23.0(12) 0.3(11) 6.4(10) 8.8(11) C27 25.6(13) 30.9(13) 25.6(12) -5(1) 7.4(10) 0.7(11) C28 22.2(12) 30.4(13) 17.6(11) 0.5(9) 2.4(9) 3.7(10) C29 18.8(11) 30.2(13) 18.7(11) 4.9(9) 4.1(9) 3.6(10) C30 21.0(12) 26.5(12) 20.3(11) 4.7(9) 3.2(9) 0.7(10) C31 18.5(11) 27.5(12) 17.0(11) 2.9(9) 2.2(9) 0.4(10) C32 20.4(12) 26.9(12) 18.0(11) 2.5(9) 2.9(9) -1.1(10) C33 20.7(12) 28.3(12) 19.2(11) 0.5(9) 2.2(9) -3.1(10) C34 18.5(11) 27.6(12) 20.3(11) -0.2(9) 3.9(9) -5.2(10) C35 17.5(11) 32.4(13) 18.1(11) -0.3(9) 2.6(9) 0.4(10) C36 19.2(12) 29.0(12) 19.0(11) 0.4(9) 1.6(9) 0.3(10) C37 19.0(11) 26.3(12) 22.5(12) 2.1(9) 2.1(9) -3.5(10) C38 17.9(11) 27.1(12) 26.9(12) -0.1(10) 4.3(10) 1.8(10) C39 19.3(12) 35.8(14) 26.0(13) -2.4(10) 3.8(10) 2.9(10) C40 15.2(11) 33.0(13) 23.6(12) -3.3(10) 5.3(9) -0.3(10) C41 15.7(11) 26.5(12) 25.4(12) -2.6(9) 4.8(9) 3.7(10) C42 17.5(11) 26.9(12) 25.3(12) 0.2(10) 5(1) 6.5(10) C43 15.7(11) 25.4(12) 28.7(13) -3(1) 4.1(10) 5.1(10) C44 18.8(11) 23.9(12) 25.1(12) -2.0(9) 3.5(10) 8.1(10) C45 16.9(11) 29.9(13) 27.8(13) -0.9(10) 7.7(10) 7.7(10) C46 18.0(11) 27.7(12) 26.7(12) -0.2(10) 7.7(10) 4.8(10) C47 26.3(13) 29.7(13) 25.5(13) -7(1) 5(1) 11.8(11) C48 32.4(14) 32.4(14) 27.6(13) -10.4(11) 7.5(11) 13.7(11) C49 33.4(14) 40.5(15) 24.3(13) -4.5(11) 11.4(11) 11.6(12) C50 23.5(13) 47.1(16) 25.3(13) -2.7(11) 10(1) 10.8(12) C51 23.2(12) 35.3(14) 28.6(13) -3.9(11) 10.9(10) 11.0(11) C52 24.3(12) 22.9(12) 29.6(13) -7.3(10) 4.3(10) 9(1) C53 28.5(13) 23.0(12) 30.4(13) -4.4(10) 4.5(11) 9(1) C54 30.0(14) 23.0(12) 35.7(14) -12.6(10) 3.4(11) 5.9(11) C55 35.2(14) 30.6(13) 26.2(13) -11.5(10) 1.4(11) 10.3(12) C56 34.0(15) 39.6(15) 25.9(13) -12.4(11) -2.8(11) 8.9(12) C57 39.6(16) 44.3(16) 21.6(13) -9.2(11) 0.1(11) 14.3(13) C58 35.4(15) 47.6(16) 18.0(12) -5.2(11) 5.4(11) 13.4(13)

126

Table 5.9 (Continued)

