DOCSLIB.ORG

Synthesis of Acene Based Organic Gelators. Examination of the Spectroscopical, Photochemical and Rheological Properties

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Synthesis of Acene Based Organic Gelators. Examination of the Spectroscopical, Photochemical and Rheological Properties Synthesis of acene based organic gelators. Examination of the spectroscopical, photochemical and rheological properties Vom Fachbereich für Chemie und Pharmazie der Technischen Universität Carolo-Wilhelmina zu Braunschweig zur Erlangung des Grades eines Doktors der Naturwissenschaften (Dr. rer. nat.) genehmigte D i s s e r t a t i o n von Jens Reichwagen aus Hamburg 1. Referent: Professor Dr. H. Hopf 2. Referentin: Professor Dr. M. Mazik eingereicht am: 03.02.2005 mündliche Prüfung (Disputation) am: 18.04.2005 Vorveröffentlichungen der Dissertation Teilergebnisse aus dieser Arbeit wurden mit Genehmigung der Gemeinsamen Naturwissenschaftlichen Fakultät, vertreten durch den Betreuer der Arbeit, in folgenden Beiträgen vorab veröffentlicht: Publikationen Jens Reichwagen, Henning Hopf, André Del Guerzo, Jean-Pierre Desvergne, and Henri Bouas-Laurent: Photodimers of a Soluble Tetracene Derivative. Excimer Fluorescence from the Head-to-Head Isomer, Org.Lett., 2004, 6, 12, 1899-1902. André Del Guerzo, Colette Belin, Henri Bouas-Laurent, Jean-Pierre Desvergne, Jens Reichwagen, Henning Hopf: Photochromism ans Self-Assembly of Soluble Tetracenes, Mol. Cryst. Liq. Cryst., in press. Jens Reichwagen, Henning Hopf, André Del Guerzo, Colette Belin, Henri Bouas-Laurent, Jean-Pierre Desvergne: Synthesis of 2,3-substituted tetracenes and evaluation of their self- assembling properties in organic solvents, Org. Lett., 2005, 7, 6, 971-974. Tagungsbeiträge Reichwagen, J., Hopf H., Desvergne J.-P., Bouas-Laurent H.: Synthese und Eigenschaften organischer Gelbildner; 2,3 Didecyloxytetracen (DDOA) (Poster) 13. Vortragstagung der LIEBIG-Vereinigung für Organische Chemie der Gesellschaft Deutscher Chemiker (ORCHEM 2002), Bad Nauheim (2002). Reichwagen, J., Hopf, H., Del Guerzo, A. Desvergne, J.-P., Bouas-Laurent, H.: Alkoxiacene: Spektroskopie, Gel-Bildung und Photochemie einer variablen Substanzklasse (Poster) Jahrestagung der GDCh 2003, München (2003). André Del Guerzo, Jens Reichwagen, Henning Hopf, Colette Belin, Henri Bouas-Laurent, Jean-Pierre Desvergne: Self-Assembled Fibers with Tunable Optical Properties: Organogels of Anthracene and Tetracene Derivatives (Poster), HRSMC & EPA Summer School "New Perspectives in Photochemistry" Egmond aan Zee (2003). André Del Guerzo, Colette Belin, Henri Bouas-Laurent, Jean-Pierre Desvergne, Jens Reichwagen, Henning Hopf: Self-Assembling and Photochemical Properties of soluble Tetracenes, XXth IUPAC Symposium on Photochemistry, Granada (2004). Del Guerzo, A., Belin, C., Bouas-Laurent, H., Desvergne, J.-P., Reichwagen, J., Hopf, H.: Photochromism and Selfassembling of Soluble Tetracene Derivatives (Poster), ISOP'04, Arcachon (2004) Die vorliegende Arbeit wurde in der Zeit von Oktober 2001 bis November 2004 am Institut für Organische Chemie der Technischen Universität Braunschweig unter der Leitung von Prof. Dr. H. Hopf angefertigt. This study could not have been carried out and completed without the help of numerous persons. I would like to express my sincere gratitude to Prof. Dr. Henning Hopf for the possibility to perform this study, for his encouragement, advice and his interest. Further, I am very grateful to Prof. Dr. Monika Mazik for agreeing to be the co-referee of my thesis. For the opportunity to study and do research at the Université Bordeaux in 2002 and 2003, I would like to thank Prof. Dr. Henri Bouas-Laurent and Prof. Dr. Jean-Pierre Desvergne. I am very grateful to Ms. Petra Holba-Schulz for the measurement of high resolution and 2D NMR spectra; Ms. Karin Kadhim for measuring UV and IR spectra; Dr. Ulrich Papke and