Synthesis and Self-Assembly of Giant Shape Amphiphiles Based on Rod-Like Polymers

Synthesis and Self-assembly of Giant Shape Amphiphiles Based on Rod-like Polymers

and Precisely Functionalized Fullerenes

A Thesis

Presented to

The Graduate Faculty of The University of Akron

In Partial Fulfillment

of the Requirements for the Degree

Master of Science

Xing Yang

May, 2017

Synthesis and Self-assembly of Giant Shape Amphiphiles Based on Rod-like Polymers

and Precisely Functionalized Fullerenes

Xing Yang

Thesis

Accepted: Approved:

Advisor Dean of the College Dr. Stephen Z.D. Cheng Dr. Eric J. Amis

Faculty Reader Dean of the Graduate School Dr. Toshikazu Miyoshi Dr. Chand Midha

Department Chair Date Dr. Coleen Pugh

ii ABSTRACT

Self-assembly is a hot phenomenon these years that many scientists focus. It is a spontaneously process that components in a system assemble themselves to get a larger functional unit. As the technological advancements increasing, the nanometer scale study of materials is going to become more and more important. A wide variety of materials can be built because of the increasingly complex structures which we get from self- assembled nanoparticles. They can be used for different purposes. One of the self- assembly particle is shape amphiphiles.[1] Shape amphiphiles are based on competing interactions and molecular segments of distinct shapes. While computer simulation has predicted intriguing self-assembly behaviors of shape amphiphiles, experimental investigation is largely unexplored. My research will be focusing on the synthesis of a precisely defined shape amphiphiles based on functionalized fullerenes (C60) and rod-like polyfluorene, where the two different types of functionalized C60 will be placed at the two ends of polyfluorene.[2] Also the assembly of as-synthesized shape amphiphiles in solution has been systematically studied. And a novel ‘caterpillar’ structure has been observed in TEM image.

iii ACKNOWLEDGEMENTS

I am really grateful to Dr. Stephen Z.D. Cheng, during my master academic period. First,

I would thank him for having me in his research group. I became mature in a his great group and learned a lot of things under his guidance. Second, I appreciate his kind help for both academic research and daily life. Whenever I had problems or confusion, he was always the one who I went to ask for help. When I was confusing about my future life and career plan, he talked with me and give suggestion, which makes me go out of confusing. I was also benefited from his attitude towards science. It is not how much you work but how much you think will decide what kind of person you will be. It has been a period of wonderful experience to work with him.

Besides, I must thank my committee member Dr. Miyoshi for his help for my research career in Akron. Dr. Miyoshi is always there to help me when I face troubles. He is very kind and he always care about students lives. Being my thesis reader and thesis defense committee, Dr. Miyoshi always makes me feel his passion for science. We had conversations always and he has great idea for my project all the time and can give me very useful suggestion all the time and it is indeed helpful.

I would also like to thank Dr. Zhiwei Lin in my group. He helped me with my project these two years and my experiment skills were all taught by him, not only synthesis skills but also physics skills. He is very kind and has patience when I first started doing something. Without his guidance, my master thesis would not be completed.

Also I want thank my parter Hui Xu, a master student in our group. We work in the same hood, and she is always ready to help others. We often exchange experiment skills in that way we improve ourselves better.

The help from other group member cannot be ignored. I should thank all the group members and it is really my honor to work in this group.

Last but not the least, I am very thankful to my parents and all my friends. You are the source of my motivation. Thank you for your powerful support and generous favors.