C59 36.6(15) 49.0(17) 25.1(13) 5.7(12) 9.5(12) 12.0(13) C60 32.7(15) 49.3(16) 30.3(14) 7.3(12) 15.5(12) 10.5(13) C61 27.6(13) 46.0(16) 28.4(13) 2.7(11) 15.8(11) 8.8(12) C62 21.9(12) 40.4(15) 33.9(14) 6.2(11) 15.3(11) 5.0(11) C63 17.3(12) 38.6(14) 33.9(14) -1.3(11) 10.7(10) 3.7(11) C64 15.6(11) 35.9(14) 27.3(13) 0.4(10) 7.9(10) 9.2(10) C65 32.9(14) 31.9(14) 39.7(15) 10.3(11) 8.0(12) 2.3(12) C66 27.0(14) 44.5(16) 37.3(15) -5.8(12) 2.4(12) -7.7(12) C67 27.5(15) 74(2) 41.7(17) -8.6(16) -2.2(13) -25.6(16) C68 37.8(17) 70(2) 29.8(15) -4.4(14) -6.7(13) -16.2(16) C69 28.0(15) 70(2) 39.7(17) 17.6(15) -10.1(13) 2.8(15) C70 21.7(15) 86(3) 55(2) 5.0(19) -2.6(14) 14.7(16) C71 15.6(13) 87(3) 59(2) 5.6(19) 3.4(13) -11.8(15) C72 60(2) 68(2) 24.1(14) -17.7(14) 1.2(14) -19.3(18) C73 54.1(19) 66(2) 17.5(13) -3.0(13) 9.6(13) -5.8(16) C74 56.2(19) 55.6(19) 19.2(13) 12.6(12) 5.3(13) 2.3(15) C75 48.1(19) 62(2) 37.6(17) 21.0(15) -4.9(14) 11.9(16) C76 60(2) 40.3(17) 50.7(19) 21.8(14) 5.8(16) 21.6(16) C77 61(2) 39.5(17) 63(2) 19.6(15) 26.6(17) 33.0(16) C78 32.7(16) 64(2) 68(2) 10.7(18) 16.1(16) 29.3(16) C79 31.9(15) 56.6(19) 63(2) -0.3(16) 27.0(15) 21.0(14) C80 33.9(16) 64(2) 60(2) 9.1(16) 32.6(15) 9.6(15) C81 17.0(13) 75(2) 49.3(18) -2.4(16) 14.2(12) -13.1(14) C82 43.6(18) 55(2) 67(2) 3.2(16) 31.7(17) -21.8(16) C83 58(2) 48.6(18) 57(2) -2.0(15) 18.1(17) -32.5(17) C84 48.6(19) 57(2) 39.8(17) 19.8(15) -5.2(14) 9.5(16) C85 63(2) 52.4(19) 40.1(17) -4.6(14) -0.3(16) -39.9(18) C86 70(2) 35.4(16) 50.6(19) -22.6(14) 12.0(17) -21.7(16) C87 70(2) 37.0(16) 34.5(16) -21.5(13) 12.2(15) -11.6(15) C88 79(2) 41.6(17) 40.5(17) -18.8(14) 26.8(17) 5.2(17) C89 66(2) 49.6(18) 30.7(15) -8.5(13) 29.2(15) -0.6(16) C90 58(2) 45.6(17) 38.4(16) 15.0(13) 18.9(15) -3.0(15) C91 66(2) 31.6(15) 47.4(18) 16.6(13) 19.4(16) 4.8(15) C92 60(2) 21.8(14) 62(2) 7.8(13) 20.7(17) -8.7(13) C93 86(3) 18.7(13) 57(2) -5.1(13) 25.9(19) -1.1(15) C94 66(2) 24.4(14) 69(2) -4.0(14) 30.2(18) 12.3(15) C95 71(2) 36.1(16) 64(2) -4.0(15) 44.3(19) 17.4(16) C96 67(2) 45.1(17) 38.8(16) -14.7(14) 23.6(16) 7.8(16) C97 58(2) 56.5(19) 26.9(14) -9.1(13) 23.7(14) -1.5(16)