Ms. Doris Döring for the measurement of high and low resolution mass spectra. For the measurement of AFM and fluorescence spectra, as well as valuable discussions about photophysical techniques, I am thankful to Mme. Colette Belin and Dr. André Del Guerzo. I would like to express further my sincere gratitude to Dr. Kerstin Ibrom for many valuable discussions about my work in general and about NMR spectroscopy. For financial support of this study, I would like to thank the "Fonds der Chemischen Industrie". Last, but nor least, I thank all my colleagues for the incountable valuable discussions, the support and the enjoyable working atmosphere I experienced throughout these years. Table of contents Table of contents ........................................................................................................................ 5 1 Introduction ........................................................................................................................ 1 2 Polyacenes as low molecular mass gelators....................................................................... 3 2.1 Introduction ................................................................................................................3 2.2 Classes of organogelators........................................................................................... 4 2.2.1 Fatty acid derivatives ......................................................................................... 4 2.2.2 Steroid derivatives.............................................................................................. 5 2.2.3 Anthryl derivatives............................................................................................. 6 2.2.4 Gelators containing steroidal and condensed aromatic rings ............................. 7 2.2.5 Amino acid type organogelators ........................................................................ 9 2.2.6 Organometallic compounds.............................................................................. 11 2.2.7 Miscellaneous types of gelators ....................................................................... 12 2.2.8 Two component systems .................................................................................. 14 2.3 Synthesis of gel forming tetracenes ......................................................................... 15 2.3.1 Synthetic strategies........................................................................................... 15 2.3.1.1 Strategy A..................................................................................................... 16 2.3.1.2 Strategy B..................................................................................................... 19 2.3.1.3 Strategy C..................................................................................................... 20 2.4 Retrosynthesis of 2,3-dialkoxy-tetracenes (2) via aldol condensation, second approach ............................................................................................................................... 22 2.5 Synthesis of 2,3-dialkoxy-tetracenes (2).................................................................. 24 2.5.1 Explanation of the individual synthetic steps................................................... 25 2.5.1.1 2,3-Dimethoxy-buta-1,3-diene (37) ............................................................. 25 2.5.1.2 6,7-Dimethoxy-1,4-naphthoquinone (58). ................................................... 25 2.5.1.3 Reduction of 6,7-dimethoxy-1,4-naphthoquinone (58)................................ 27 2.5.1.4 Condensation of 1,4-dihydroxy-6,7-dimethoxy-naphthalene (57) with phthalic dialdehyde (46)............................................................................................... 28 2.5.1.5 Demethylation of 2,3-dimethoxy-tetracene-5,12-quinone (42). .................. 