TABLE OF CONTENTS

Page

LIST OF FIGURES……………………………….…………………………………….viii

CHAPTER

I. INTRODUCTION…………………………..…………………………………...……...1

1.1 Self-assembly of Giant Molecule...... 1

1.2 [60]Fullerene …….………………………...……….……...…...... 3

1.2.1 Development History and Basic Background...... 3

1.2.2 Fullerene Chemistry………………………..………………………...………..5

1.3 Bingel-Hirsch Reaction………………………………….………………….………5

1.3.1 Basic Background and Mechanism…………………….…..……..………...... 5

1.3.2 Application to Fullerene Surface……….….……..……..…..………………...6

1.3 Huisgen 1,3-dipolar Cycloaddition “Click” Reaction...... 6

1.3.1 Basic Background and Mechanism……...... 6

1.3.2 Applications...... 8

1.4 Fluorene……………………………………………………..…………………….10

1.5 Huisgen 1,3-dipolar Cycloaddition “Click” Reaction ……………………………11

II. EXPERIMENTAL SECTION………………………………..…….………….……..15

2.1 Molecule Design…………………………….………………………..…...…….…15

2.2 Chemicals and Instruments……...……………………....….…….………....……..18

2.3 Synthesis Procedures………………………………………………………………20

2.3.1 Synthesis of Polyfluorene………………………...…………....…..………...20

2.3.1.1 2,7-Dibromo-9,9-dihexyl-9H-fluorene (1) ...... ……….…...... 20

2.3.1.2 2-Bromo-9,9-dihexyl-9H-fluorene (2) .....…………………….....…..21

2.3.1.3 9,9-Dihexyl-9H-fluoren-2-yl-2-boronic acid (3) .……. ……...…..…21

2.3.1.4 Trifluorene (4)……………………………….……………….……....21

2.3.1.5 Trifluorene-di-Br (5) ………………………………………………...22

2.3.1.6 Pentafluorene (6) …………………………..…...…………….…..….22

2.3.1.7 Pentafluorene-di-Br (7) …………………………………………...…22

2.3.1.8 Pentafluorene-di-Bzn-di-Br (8) ……………………………………...22

2.3.1.9 Pentafluorene-di-Bzn-di-N3 (9) ………………………………..……22

2.3.2 Synthesis of TC60-alkyne…………………....……………………...….…….23

2.3.3 Synthesis of BNC60-alkyne………………....……….………….……...…….24

2.3.4 Synthesis of BNC60-pentafluorene-TC60 by Click Reaction …………….…..25

2.3.5 Deprotection Reaction…….….………………………………...……..….….27

2 .4 Solution Self-assembly of NC60-pentafluorene-AC60…………….……….…….…29

III. RESULTS AND DISCUSSION……………………………………....…..……..…..30

IV. SUMMARY AND FUTURE WORK…………………...………………...………...38

REFERENCES……………………………………………….……….………...….....…40

APPENDIX…………………………………………….……………….…….….…...... 43

vii

LIST OF FIGURES

Figure Page

1.1 Difference between the normal and self-assembly material .……………….….…….2

1.2 The three typical giant molecules are (A) giant surfactants, (B) giant shape amphiphiles and (C) giant polyhedra, which also include nano-Janus grains.………..…..2

1.3 Time-of-flight mass spectrum of C60 produced by laser vaporization ………………..4

1.4 Process of Bingel cyclopropanation ………………………….………………………6

1.5 a) VB-structure of C60 which includ a selected array of 6 pseudooctahedral [6,6] double bonds and also the Th-symmetrical substructure; b) and c) two different views of the octahedral pattern of a hexakisadduct of C60; d) relationships of relative position for