127

Table 5.9 (Continued)

C98 42.3(17) 58.0(19) 37.0(16) -1.4(14) 26.8(14) -2.7(15) C99 45.5(18) 60(2) 40.4(16) 10.4(14) 24.0(14) -13.4(15) C100 69(2) 44.3(17) 41.0(17) 12.6(14) 24.2(16) -5.6(16) C101 69(2) 29.9(15) 51.8(19) 18.2(13) 18.7(17) -0.9(15) C102 64(2) 23.4(14) 61(2) 4.1(13) 22.0(17) -13.7(14) C103 92(3) 19.0(14) 58(2) -6.5(13) 20(2) -3.8(16) C104 76(3) 24.1(15) 71(2) -1.8(14) 36(2) 14.1(16) C105 69(2) 33.4(15) 58(2) -6.1(14) 33.9(18) 16.0(15) C106 40.4(17) 53.2(19) 70(2) -1.6(16) 32.8(16) 21.7(15) C107 33.4(16) 60(2) 61(2) 6.4(16) 33.4(15) 12.8(14) C108 44.1(17) 55.8(18) 40.2(16) -4.5(14) 31.9(14) -2.9(15) C109 46.4(18) 52.8(18) 40.4(16) 9.8(14) 25.3(14) -6.3(15) C110 36.4(16) 47.6(17) 59.4(19) -0.1(15) 24.5(15) -20.8(14) C111 19.2(13) 68(2) 52.6(18) 7.1(16) 16.5(13) -6.0(14) C112 65(2) 35.8(16) 51.9(19) 17.8(14) 4.5(17) 14.8(16) C113 35.4(16) 62(2) 37.4(16) 15.4(14) -13.5(13) 1.1(15) C114 58(2) 34.0(16) 65(2) 17.1(15) 22.0(17) 26.1(15) C115 56(2) 48.7(18) 44.7(17) -5.6(14) 3.6(15) -38.6(17) C116 55(2) 44.9(17) 51.9(19) 1.8(14) 17.1(16) -25.3(16) C117 18.8(14) 77(2) 49.7(18) 8.0(17) 1.6(13) -2.7(14) C118 26.3(14) 62(2) 39.6(16) -8.6(14) -0.9(12) -21.0(14) C119 51.1(18) 68(2) 17.2(13) -3.0(13) 8.9(13) -5.2(16) C120 35.6(16) 60.0(19) 28.8(14) -3.3(13) -7.5(12) -14.2(14) C121 71(2) 31.5(15) 53.7(19) -19.2(14) 15.6(17) -16.5(15) C122 65(2) 37.4(16) 38.9(16) -19.7(13) 14.1(15) -13.9(15) C123 49.1(18) 57.8(19) 27.2(14) -13.5(13) 1.3(13) -16.9(16) C124 18.8(14) 77(2) 56(2) 10.4(18) -1.3(13) 14.4(15) C125 37.0(17) 57(2) 69(2) 8.9(17) 15.0(16) 27.9(16) C126 64(2) 49.4(18) 22.5(14) 10.4(12) 9.3(14) -4.1(16)

Bond lengths for C60@34

Atom Atom Length/Å Atom Atom Length/Å O1 C37 1.382(3) C67 C71 1.448(5) O1 C65 1.443(3) C68 C72 1.368(5) O2 C34 1.377(3) C68 C69 1.461(5) O2 C66 1.448(3) C69 C75 1.378(5) C1 C6 1.379(3) C69 C70 1.476(5) 128

Table 5.10 (Continued)