33 2.5.1.6 Alkylation of 2,3-dihydroxy-tetracene-5,12-quinone (35)........................... 38 2.5.1.7 Reduction of 2,3-dialkoxy-tetracene-5,12-quinones (61) ............................ 43 2.5.2 Variations of the synthesis ............................................................................... 49 2.6 Synthesis of gel forming pentacenes........................................................................ 50 2.6.1 Introduction ...................................................................................................... 50 2.7 Retrosynthesis of 2,3-dialkoxypentacenes (74) ....................................................... 51 2.8 Synthesis of 2,3-dialkoxy-pentacenes (74) .............................................................. 52 2.8.1 Explanation of the individual synthetic steps................................................... 52 2.8.1.1 Synthesis of naphthalene-2,3-dialdehyde (52) ............................................. 53 2.8.1.2 Synthesis of 2,3-dimethoxy-5,14-pentacene-quinone (77) .......................... 55 2.8.1.3 Demethylation of 2,3-dimethoxy-pentacene-5,14-quinone (77).................. 57 2.8.1.4 Alkylation of 2,3-dihydroxy-pentacene-5,14-quinone (76) ......................... 57 2.8.1.5 Reduction of 2,3-dialkoxy-pentacene-5,14-quinones (75)........................... 60 2.9 Synthesis of gel forming anthracenes....................................................................... 64 2.9.1 Introduction ...................................................................................................... 64 2.10 Retrosynthesis .......................................................................................................... 64 2.11 Synthesis of 2,3-didecyloxy-anthracene (1)............................................................. 65 2.11.1 Explanation of the individual synthetic steps................................................... 65 2.11.1.1 Synthesis of 2,3-dimethoxy-anthra-9,10-quinone (38) ............................ 65 2.11.1.2 Demethylation of 2,3-dimethoxy-9,10-anthraquinone
Load more

Recommended publications
  • Appendix 1 Table of Contents
    @ECHA EUROPEAN CHEMICALS AGENCY Appendix 1 Table of Contents: Supplementary Table C:Substances on Annex II of the Cosmetic Products Regulation ... 1 Supplementary Table D: Substances proposed to be restricted due their use restriction in CPR Annex IV column 9..,,.. 119 Supplementary Table E: Substances allowed in tattoo inks subject to the conditions specified in CPR Annex IV columns h and i ......r29 Annankatu 18. P.O. Box 400, FI-00121 Helsinki, Finland I Tel. +358 9 686180 | Fax +358 9 68618210 | echa.europa.eu ANNEX XV RESTRICTION REPORT - SUBSTANCES IN TATTOO INKS AND PERMANENT MAKE UP Su lemen Table C:Substances on Annex II of the Cosmetic Products Re ulationl Substance EC# cAs # Substance EC# cAs # R T T T A- s c R I T Name Name e b b b II s M 7 c I s I I I #4 5 6 D 9 2 1 2 3 a 3 3 3 N-(s- Chlorobenzoxa zol-2- 35783- vl)acetamide 57-4 1 (2- Acetoxyethyl)t rimethylammo (2- nium acetoxyethyl hydroxide )trimethyla 200- (Acetylcholine) 200- mmonium 124-9 5 1-84-3 and its salts t2a-9 51-84-3 2 Deanol Deanol 222- 3342- aceglumate 222- 3342- aceqlumate 085-5 61-8 (INN) 085-5 61-8 3 Spironolacto 200- Spironolactone 200- ne 133-6 52-O1-7 rINN) 133-6 52-0L-7 4 14-(4- Hydroxy-3- iodophenoxy)- 3,5- diiodophenylla cetic acid (Tiratricol 200- (INN)) and its 200- Tiratricol 086- 1 5r-24-7 salts 086- 1 5l-24-7 5 Methotrexat 200- Methotrexate 200- e 413-8 59-05-2 (INN) 413-8 59-05-2 6 Aminocaproic Aminocaproi 200- acid (INN) and 200- c acid 469-3 60-32-2 its salts 469-3 60-32-2 7 Cinchophen (rNN), its salts, derivatives and salts of 205- 132-60- these 205- 132-60- Cinchophen 067-r 5 derivatives 067-l 5 Thyropropic acid (INN) and its salts 5L-26-3 9 Trichloroacet 200- Trichloroacetic 200- ic acid 927-2 75-03-9 acid 927-2 76-03-9 l0 Aconitum napellus L.