[6,6] double bonds in a C60 adduct……………………………….……………….…..…..7

1.6 A stepwise synthesis process of Th-C66(COOEt)12……..………………………..……8

1.7 Structural formula of fluorine ……………………………………………….………9

1.8 3D structural formula of fluorene …………………………...…………………..……9

1.9 Formation of by-products ………………………………………...……………..……9

1.10 Catalyst circle for the reaction……………………………………………………...10

2.1 Self-assembly of AC60-C60 and AC60-2C60………………………..…………………12

2.2 The self-assembly process of rod-like giant molecule …………………..……..……12

2.3 The molecule design of rod-like molecule …………………………………..……....13

2.4 Rod synthetic routes of TC60 and BNC60……………………………………….....…15

viii

2.5 Rod synthetic routes of rod-like molecule…………………………………………...15

2.6 Synthetic routes of NC60-pentafluorene-AC60……………………………………….16

3.1 Mass spectra of pentafluorene-di-Bzn-di-N3…………………………………...……27

1 3.2 H NMR for TC60-pentafluorene-BNC60...... ………..….27

3.3 TEM image of NC60-pentafluorene-AC60………………………………….………...28

3.4 Cartoon of NC60-pentafluorene-AC60 pattern …………………………………...…..28

A.1 1H NMR spectra of 2-Bromo-9,9-dihexyl-9H-fluorene (2) ………………….…..…30

A.2 13C NMR spectra of2-Bromo-9,9-dihexyl-9H-fluorene (2) ……………………...…30

A.3 1H NMR spectra of 9,9-Dihexyl-9H-fluoren-2-yl-2-boroni acid (3) …………….…31

A.4 13C NMR spectra of 9,9-Dihexyl-9H-fluoren-2-yl-2-boronic acid (3) …….…….…31

A.5 1H NMR spectra of (4) Trifluorene …………………………………………...….…32

A.6 13C NMR spectra of (4) Trifluorene ……………………………………………...…32

A.7 1H NMR spectra of (5) Trifluorene-di-Br ………………………………….…….…33

A.8 13C NMR spectra of (5) Trifluorene-di-Br ………………………………….………33

A.9 1H NMR spectra of Pentafluorene ………..………………………………....…...…34

13 A.10 C NMR spectra of Pentafluorene ……………………….……………….………34

A.11 1H NMR spectra of (7) Pentafuorene-di-Br ………………………………...……..35

A.12 13C NMR spectra of (7) Pentafuorene-di-Br ……………………….……..……….35

A.13 1H NMR spectra of (8) Pentafuorene-di-Bzn-di-Br …………………………...…..36

A.14 13C NMR spectra of (8) Pentafuorene-di-Bzn-di-Br ……………….…….………..36

A.15 1H NMR spectra of (8) Pentafuorene-di-Bzn-di-Br …………….….……..….……37

A.16 13C NMR spectra of (8) Pentafuorene-di-Bzn-di-Br ………………….…...…..…..37

1 A.17 H NMR spectra of TC60-Alkyne …………………………………….…..…..…....38

13 A.18 C NMR spectra of TC60-Alkyne …………………………….………...…………38

1 A.19 H NMR spectra of BNC60-alkyne …………………………………….……..……39

1 A.20 H NMR spectra of TC60-pentafluoene-di-Bzn-di-N3 ……………….…....….…...39

13 A.21 C NMR spectra of TC60-pentafluorene-di-Bzn-di-N3 …………………...... …...40

CHAPTER I

INTRODUCTION

1.1 Self-assembly of giant molecule

Self-assembly is a hot phenomenon these years that many scientists focus. It is a spontaneously process that components in a system assemble themselves to get a larger functional unit. As the technological advancements increasing, the nanometer scale study of materials is going to become more and more important. A wide variety of materials can be built because of the increasingly complex structures which we get from self- assembled nanoparticles. They can be used for different purposes. As we know, the best situation for giant molecules is that MNP-based “nanoatoms” form giant molecules through a precision synthesis which are monodisperse. And through a collective secondary interactions, well-defined 3D supramolecular structures can be get from giant molecules such as lamellar, cylinder, BCC structures and so on. We can firmly make sure that, high properties in nature’s products can be achieved as developing precise synthetic polymers. Figure 1.1 shows the difference between the normal material and the self- assembly material.

Figure 1.1 Difference between the normal and self-assembly material

In Dr. Wen-Bin Zhang’s research, three typical giant molecule formulations are defined.

They are “giant surfactants”, “giant shape amphiphiles”, and “giant polyhedra”. Figure 2 provides examples of the three categories by cartoons. [3]

Figure 1.2 The three typical giant molecules are (A) giant surfactants, (B) giant shape

amphiphiles and (C) giant polyhedra, which also include nano-Janus grains.

The shape amphiphiles is one kind of self-assembly particles. It is predicted by scientist through simulation that it can form lots of morphologies. Shape amphiphiles are based on competing interactions and molecular segments of distinct shapes. The building blocks

2 give specific 3D shapes and they have certain geometry, symmetry. Additional parameters are provided for structural work by it. Cartoon shows Exemplary shape amphiphiles in Figure 3B. So many methods to combine components of symmetry and different shapes are provided in Dr. Zhang’s paper[3], such as sphere−cube, cube−disk dyads, sphere−disk, sphere−rod. These shapes provide very great potential for engineer design in self-assembled structures. Not only MNPs components, but also single-chain cross-linked nanorods, nanoparticles, gold nanoparticles and so on are included. We name the shape amphiphiles which are get from “giant shape amphiphiles” in line as the huge class of giant molecules. So many simulation studies has been studied on shape amphiphiles about the self-assembly by scientists, and it is predicted that it has a lot of phase behavior and also it has unusual hierarchal structures. Computer simulation really makes a great contribution for the self-assembly of persistent-shape objects because of the roadmap it provides. But there are almost no relatively reports on the experimental data for them because it is very difficult to synthesize well defined shape amphiphiles if we use traditional inorganic nanoparticles. A good thing is that with MNPs we successfully get a series of giant shape amphiphiles. And the rod-like giant shape amphiphiles studied in this paper is based on them.

1.2 [60]Fullerene

1.2.1 Development History and Basic Background

Carbon allotropes consist of diamond, graphite and fullerene. The shape of fullerene is sphere-like which is different from diamond and graphite. Fullerene can be dissolved in some organic solvents such as Toluene. Fullerene is becoming more and more important

3 because of these two unique properties in synthesis chemistry. [4]

In 1966, D.E.H Jones want to create a hollow carbon cage which is called giant fullerenes, but the bad thing is that the academic community downplayed his idea.[5] In 1970, Osawa

[6][7] proposed a spherical Ih-symmetric football structure for C60 molecule firstly. After that, scientists did a lot of researches to find out this new material C60. There was a breakthrough on fullerene in 1985. Kroto and Smalley wanted to study refractory clusters with mass spectroscopy in Rice University,. They used pulsed laser to focus on solid graphite because their wanted to stimulate carbon nucleates. Accidently, the 720 mass peak standing for C60 appeared in the mass spectra, at the same time the 840 mass peak appearing for C70.

Figure 1.3 Time-of-flight mass spectrum of C60 produced by laser vaporization

It is very amazing that fullerene is made of a combination of pentagons and hexagons. So far, the Ih-symmetrical Buckminsterfullerene C60 is the most famous, stable and abundant fullerene. Scientists have made plenty of efforts to find out the best way to get C60. Now arc process, thermal evaporation, combustion and chemical vapor deposition are the most common methods to prepare C60.

4 1.2.2 Fullerene Chemistry

Fullerene chemistry is an important part of organic chemistry. This subject is not only about the properties of fullerene but also the reactions relevant to fullerene.[8][9][10] Due to fullerene is a very new material, a lot of people try to investigate fullerene chemistry.

Two kinds of forms are used to functionalize fullerene. They both make substituent. One is outside the carbon cage called exohedral, the other is inside the carbon cage called endohedral.

Just like the football, fullerene has 12 pentagons and 20 hexagons in a C60 but it has no pentagons contact in this structure with each other. Because of the existence of nuclephiles, fullerenes can be electrophiles nucleophilic additions. It can react in electrophilic additions also.

Fullerene can have a variety of reactions. Under some conditions, fullerene can have nucleophilic addition reactions[11], pericyclic reactions[12], hydroxylation[13], electrophilic addition[14] and so on. The surface of fullerene can be functionalized. Through various reactions that can occur on fullerene we can add functional group on the surface of fullerene.

1.3 Bingel-Hirsch Reaction

1.3.1 Basic Background and Mechanism

Fullerene can have many reactions to functionalize internally and externally.