C1 C5 1.418(3) C70 C78 1.392(5) C1 C2 1.425(4) C70 C71 1.421(5) C2 C18 1.378(3) C71 C81 1.412(5) C2 C3 1.425(3) C72 C87 1.435(5) C3 C15 1.382(4) C72 C73 1.490(5) C3 C4 1.407(4) C73 C74 1.379(5) C4 C12 1.387(4) C73 C89 1.427(5) C4 C5 1.420(4) C74 C75 1.444(5) C5 C9 1.381(4) C74 C90 1.453(5) C6 C7 1.447(4) C75 C76 1.456(5) C6 C20 1.465(3) C76 C77 1.395(5) C7 C8 1.375(4) C76 C91 1.419(5) C8 C9 1.442(4) C77 C78 1.453(5) C9 C10 1.440(4) C77 C94 1.459(5) C10 C11 1.376(4) C78 C79 1.442(5) C11 C12 1.438(4) C79 C80 1.402(5) C12 C13 1.448(4) C79 C95 1.450(5) C13 C14 1.370(4) C80 C81 1.428(5) C14 C15 1.447(4) C80 C98 1.430(5) C15 C16 1.438(4) C81 C82 1.444(5) C16 C17 1.380(4) C82 C83 1.369(5) C17 C18 1.436(4) C82 C99 1.507(5) C18 C19 1.471(3) C83 C102 1.421(5) C19 C24 1.410(3) C83 C85 1.444(5) C19 C20 1.444(3) C84 C113 1.355(5) C20 C21 1.418(3) C84 C112 1.450(5) C21 C22 1.368(3) C84 C126 1.451(5) C22 C23 1.409(4) C85 C86 1.464(5) C22 C27 1.531(3) C86 C87 1.355(5) C23 C24 1.369(3) C86 C103 1.462(5) C23 C25 1.516(3) C87 C88 1.461(5) C25 C29 1.530(3) C88 C105 1.387(5) C25 C26 1.557(4) C88 C89 1.443(5) C26 C27 1.565(4) C89 C108 1.399(5) C27 C28 1.526(3) C90 C109 1.368(5) C28 C33 1.366(3) C90 C91 1.456(5) C28 C29 1.424(3) C91 C92 1.387(5) C29 C30 1.358(3) C92 C116 1.436(5) C30 C31 1.425(3) C92 C93 1.457(5)

129

Table 5.10 (Continued)

C31 C32 1.428(3) C93 C94 1.364(5) C31 C37 1.435(3) C93 C121 1.468(5) C32 C33 1.420(3) C94 C95 1.449(5) C32 C34 1.437(3) C95 C96 1.381(5) C34 C35 1.363(3) C96 C97 1.432(5) C35 C36 1.418(3) C96 C122 1.474(5) C35 C40 1.533(3) C97 C98 1.403(4) C36 C37 1.361(3) C97 C119 1.425(5) C36 C38 1.526(3) C98 C99 1.442(5) C38 C42 1.529(3) C99 C100 1.365(5) C38 C39 1.559(3) C100 C101 1.444(5) C39 C40 1.559(3) C100 C126 1.456(5) C40 C41 1.529(3) C101 C102 1.407(5) C41 C46 1.365(3) C101 C112 1.422(5) C41 C42 1.410(3) C102 C103 1.454(5) C42 C43 1.371(3) C103 C104 1.350(5) C43 C44 1.412(3) C104 C105 1.454(5) C44 C45 1.443(4) C104 C114 1.464(5) C44 C52 1.476(3) C105 C106 1.435(5) C45 C46 1.417(3) C106 C107 1.415(5) C45 C64 1.472(3) C106 C125 1.420(5) C47 C52 1.374(4) C107 C111 1.429(5) C47 C48 1.413(4) C107 C108 1.431(5) C47 C51 1.420(4) C108 C109 1.437(5) C48 C55 1.384(4) C109 C110 1.495(4) C48 C49 1.411(4) C110 C116 1.368(5) C49 C58 1.379(4) C110 C111 1.437(5) C49 C50 1.415(4) C111 C117 1.408(4) C50 C61 1.370(4) C112 C114 1.384(5) C50 C51 1.420(4) C113 C120 1.452(5) C51 C64 1.368(4) C113 C124 1.479(5) C52 C53 1.434(4) C114 C125 1.458(5) C53 C54 1.392(4) C115 C118 1.403(5) C54 C55 1.438(4) C115 C116 1.432(5) C55 C56 1.450(4) C115 C121 1.457(5) C56 C57 1.367(4) C117 C124 1.416(5) C57 C58 1.443(4) C117 C118 1.437(5) C58 C59 1.441(4) C118 C120 1.451(4) C59 C60 1.383(4) C119 C126 1.375(5)