    [Show full text]
  • Synthesis and Properties of Heterocyclic Acene Diimides
    ORGANIC LETTERS XXXX Synthesis and Properties of Heterocyclic Vol. XX, No. XX Acene Diimides 000–000 Cheng Li,†,‡ Chengyi Xiao,†,‡ Yan Li,*,† and Zhaohui Wang*,† Beijing National Laboratory for Molecular Sciences, Key Laboratory of Organic Solids, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China, and University of Chinese Academy of Sciences, Beijing 100049, China [email protected]; [email protected] Received December 27, 2012 ABSTRACT A series of heterocyclic acene diimides were synthesized effectively based on the condensation of o-phenylenediamine, 1,2-benzenedithiol, and 2-aminothiophenol with 2,3,6,7-tetrabromo-1,4,5,8-naphthalene tetracarboxylic diimide. The diimides exhibit interesting optical and electrical properties with one of them showing a hole mobility up to 0.02 cm2 VÀ1 sÀ1. In recent years, naphthalene tetracarboxylic diimides has been applied as high-performance solution-deposited (NDIs, 1, Figure 1) and their core-expanded derivatives ambipolar organic transistors.2 In contrast, the expansion have attracted a great deal of attention due to their of the π-system along the lateral position of NDIs has been interesting electro-optical properties and potential appli- demonstrated only recently due to the synthetic difficulties. cations as organic semiconductors in organic electronics.1 Recently, the synthesis of tetracene tetracarboxylic The π-skeleton of NDIs could be expanded along two diimides based on two methods of direct double ring directions: the peri position (1, 4, 5, 8) and the lateral extension of electron-deficient NDIs involving metal- position (2, 3, 6, 7). The expansion of the π-system along lacyclopentadienes and bismuth-triflate-mediated double- the peri position has been studied for many decades cyclization reaction of acid chlorides and isocyanates has because it induces impressive bathochromic shifts and been reported, which displays dramatic bathochromic shifts, smaller energy band gaps, and is a promising can- 3 † Institute of Chemistry, Chinese Academy of Sciences.
    [Show full text]
  • Chemistry of Acenes, [60]Fullerenes, Cyclacenes and Carbon Nanotubes
    University of New Hampshire University of New Hampshire Scholars' Repository Doctoral Dissertations Student Scholarship Spring 2011 Chemistry of acenes, [60]fullerenes, cyclacenes and carbon nanotubes Chandrani Pramanik University of New Hampshire, Durham Follow this and additional works at: https://scholars.unh.edu/dissertation Recommended Citation Pramanik, Chandrani, "Chemistry of acenes, [60]fullerenes, cyclacenes and carbon nanotubes" (2011). Doctoral Dissertations. 574. https://scholars.unh.edu/dissertation/574 This Dissertation is brought to you for free and open access by the Student Scholarship at University of New Hampshire Scholars' Repository. It has been accepted for inclusion in Doctoral Dissertations by an authorized administrator of University of New Hampshire Scholars' Repository. For more information, please contact [email protected]. CHEMISTRY OF ACENES, [60]FULLERENES, CYCLACENES AND CARBON NANOTUBES BY CHANDRANI PRAMANIK B.Sc., Jadavpur University, Kolkata, India, 2002 M.Sc, Indian Institute of Technology Kanpur, India, 2004 DISSERTATION Submitted to the University of New Hampshire in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy in Materials Science May 2011 UMI Number: 3467368 All rights reserved INFORMATION TO ALL USERS The quality of this reproduction is dependent upon the quality of the copy submitted. In the unlikely event that the author did not send a complete manuscript and there are missing pages, these will be noted. Also, if material had to be removed, a note will indicate the deletion. UMI Dissertation Publishing UMI 3467368 Copyright 2011 by ProQuest LLC. All rights reserved. This edition of the work is protected against unauthorized copying under Title 17, United States Code. ProQuest LLC 789 East Eisenhower Parkway P.O.
    [Show full text]
  • Community Soil Study
    Tonawanda Community Fund An affiliate of “The Wellness Institute of Greater Buffalo” Community Soil Study Fact Sheet In November 2012, Tonawanda Community Fund (TCF) led a preliminary study in a Tonawanda neighborhood to find out if air toxins were contaminating surface soil; and, if pollutants were present, do levels pose a health risk. TCF tested the soil for toxic chemicals on Kaufman Ave/James Ave/Sawyers Ave. streets in the Town of Tonawanda, NY. This neighborhood is located off of River Rd in the heart of Tonawanda’s industrial corridor. The study was initiated due to recent community complaints of a black gooey substance apparently coming from a close by air source and depositing on soil, vegetation and vehicles. The study gained more significance when Jackie James Creedon, TCF member and former director of the Clean Air Coalition of WNY, learned that a similar community’s surface soil in Birmingham, AL, where two foundry coke plants reside, was contaminated with a dangerous chemical called Benzo[a]pyrene (BAP). How the Soil was Sampled and Tested Ken‐Ton residents and TCF members, Charles Matteliano from TEQ Solutions, and Andrew Baumgartner, a student at University of Buffalo mentoring under Chemistry professor Dr .Joe Gardella, collected soil samples from a playground and 5 homes in the neighborhood. They also collected a background sample at Beaver Island State Park. Each soil sample, a composite of 6 sub samples, was tested at Test America (Amherst, NY) for 16 polycyclic aromatic hydrocarbon (PAH) compounds and 8 heavy metals. What Was Found Harmful Chemicals: Many chemicals were elevated above background sample.