Cycloaddition to [6,6] double bonds in the fullerene core in exohedral fullerene reactions, first discovered by Bingel[15] in 1993. And it was modified by Hirsch[16]. Then, this reaction became the most important reaction which is also widely used. The Bingel-

5 Hirsch reaction can be done with the presence of bromo derivative of diethyl malonate and a base like 1,8-Diazabicyclo[5.4.0]undec-7-ene (DBU).[15] Bingel-Hirsch reaction brings fullerene functionalized groups as we need and in different areas Bingel-Hirsch reaction makes it have a widen use of its application. So it is very important.

The process of Bingel-Hirsch reaction depends on an intramolecular nucleophilic

[1] [1] substitution mechanism (SN1). Figure 4 shows a typical Bingel reaction process.

Figure 1.4 Process of Bingel cyclopropanation[1]

1.3.2 Application to Fullerene Surface

The surface of fullerene can be modified mainly by radical addition, nucleophilic addition and cycloaddition, although it may not have any surface activity itself. [1]

Cycloaddition to [6,6] double bonds is the most important way to exohedral functionalization in fullerene.[15] Cycloaddition can be done in fullerene at six positions.

Figure 1.5 a) VB-structure of C60 which includ a selected array of 6 pseudooctahedral

[6,6] double bonds and also the Th-symmetrical substructure; b) and c) two different

views of the octahedral pattern of a hexakisadduct of C60; d) relationships of relative

[17] position for [6,6] double bonds in a C60 adduct

Bingle-Hirsch reaction is very important and common to use to functionalize fullerene.

Hirsch synthesized Th-C66(COOEt)12 by using diethyl bromomalonate and NaH as a base step by step successfully.[17] Below is Figure 6 to show the stepwise synthesis process of

Th-C66(COOEt)12.

[17] Figure 1.6 A stepwise synthesis process of Th-C66(COOEt)12

We can also modify fullerene surface through the way we want. Just by changing the –

OEt group for Bingel-Hirsch reaction or some other reactions which can occur on the –

COOEt functional group we can get what we want. For example, the hydrophilic

[18] C66(COOH)12 can be obtained by the hydrolysis of Th-C66(COOEt)12. The hydrophobic and hydrophilic fullerene can be get as a result of modifying the surface through Bingel-Hirsch reaction.

1.4 Fluorene

Fluorene is a polycyclic aromatic hydrocarbon. It is combustible. And also it has a very strong fluorescence, just like its name. It is obtained from coal tar because it is the cheap way. Fluorene is insoluble in water, but it is soluble in a lot of organic solvents.

Fluorene can be used in a lot of ways. It is a precursor to get other fluorene compounds;

And also some functionalized fluorene have many different usage. The most important

8 reason for we use Fluorene it is that it can form rigid rod when link fluorene together.

Based on this property, we can use it to form rigid part in molecule design.

Figure 1.7 Structural formula of fluorine Figure 1.8 3D structural formula of fluorene

1.5 Huisgen 1,3-dipolar Cycloaddition “Click” Reaction

In 1998, the “click chemistry” was first introduced by Dr. Sharpless. But actually there are a lot of kinds of click reaction.[19] The “click reaction” we use in our experiment is the cycloaddition of azides and alkynes reaction. We use these two group to form a five- membered heterocyle. It is a very convenient process to link two reactants with each other. After this reaction a linker will be formed by the azide and alkyne.[20] But there is also a problem for this reaction. Even when cycloaddition between alkynes and azides is under a relatively very high temperature, there are always some by-products. We often get a mixture of 1,4 and 1,5 regioisomers both.[21]

Figure 1.9 Formation of by-products[21] 9 To avoid this problem, in 2002, Sharpless et al. found that when copper(I) serves as a catalyst for this reaction we could regiospecifically unite alkynes and azides to give only

1,4―disubstituted 1,2,3-trizaoles with almost no by-products. By a lot of researches they also found that Cu(II) salts like CuSO4•5H2O is better than using Cu(I) directly to improve the reaction.[21] One thing we need to mention is that oxygen must be excluded from the system during this reaction or the Cu(I) may become Cu(II).

The mechanism for the “click reaction” is shown in Figure 9. It is showing the whole process and it can be used to explain the mechanism.[21]

Figure 1.10 Catalyst circle for the reaction[21]

The first step is that Copper (I) species generated under the terminal alkynes condition.

Then the terminal hydrogen will be the most acidic one. Because of the base environment, it will be deprotonated to give a Cu acetylide intermediate. The ligand in the system is not good in stability. At last the azide will replace one ligand to generate a copper-azide- acetylide complex.