130

Table 5.10 (Continued)

C60 C61 1.445(4) C119 C123 1.485(5) C61 C62 1.445(4) C120 C123 1.363(5) C62 C63 1.388(4) C121 C122 1.347(5) C63 C64 1.445(4) C122 C123 1.437(5) C67 C85 1.411(5) C124 C125 1.406(5)

Bond angles for C60@34

Atom Atom Atom Angle/˚ Atom Atom Atom Angle/˚ C37 O1 C65 111.37(18) C87 C72 C73 107.8(3) C34 O2 C66 112.25(19) C74 C73 C89 121.0(3) C6 C1 C5 122.5(2) C74 C73 C72 119.5(3) C6 C1 C2 123.2(2) C89 C73 C72 107.3(3) C5 C1 C2 107.9(2) C73 C74 C75 121.2(3) C18 C2 C3 122.6(2) C73 C74 C90 118.9(3) C18 C2 C1 123.1(2) C75 C74 C90 107.5(3) C3 C2 C1 107.8(2) C69 C75 C74 119.6(3) C15 C3 C4 123.3(2) C69 C75 C76 120.8(3) C15 C3 C2 122.5(2) C74 C75 C76 107.9(3) C4 C3 C2 107.9(2) C77 C76 C91 120.8(3) C12 C4 C3 122.1(2) C77 C76 C75 118.6(3) C12 C4 C5 122.6(2) C91 C76 C75 108.6(3) C3 C4 C5 108.7(2) C76 C77 C78 121.3(3) C9 C5 C1 123.3(2) C76 C77 C94 119.1(3) C9 C5 C4 122.6(2) C78 C77 C94 107.3(3) C1 C5 C4 107.8(2) C70 C78 C79 119.5(3) C1 C6 C7 114.0(2) C70 C78 C77 119.9(3) C1 C6 C20 115.8(2) C79 C78 C77 108.6(3) C7 C6 C20 128.5(2) C80 C79 C78 120.3(3) C8 C7 C6 122.9(2) C80 C79 C95 120.0(3) C7 C8 C9 121.7(2) C78 C79 C95 108.0(3) C5 C9 C10 114.5(2) C79 C80 C81 119.5(3) C5 C9 C8 114.3(2) C79 C80 C98 119.5(3) C10 C9 C8 129.3(2) C81 C80 C98 109.2(3) C11 C10 C9 122.6(3) C71 C81 C80 120.2(3) C10 C11 C12 121.8(2) C71 C81 C82 118.5(3) C4 C12 C11 114.8(2) C80 C81 C82 109.0(3) C4 C12 C13 114.6(2) C83 C82 C81 123.2(3) 131

Table 5.11 (Continued)