    [Show full text]
  • Journal of Fluorine Chemistry 221 (2019) 1–7
    Journal of Fluorine Chemistry 221 (2019) 1–7 Contents lists available at ScienceDirect Journal of Fluorine Chemistry journal homepage: www.elsevier.com/locate/fluor Steric and electronic effects of3 CF conformations in acene(CF3)n derivatives T Nicholas J. DeWeerda, Eric V. Bukovskya, Karlee P. Castroa, Igor V. Kuvychkoa, ⁎ ⁎ ⁎ Alexey A. Popovb, , Steven H. Straussa, , Olga V. Boltalinaa, a Department of Chemistry, Colorado State University, Fort Collins, CO 80523, United States b Liebniz Institute for Solid State and Materials Research (IFW), Dresden 01069, Germany ARTICLE INFO ABSTRACT Keywords: The X-ray and DFT-optimized structures of the electron acceptor 2,3,6,7,9,10-anthra-cene(CF3)6 (ANTH-6-1) and Trifluoromethyl the 1/2 donor/acceptor co-crystal pyrene/(ANTH-6-1)2 are reported. These structures, along with extensive DFT PAH calculations on various conformations of ANTH-6-1 and 9,10-ANTH(CF3)2, suggest that the degree of bending of Acene the aromatic core in ANTH-6-1 and the DFT-predicted energies of ANTH-6-1 and 9,10-ANTH(CF3)2 are strongly Conformations 2 correlated with the relative eclipsed vs. staggered conformations of the CF3 groups attached to the central C(sp ) Bent pi systems carbon atoms (C9 and C10). Other literature X-ray and DFT-optimized structures of anthracene and pentacene X-ray structures 2 DFT calculations derivatives with n-C8F17 and/or CF3 substituents on the central C(sp ) atoms are analyzed and show (i) that the eclipsed vs. staggered correlation with the degree of bending of the aromatic cores may be a general phenom- enon and (ii) that molecules of this type are probably more stable when the acene core is bent than when it is planar.
    [Show full text]
  • Fullerene-Acene Chemistry
    University of New Hampshire University of New Hampshire Scholars' Repository Doctoral Dissertations Student Scholarship Spring 2007 Fullerene-acene chemistry: Part I Studies on the regioselective reduction of acenes and acene quinones; Part II Progress toward the synthesis of large acenes and their Diels-Alder chemistry with [60]fullerene Andreas John Athans University of New Hampshire, Durham Follow this and additional works at: https://scholars.unh.edu/dissertation Recommended Citation Athans, Andreas John, "Fullerene-acene chemistry: Part I Studies on the regioselective reduction of acenes and acene quinones; Part II Progress toward the synthesis of large acenes and their Diels-Alder chemistry with [60]fullerene" (2007). Doctoral Dissertations. 363. https://scholars.unh.edu/dissertation/363 This Dissertation is brought to you for free and open access by the Student Scholarship at University of New Hampshire Scholars' Repository. It has been accepted for inclusion in Doctoral Dissertations by an authorized administrator of University of New Hampshire Scholars' Repository. For more information, please contact [email protected]. FULLERENE-ACENE CHEMISTRY: PART I: STUDIES ON THE REGIOSELECTIVE REDUCTION OF ACENES AND ACENE QUINONES; PART II: PROGRESS TOWARD THE SYNTHESIS OF LARGE ACENES AND THEIR DIELS- ALDER CHEMISTRY WITH [60]FULLERENE VOLUME 1 CHAPTERS 1-5 BY ANDREAS JOHN ATHANS B.S. University of New Hampshire, 2001 DISSERTATION Submitted to the University of New Hampshire in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy m Chemistry May, 2007 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. UMI Number: 3 2 6 0 5 8 6 INFORMATION TO USERS The quality of this reproduction is dependent upon the quality of the copy submitted.