CHAPTER II

EXPERIMENTAL SECTION

2.1 Molecule Design

In our previous work, 12 carboxylic acid functionalized shouted for AC60 has been synthesized. The study on assembly of AC60-C60 and AC60-2C60 shows that they can form vesicles, cylinder, sphere structures, as showed in Figure 11. In simulation, two functionalized C60 ball linked with one rigid rod in the middle can form many interesting structures. But there are no experimental data of that kind of giant molecule. So we work with this rod-like molecule. The rod-like giant molecule is designed to have a rigid rod and each side of the rod has a ball. Functionalized fullerene is used as the ball, and pentafluorene is used as the rod. Make the two balls hydrophilic and hold different charge, and the rod is hydrophobic. In that case, dissolved rod-like giant molecules can form some regular structure in solvent. And the hydrophobic part doesn’t like water, then hydrophilic part will try their best to protect the rod part closely in the middle. So at last it will form a

‘caterpillar’ structure. Figure 2.2 shows cartoon of the structure. [3]

Figure 2.1 Self-assembly of AC60-C60 and AC60-2C60

Figure 2.2 The self-assembly process of rod-like giant molecule

Figure 2.3 The molecule design of rod-like molecule

12 The two balls are NC60 and AC60, and the rigid rod in the middle is pentafluorene. It is shown in Figure 2.3.

2.2 Chemicals and Instruments

Chemicals that were used during the synthesis work:

2,7-Dibromofluorene (97%), 2-bromofluorene (95%), 1-bromohexane (98%), 3-Azido-1- propanol (Aldrich 97%), triethylamine (Sigma-Aldrich 99%), 3-(Boc-amino)-1-propanol

(Aldrich 97%), [60]Fullerene (C60, MTR ltd., 99.5%), iodine (Aldrich 99.8%), 1,8- diazabicyclo[5.4.0]undec-7-ene (DBU, Aldrich 99%), methyl malonyl chloride (Aldrich

97%), pyridine (Sigma-Aldrich 99.8%), 4-Pentyn-1-ol (Aldrich 97%), tert-butyl bromoacetate (Aldrich 98%), malonic acid (Sigma-Aldrich 99%), CuBr (Aldrich 98%),

N,N’,N’,N’’,N’’-pentamethyldiethylenetriamine (PMDETA, Aldrich 99%), and CDCl3

(Aldrich 99.8 at %D), malonyl choloride (Aldrich 97%), hexane (Sigma-Aldrich 95%), ethyl acetate (Sigma-Aldrich 99.8%), toluene (Aldrich 99.5%) and 1,2-dichlorobenzene

(ODCB, Aldrich 99%)(Aldrich 97%).

To characterize the product, 1H and 13C NMR spectra were acquired using a Varian

Mercury 300 NMR and 500 NMR Spectrometer. Matrix-assisted laser desorption/ionization-time of flight (MALDI-TOF) mass spectra measurements were carried out on a BrukerUltraflex III TOF/TOF mass spectrometer.

2.3 Synthesis Procedures

N3-Penta-fluorene-N3 need to be synthesized. Two kinds of functionalized C60 were synthesized, protected carboxyl groups functionalized and protected amino groups

13 functionalized. The “clickable” and functionalized C60 can be obtained by Bingel-Hirsch reaction. Further click reaction is used to link two C60 and the fluorene and then final products can be gained after deprotection reaction. [22] [23]

Figure 2.4 Rod synthetic routes of TC60 and BNC60

Figure 2.5 Rod synthetic routes of rod-like molecule

Figure 2.6 Synthetic routes of NC60-pentafluorene-AC60

2.3.1.1 2,7-Dibromo-9,9-dihexyl-9H-fluorene (1)

A mixture of 1-Bromohexane (11.1 mL, 77.23 mmol) 2,7-dibromofluorene (10.0 g, 30.9 mmol) and tetrabutylammonium bromide (1.0 g, 3.1 mmol) is get in DMSO (60 mL) and

50% (w/w) aqueous NaOH (10 mL). Heat the reaction system to about 70℃ temperature.

And stir for 7 hours. After the reaction ethyl acetate (200 mL) was mixed with the reaction system in separating funnel, and filter off the NaOH precipitate. Use dilute HCl

(200 mL) to wash the organic extract as well as brine (2× 160 mL). Then evaporate the organic layer and make it dry and concentrated. After that it was purified by column chromatography using silica gel. Hexanes is the eluent. 1H NMR (CDCl3, ppm): δ 7.52,

7.43 (2 d, fluorenyl H, 6H), 1.91 (m, -CH2C5H11, 4H), 1.07 (m, -CH2(CH2)3CH3, 12H),

15 0.777 (t, -CH3, 6H), 0.583 (m, -CH2(CH2)3CH3, 4H). 13C NMR (CDCl3, ppm) δ

153.44 (fluorenyl q-C), 139.92 (fluorenyl q-C), 131.01 (fluorenyl H-C), 127.05 (fluorenyl

H-C), 122.32 (fluorenyl H-C), 121.89 (fluorenyl q-C), 56.61 (C(Ph)2(C6H13)2), 41.08

(CH2), 32.33 (CH2), 30.47 (CH2), 24.52 (CH2), 23.44 (CH2), 14.84 (CH3).

2.3.1.2 2-Bromo-9,9-dihexyl-9H-fluorene (2)

A mixture of 1-Bromohexane (20.24 mL, 142.8 mmol) and tetrabutylammonium bromide

(1.33 g, 4.1 mmol) and 2-bromofluorene (10.0 g, 40.8 mmol) in DMSO (60 mL) and 50%

(w/w) aqueous NaOH (10 mL). This reaction system needs to be stirred for 7 hours and also be heated at 70°C. Methylene dichloride (120 mL) was mixed with the reaction system, and filter off the NaOH precipitate. Dilute HCl (2 M, 200 mL) was added to wash the organic layer then with water to wash (3 × 160 mL), and organic layer need to be dried with sodium sulfate over night. Also evaporate the solvent, and then purify it by chromatography on silica gel. The eluent is hexanes. The yield 4 (15.5 g, 92.1%) and it is white yellow liquid. 1H NMR (CDCl3, ppm): δ 7.67 (m, fluorenyl H, 1H), 7.55 (d, fluorenyl H, 1H), 7.47 (m, fluorenyl H, 2H), 7.32 (d, fluorenyl H, 3H), 1.96 (m, -

CH2C5H11, 4H), 1.11 (m, -CH2(CH2)3CH3, 12H), 0.787 (m, -CH3, 6H), 0.63 (m, -

CH2(CH2)3CH3, 4H).