C11 C12 C13 129.3(2) C83 C82 C99 118.6(3) C14 C13 C12 121.9(2) C81 C82 C99 106.3(3) C13 C14 C15 122.0(3) C82 C83 C102 121.4(3) C3 C15 C16 114.8(2) C82 C83 C85 117.9(3) C3 C15 C14 114.2(2) C102 C83 C85 108.8(3) C16 C15 C14 129.4(2) C113 C84 C112 120.6(3) C17 C16 C15 121.7(2) C113 C84 C126 119.1(3) C16 C17 C18 122.7(2) C112 C84 C126 108.2(3) C2 C18 C17 114.5(2) C67 C85 C83 121.5(3) C2 C18 C19 115.6(2) C67 C85 C86 118.6(3) C17 C18 C19 128.3(2) C83 C85 C86 107.8(3) C24 C19 C20 119.2(2) C87 C86 C103 121.2(3) C24 C19 C18 120.0(2) C87 C86 C85 119.7(3) C20 C19 C18 120.6(2) C103 C86 C85 107.2(3) C21 C20 C19 119.0(2) C86 C87 C72 121.1(3) C21 C20 C6 120.3(2) C86 C87 C88 119.4(3) C19 C20 C6 120.3(2) C72 C87 C88 107.8(3) C22 C21 C20 119.8(2) C105 C88 C89 120.6(3) C21 C22 C23 121.0(2) C105 C88 C87 119.6(3) C21 C22 C27 132.4(2) C89 C88 C87 108.2(3) C23 C22 C27 106.6(2) C108 C89 C73 120.1(3) C24 C23 C22 121.0(2) C108 C89 C88 119.2(3) C24 C23 C25 132.1(2) C73 C89 C88 109.0(3) C22 C23 C25 106.8(2) C109 C90 C74 120.1(3) C23 C24 C19 120.0(2) C109 C90 C91 120.3(3) C23 C25 C29 107.24(19) C74 C90 C91 107.9(3) C23 C25 C26 99.05(19) C92 C91 C76 120.5(3) C29 C25 C26 98.37(19) C92 C91 C90 119.4(3) C25 C26 C27 94.06(18) C76 C91 C90 108.1(3) C28 C27 C22 106.76(19) C91 C92 C116 121.1(3) C28 C27 C26 98.1(2) C91 C92 C93 119.0(3) C22 C27 C26 98.58(19) C116 C92 C93 108.3(3) C33 C28 C29 121.0(2) C94 C93 C92 121.0(3) C33 C28 C27 132.3(2) C94 C93 C121 119.1(3) C29 C28 C27 106.7(2) C92 C93 C121 107.3(3) C30 C29 C28 121.3(2) C93 C94 C95 121.1(3) C30 C29 C25 132.6(2) C93 C94 C77 119.7(3) C28 C29 C25 106.0(2) C95 C94 C77 108.1(3) C29 C30 C31 119.2(2) C96 C95 C94 119.7(3)

132

Table 5.11 (Continued)

C30 C31 C32 119.5(2) C96 C95 C79 120.0(3) C30 C31 C37 121.2(2) C94 C95 C79 108.0(3) C32 C31 C37 119.3(2) C95 C96 C97 120.2(3) C33 C32 C31 119.7(2) C95 C96 C122 119.3(3) C33 C32 C34 120.9(2) C97 C96 C122 108.9(3) C31 C32 C34 119.3(2) C98 C97 C119 119.3(3) C28 C33 C32 119.2(2) C98 C97 C96 120.1(3) C35 C34 O2 121.7(2) C119 C97 C96 108.6(3) C35 C34 C32 119.1(2) C97 C98 C80 120.2(3) O2 C34 C32 119.2(2) C97 C98 C99 118.9(3) C34 C35 C36 121.6(2) C80 C98 C99 108.7(3) C34 C35 C40 131.8(2) C100 C99 C98 121.3(3) C36 C35 C40 106.5(2) C100 C99 C82 119.2(3) C37 C36 C35 121.0(2) C98 C99 C82 106.8(3) C37 C36 C38 132.3(2) C99 C100 C101 121.3(3) C35 C36 C38 106.7(2) C99 C100 C126 119.8(3) C36 C37 O1 120.9(2) C101 C100 C126 107.6(3) C36 C37 C31 119.6(2) C102 C101 C112 119.8(3) O1 C37 C31 119.4(2) C102 C101 C100 118.8(3) C36 C38 C42 106.17(19) C112 C101 C100 109.0(3) C36 C38 C39 98.62(18) C101 C102 C83 120.7(3) C42 C38 C39 98.28(19) C101 C102 C103 118.5(3) C40 C39 C38 94.58(18) C83 C102 C103 108.9(3) C41 C40 C35 105.79(18) C104 C103 C102 121.5(3) C41 C40 C39 98.33(18) C104 C103 C86 119.5(3) C35 C40 C39 98.92(19) C102 C103 C86 107.4(3) C46 C41 C42 121.2(2) C103 C104 C105 120.7(3) C46 C41 C40 132.3(2) C103 C104 C114 119.9(3) C42 C41 C40 106.5(2) C105 C104 C114 107.6(3) C43 C42 C41 120.6(2) C88 C105 C106 120.1(3) C43 C42 C38 132.4(2) C88 C105 C104 119.6(3) C41 C42 C38 107.0(2) C106 C105 C104 108.0(3) C42 C43 C44 120.0(2) C107 C106 C125 119.4(3) C43 C44 C45 119.6(2) C107 C106 C105 119.9(3) C43 C44 C52 119.6(2) C125 C106 C105 108.9(3) C45 C44 C52 120.7(2) C106 C107 C111 119.6(3) C46 C45 C44 118.5(2) C106 C107 C108 119.4(3) C46 C45 C64 120.9(2) C111 C107 C108 108.8(3) C44 C45 C64 120.5(2) C89 C108 C107 120.8(3)