2.3.1.3 9,9-Dihexyl-9H-fluoren-2-yl-2-boronic acid (3)

A n-BuLi hexane solution (12.9 mL) firstly need to be mixed with 2 (10.1 g, 24.4 mmol).

Solvent is THF (100 mL) and temperature of system is -78 °C. The reaction system was stirred for around 2 h. And then trimethyl borate (14 mL) need to be added. Temperature

16 should also be -78 °C. After that system was warmed to around room temperature and the reaction system should be stirred overnight. At last dilute HCl (2 M) was used to control the pH value until the liquid was around 7. Add ethyl ether to extract the mixture; then the organic layer need to be washed with water (2 × 160 mL). Sodium sulfate was added to dry the organic layer. After evaporating the solvent, Hexanes was used to purified the residue by chromatography on silica gel. Eluent ethyl is acetate (4:1) and yield 5 (6.14 g,

66.8%) and it is white powder. 1H NMR (CDCl3, ppm): δ 8.31-8.22 (m, -B(OH)2), 2H),

7.89-7.39 (m, fluorenyl H, 7H), 2.10 (m, -CH2C5H11, 4H), 1.08-0.59 (m, -CH2C5H11,

22H).

2.3.1.4 Synthesis of (4) Trifluorene

The mixture of 3 (3.6 g), 1 (2.0 g), Pd(pph3) (0.10 g) in toluene (25 mL) and also the potassium carbonate solution (5 g, 10 mL) was stirred at about 90 °C for 2 days. After that the system was cooled to room temperature and use extraction to deal with petroleum ether. Then the organic layer was washed with water (2 × 150 mL) and use sodium sulfate to dry. As the solvent of the organic layer was evaporated off, Hexanes and CH2Cl2(15:1) was used to purified the residue by chromatography on silica gel. Yield 6 is (4.31 g, 74%).

And it is liquid. 1H NMR (CDCl3, ppm): δ 7.94-7.23 (m, fluorenyl H, 20H), 2.10 (m, -

CH2C5H11, 12H), 1.38-0.76 (m, -CH2C5H11, 66H).

2.3.1.5 Synthesis of (5) Trifluorene-di-Br

A dichloromethane (1 mL) solution of 4 (1.0 g, 1.3 mmol) was mixed with a solution of bromine (1.0 g, 6.3 mmol) also in dichloromethane (3 mL), and the system was stirred for

17 1.5 h under an N2 atmosphere. The mixture was washed with sodium thiosulfate in water until there is no red color. The organic layer was dried in anhydrous Na2SO4 and then evaporate organic layer to get 5 as yellow powder (1.1 g, 1.2 mmol, ca. 98%). 1H NMR

(CDCl3, ppm): δ 7.90-7.51 (m, fluorenyl H, 18H), 2.23 (m, -CH2C5H11, 12H), 1.38-0.76

(m, -CH2C5H11, 66H).

2.3.1.6 Synthesis of (6) Pentafluorene

The mixture of 3 (3.0 g), 5 (3.8 g), Pd(pph3) (0.12 g) in toluene (20 mL) and potassium carbonate solution (5g, 10 mL) was mixed together and stirred for about 2 d. The temperature is about 90 °C. The system was cooled to around room temperature and then extract system with ether. Separate the organic layer and then wash with water (2 × 160 mL). After that use sodium sulfate to dry it. Evaporate the solvent in the organic layer,

Hexanes and CH2Cl2(10:1) was used to purified the residue by chromatography on silica gel. Yield 6 was (5.32 g, 76%) as yellow powder. 1H NMR (CDCl3, ppm): δ 7.90-7.26

(m, fluorenyl H, 32H), 2.23 (m, -CH2C5H11, 20H), 1.38-0.75 (m, -CH2C5H11, 110H).

2.3.1.7 Synthesis of (7) Pentafuorene-di-Br

A dichloromethane solution of 6 (1.1 g, 1.4 mmol) was mixed with a dichloromethane solution of bromine (1.1 g, 6.4 mmol). The system was stirred for 2 h under an N2 atmosphere. Water was used to wash the mixture with sodium thiosulfate until there is no red color. The organic layer was dried over anhydrous Na2SO4 and then evaporate to get

7 as yellow powder (1.1 g, 1.4 mmol, ca. 100%). 1H NMR (CDCl3, ppm): δ 7.90-7.25 (m, fluorenyl H, 30H), 2.18 (m, -CH2C5H11, 20H), 1.37-0.64 (m, -CH2C5H11, 110H).

2.3.1.8 Synthesis of (8) Pentafuorene-di-Bzn-di-Br

The mixture of 7 (0.400 g), potassium carbonate solution (5 g, 10 mL) Bpin-bzn-O-

C3H6-Br (0.135 g), Pd(pph3) (0.06 g) in the toluene (20 mL) need to be stirred for 2 days.

And the temperature should be at 90 °C. After that the system was cooled to around room temperature and then use ether to extract the system. The organic layer was washed with water (2 × 160 mL), and use sodium sulfate to dry. After solvent of the organic layer was evaporated off, Hexanes and CH2Cl2(5:1) was used to purified the residue by chromatography on silica gel. Yield 8 was (0.230 g, 46%). It is yellow powder. 1H NMR

(CDCl3, ppm): δ 7.92-7.53 (m, fluorenyl H, 30H), 7.04, 7.01(2 s, Bzn H, 8H), 4.24 (t,

4H), 3.68(t, 4H), 2.43(t, 4H), 2.21 (m, -CH2C5H11, 20H), 1.38-0.75 (m, -CH2C5H11,

110H).

2.3.1.9 Synthesis of (9) Pentafuorene-di-Bzn-di-N3

The mixture of 8 (0.230g), sodium azide (0.120g) in mixed solvent of THF (7ml) and

DMF (7ml) was stirred for about 2 days. And the temperature of the reaction is 90 °C.

After the system was cooled to room temperature, dichloroform was used to extract the organic layer. Water was used to wash(2 × 150 mL) the organic layer. And sodium sulfate was used to dry. After the solvent was evaporated off, pure 9 was got with yield 9

(0.214mg, 87.3%). 1H NMR (CDCl3, ppm): δ 7.92-7.56 (m, fluorenyl H, 30H), 7.08,

7.03(2 s, Bzn H, 8H), 4.24 (t, 4H), 3.58(t, 4H), 2.23(t, 4H), 2123 (m, -CH2C5H11, 20H),

1.38-0.74 (m, -CH2C5H11, 110H).

2.3.2 Synthesis of TC60-Alkyne

C60 (500 mg, 0.69 mmol) in a round bottom flask which has three bottleneck was dissolved in toluene (500 mL). A dark condition is needed as the solution was stirred.

And it took 3 hours to make C60 completely dissolved under nitrogen so that no oxygen in the system. Malonate with One Alkyne Group (140 mg, 0.69 mmol) and I2 (177 mg, 0.69 mmol) were added into the system together. After 30mins, DBU (212 mg, 1.38 mmol) was added. The nitrogen was removed after another 1 hour. The mixture was stirred overnight in dark condition. Then toluene was removed by evaporator.

Toluene/hexane(2:1) was used to do silica gel chromatography to get monoadduct C60.

Monoadduct C60 (350 mg, 0.38 mmol) was dissolved in ODCB (60 mL) under dark and nitrogen condition for three hours. Then Malonate with Protected Carboxylic acid Groups

(1.2 g, 3.8 mmol) and I2 (967 mg, 3.8 mmol) was added into the system. DBU (1.16 g,

7.6 mmol) need to be added after another 30mins degassing. One hour later remove

Nitrogen. It took three days to react for this reaction. CH2Cl2 was used to remove extra I2 by silica gel chromatography and raw product was obtained in CH2Cl2/ethyl acetate (4:1) by silica gel chromatography also. Target product was get by silica gel chromatography in toluene/ethyl acetate (12:1).

1 H NMR (CDCl3, 300 MHz, ppm, d ): 4.65 (s, 20H), 4.37 (t, 2H), 3.88 (s, 3H), 2.32 (t,

13 2H), 1.91 (br, 2H), 1.43 (s, 90H). C NMR (CDCl3, 300 MHz, ppm, d ): 165.4, 162.9,

145.8, 140.7, 82.5, 78.6, 69.0, 68.7, 63.0, 53.4, 44.7, 27.9.

2.3.3 Synthesis of BNC60-alkyne

C60 (500 mg, 0.69 mmol) in a round bottom flask which has three bottleneck was dissolved in toluene (500 mL). A dark condition is needed as the solution was stirred.

Toluene/hexane(2:1) was used to do silica gel chromatography to get monoadduct C60.

Monoadduct C60 (350 mg, 0.38 mmol) was dissolved in ODCB (60 mL) under dark and nitrogen condition for three hours. Then Malonate with Protected Amino Groups (1.67 g,

4.0 mmol) and I2 (1.01 g, 4.0 mmol) was added into the system. after another 30mins,

DBU (1.21 g, 8.0 mmol) was added. One hour later remove Nitrogen. It took three days to react for this reaction. CH2Cl2 was used to remove extra I2 by silica gel chromatography and raw product was obtained in CH2Cl2/ethyl acetate (1:1) by silica gel chromatography also. Target product was get by silica gel chromatography in toluene/ethyl acetate (2:1).

1 H NMR (CDCl3, 300 MHz, ppm, d ): 4.35 (s, 20H), 3.14 (s, 3H), 1.91 (br, 2H), 1.43 (s,

13 90H). C NMR (CDCl3, 300 MHz, ppm, d ): 165.4, 156.2, 145.8, 140.8, 82.4, 78.5, 69.0,

68.7, 63.4, 44.8, 37.5, 27.9.