133

Table 5.11 (Continued)

C41 C46 C45 120.2(2) C89 C108 C109 118.8(3) C52 C47 C48 122.3(2) C107 C108 C109 108.2(3) C52 C47 C51 124.1(2) C90 C109 C108 121.1(3) C48 C47 C51 107.7(2) C90 C109 C110 119.4(3) C55 C48 C49 123.4(2) C108 C109 C110 107.7(3) C55 C48 C47 123.1(3) C116 C110 C111 121.9(3) C49 C48 C47 108.4(2) C116 C110 C109 119.8(3) C58 C49 C48 123.2(3) C111 C110 C109 106.0(3) C58 C49 C50 122.8(3) C117 C111 C107 120.3(3) C48 C49 C50 108.2(2) C117 C111 C110 119.0(3) C61 C50 C49 123.4(2) C107 C111 C110 109.4(3) C61 C50 C51 123.6(2) C114 C112 C101 121.3(3) C49 C50 C51 107.7(2) C114 C112 C84 119.2(3) C64 C51 C50 122.7(2) C101 C112 C84 108.0(3) C64 C51 C47 123.3(2) C84 C113 C120 120.8(3) C50 C51 C47 108.1(2) C84 C113 C124 121.1(3) C47 C52 C53 114.9(2) C120 C113 C124 106.1(3) C47 C52 C44 114.7(2) C112 C114 C125 121.8(3) C53 C52 C44 129.3(2) C112 C114 C104 119.0(3) C54 C53 C52 122.1(2) C125 C114 C104 106.7(3) C53 C54 C55 121.4(2) C118 C115 C116 120.8(3) C48 C55 C54 114.5(2) C118 C115 C121 119.1(3) C48 C55 C56 113.3(3) C116 C115 C121 108.5(3) C54 C55 C56 130.6(3) C110 C116 C115 119.1(3) C57 C56 C55 122.9(3) C110 C116 C92 120.0(3) C56 C57 C58 122.5(2) C115 C116 C92 108.8(3) C49 C58 C59 114.2(3) C111 C117 C124 120.0(3) C49 C58 C57 113.9(3) C111 C117 C118 119.6(3) C59 C58 C57 130.4(2) C124 C117 C118 108.2(3) C60 C59 C58 122.1(2) C115 C118 C117 119.6(3) C59 C60 C61 122.0(3) C115 C118 C120 119.9(3) C50 C61 C62 114.2(2) C117 C118 C120 108.7(3) C50 C61 C60 114.2(3) C126 C119 C97 121.8(3) C62 C61 C60 130.2(3) C126 C119 C123 118.7(3) C63 C62 C61 121.6(2) C97 C119 C123 107.9(3) C62 C63 C64 122.3(2) C123 C120 C118 119.1(3) C51 C64 C63 114.4(2) C123 C120 C113 120.9(3) C51 C64 C45 115.5(2) C118 C120 C113 107.9(3) C63 C64 C45 128.6(2) C122 C121 C115 119.8(3)