2.3.4 Synthesis of BNC60-pentafluorene-TC60 by Click Reaction

TC60-Alkyne (21 mg, 8 mmol), pentafluorene-di-Bzn-di-N3 and CuBr were mixed into a reaction flask in Toluene(8ml). Oxygen was removed during the reaction. Then

CH2Cl2/ethyl acetate (1:1) was used to have the target product TC60-pentafluorene-Bzn-

N3.

BNC60-Alkyne (18 mg, 6 mmol), TC60-pentafluorene-di-Bzn-di-N3 and CuBr were mixed into a reaction flask in Toluene(8ml). Oxygen was removed during the reaction. Then

PMDETA was added into the reaction system under nitrogen condition. Then through an overnight reaction, it was finished. Silica gel chromatography was done to get our product by CH2Cl2/ethyl acetate (1:1) was used to remove the excess TC60-pentafluorene- di-Bzn-di-N3. Then CH2Cl2/methyl (10:1) was used to have the target product TC60- pentafluorene-Bzn-N3.

2.3.5 Deprotection Reaction

Deprotection is to get amino groups and carboxylic acid groups. BNC60-pentafluorene-

TC60 was dissolved in pure CH2Cl2 (2 mL) in a vial (20mL). Then CF3COOH (1 mL) was added into it. It took two hours to get the final product in room temperature. At last solvent was removed, and the final product NC60-pentafluorene-AC60 was get.

2.4 Solution Self-assembly of NC60-pentafluorene-AC60

Sample NC60-pentafluorene-AC60 (0.5 mg) was weighted and dissolved in THF (500mg) in a vial(20mL). And slowly drop water into the vial. Also during the dropping process, the solution was stirred. The reaction system is at room temperature. Then the TEM sample was prepared.

CHAPTER III

RESULTS AND DISCUSSION

MALDI-TOF mass spectrum (Figure 3.1) of the pentafluoren-di-Bzn-di-N3 and nuclear magnetic resonance (NMR) (Figure 3.2) were the most convincing evidence to identify our product. We believe we obtain the product that we want based on the data of mass spectrum and NMR. The chemical shifts of the different protons and different carbons match what we analyze. The spectrums are shown in appendix.

For pentafluorene-di-Bzn-di-N3, the theoretical molecular weight is 2013.42 matches the molecular we get from mass spectra which is 2013.54. Together with the NMR spectra, all of these evidence convince us that the target product is obtained.

After the target product is achieved, their self-assembly behaviors in solution were studied. Below two images were the results from TEM based on NC60-pentafluorene-

AC60 dissolved in THF and dropping water slowly for about three days.

Due to the interaction between the negatively and positively charged C60, the NC60- pentafluorene-AC60 pack with each other alternatively. Therefore, a ‘caterpillar’ structure was formed in the solution and was observed under TEM, Figure 3.3.

Figure 3.1 Mass spectra of pentafluorene-di-Bzn-di-N3

1 Figure 3.2 H NMR for TC60-pentafluorene-BNC60

Figure 3.3 TEM image of NC60-pentafluorene-AC60

These novel structure is just like lamella in balk. It first arranged in line one by one to form a regular structure and then the structure they formed at first formed another bigger structure just like the cartoon shows in Figure 3.4. So we can see the stripe in TEM image which is just like the pattern on the surface of the caterpillar.

Figure 3.4 Cartoon of NC60-pentafluorene-AC60 pattern

CHAPTER IV

SUMMARY AND FUTURE WORK

In summary, synthesis work of rod-like giant molecule has been done successfully. The principle of the molecule design is to try to synthesize a type of a rod-like giant molecule that is fully hydrophilic at the two sides which can form different charges when they are dissolved in water, and hydrophobic in the middle. And that’s what drives shape amphiphile giant molecule to self-assemble under certain condition. Every synthesis step is confirmed by 1H and13C NMR spectrum. And the final pentafluorene is also confirmed by MALDI-TOF mass spectroscopy. We can firmly confirm the final product has been precisely synthesized. Self-assembled structures in solution was also characterized by

TEM. A ‘caterpillar’ structure has been observed. These novel structure is just like lamella in balk. It first arranged in line one by one to form a regular structure and then the structure they formed at first formed another bigger structure. So we can see the stripe in

TEM image which is just like the pattern on the surface of the caterpillar. Also we think different length of the rod will have different self-assembled structure. So in the future we will try to turn the length and get the length of hexfluorene and heptafluorene rod to see the structure they can form in solution.

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APPENDIX

1H NMR spectra of (2)

13C NMR spectra of (2)

1H NMR spectra of (3)

13C NMR spectra of (3)

31 1H NMR spectra of (4)

13C NMR spectra of (4)

32 1H NMR spectra of (5)

13C NMR spectra of (5)

33 1H NMR spectra of (6)

13C NMR spectra of (6)

34 1H NMR spectra of (7)

13C NMR spectra of (7)

35 1 H NMR spectra of (8)

13C NMR spectra of (8)

36 1H NMR spectra of (9)

1 H NMR spectra of (9)

37 1 H NMR spectra of TC60-Alkyne

13 C NMR spectra of TC60-Alkyne

1 H NMR spectra of BNC60-alkynes

1 H NMR spectra of TC60-pentafluorene-Bzn-N3

39 13 C NMR spectra of TC60-pentafluorene-Bzn-N3