134

Table 5.11 (Continued)

C85 C67 C68 120.5(3) C122 C121 C93 120.7(3) C85 C67 C71 119.0(3) C115 C121 C93 107.2(3) C68 C67 C71 108.1(3) C121 C122 C123 121.1(3) C72 C68 C67 118.8(3) C121 C122 C96 120.2(3) C72 C68 C69 121.3(3) C123 C122 C96 106.8(3) C67 C68 C69 108.1(3) C120 C123 C122 121.0(3) C75 C69 C68 120.0(3) C120 C123 C119 118.9(3) C75 C69 C70 120.5(3) C122 C123 C119 107.9(3) C68 C69 C70 106.7(3) C125 C124 C117 119.8(3) C78 C70 C71 120.8(3) C125 C124 C113 118.9(3) C78 C70 C69 118.9(3) C117 C124 C113 109.1(3) C71 C70 C69 108.3(3) C124 C125 C106 120.9(3) C81 C71 C70 119.7(3) C124 C125 C114 118.4(3) C81 C71 C67 119.9(3) C106 C125 C114 108.8(3) C70 C71 C67 108.9(3) C119 C126 C84 121.5(3) C68 C72 C87 121.4(3) C119 C126 C100 118.8(3) C68 C72 C73 118.5(3) C84 C126 C100 107.2(3)

Hydrogen atom coordinates (Å×104) and isotropic displacement parameters 2 3 (Å ×10 ) for C60@34

Atom x y z U(eq) H7 6097 8213 5607 35 H8 5623 8677 4992 37 H10 4515 8711 4264 42 H11 3522 8301 3911 42 H13 2617 7497 3954 44 H14 2459 6787 4350 42 H16 3073 6194 5081 37 H17 4001 6142 5670 32 H21 6494 7589 6149 31 H24 5047 6153 6170 29 H25 6192 5723 6762 31 H26A 7301 6166 7186 36 H26B 6674 6566 7164 36 H27 7471 6993 6765 33 H30 6761 5070 6239 28 H33 8211 6516 6237 28 135

Table 5.12 (Continued)

H38 8437 3950 5574 29 H39A 9509 4410 6036 33 H39B 9665 4203 5596 33 H40 9750 5211 5616 29 H43 7875 3971 4668 28 H46 9359 5399 4718 29 H53 7127 3752 4013 34 H54 6334 3740 3348 37 H56 5882 4310 2574 42 H57 6086 5023 2203 44 H59 6966 5869 2206 44 H60 7902 6307 2619 43 H62 8874 6316 3426 37 H63 9207 5889 4080 35 H65A 8076 3977 6317 53 H65B 7322 3778 6287 53 H65C 7596 4309 6537 53 H66A 9380 6119 6545 56 H66B 9850 6446 6314 56 H66C 9896 5820 6331 56

Solvent masks information for C60@34

Electron Number X Y Z Volume count 1 0.011 0.593 0.250 1903 434 2 0.008 0.391 0.750 1903 433 3 0.084 0.126 0.413 23 2 4 0.084 0.874 0.913 23 2 5 0.415 0.626 0.087 23 2 6 0.415 0.374 0.587 23 2 7 0.584 0.626 0.413 23 2 8 0.584 0.374 0.913 23 2 9 0.915 0.126 0.087 23 2 10 0.915 0.874 0.587 23 2

136

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