    [Show full text]
  • Temperature-Induced Oligomerization of Polycyclic Aromatic Hydrocarbons
    www.nature.com/scientificreports OPEN Temperature-induced oligomerization of polycyclic aromatic hydrocarbons at ambient Received: 7 June 2017 Accepted: 10 July 2017 and high pressures Published: xx xx xxxx Artem D. Chanyshev 1,2, Konstantin D. Litasov1,2, Yoshihiro Furukawa3, Konstantin A. Kokh1,2 & Anton F. Shatskiy1,2 Temperature-induced oligomerization of polycyclic aromatic hydrocarbons (PAHs) was found at 500–773 K and ambient and high (3.5 GPa) pressures. The most intensive oligomerization at 1 bar and 3.5 GPa occurs at 740–823 K. PAH carbonization at high pressure is the fnal stage of oligomerization and occurs as a result of sequential oligomerization and polymerization of the starting material, caused by overlapping of π-orbitals, a decrease of intermolecular distances, and fnally the dehydrogenation and polycondensation of benzene rings. Being important for building blocks of life, PAHs and their oligomers can be formed in the interior of the terrestrial planets with radii less than 2270 km. High-pressure transformations of polycyclic aromatic hydrocarbons (PAHs) and benzene become extremely important due to wide applications for example in graphene- and graphene-based nanotechnology1–3, synthesis of organic superconductors4, 5, petroleum geoscience, origin of organic molecules in Universe and origin of life. In particular, PAHs were found in many space objects: meteorites6–8, cometary comae9, interstellar clouds and planetary nebulas10–12. Although the prevalent hypothesis for the formation of these PAHs is irradiation-driven polymerization of smaller hydrocarbons13, alternative explanation could be shock fragmentation of carbonaceous solid material11. PAH-bearing carbonaceous material could contribute to the delivery of extraterrestrial organic materials to the prebiotic Earth during the period of heavy bombardment of the inner Solar System from 4.5 to 3.8 Ga ago14–16.
    [Show full text]
  • The Pennsylvania State University the Eberly College of Science
    The Pennsylvania State University The Eberly College of Science Department of Chemistry SYNTHESIS OF CARBON MATERIALS VIA THE COLD COMPRESSION OF AROMATIC MOLECULES AND CARBON NANOSTRUCTURES A Dissertation in Chemistry by Thomas C. Fitzgibbons 2014 Thomas C. Fitzgibbons Submitted in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy August 2014 ii The dissertation of Thomas C. Fitzgibbons was reviewed and approved* by the following: John V. Badding Professor of Chemistry Dissertation Advisor Chair of Committee Ayusman Sen Distinguished Professor of Chemistry A. Welford Castleman, Jr Evan Pugh Professor of Chemistry and Physics William B. White Professor Emeritus of Geosciences Barbara J. Garrison Shapiro Professor of Chemistry Head of the Department of Chemistry *Signatures are on file in the Graduate School iii ABSTRACT Carbon’s ability for catenation makes it a remarkable element and allows for many interesting and surprising properties and structures. Carbon can exist in one of its two thermodynamically stable bulk crystals, graphite or diamond, one of its several nanostructures: fullerene, nanotube, or graphene, or as an amorphous material with a mixed bonding pattern. Carbon also has an ability to bond heteroatoms such as hydrogen which can increase its properties and structures even further. Pressure has been shown to be able to drastically change the bonding in and structure of carbon based materials. In this dissertation I will present how pressure can be used to synthesize new amorphous hydrogenated carbons and how a battery of analytical techniques can be used to elicit the microstructure of the carbon networks. This microstructure can then be related back to the reaction conditions and more importantly the starting small molecule.
    [Show full text]
  • A Systematic Study of Acene Derivatives: Synthesis, Crystal
    A Systematic Study of Acene Derivatives: Synthesis, Crystal Structures, Optical and Electrochemical Characterizations A DISSERTATION SUBMITTED TO THE FACULTY OF THE UNIVERSITY OF MINNESOTA BY Zhuoran Zhang IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY Advisor: Christopher J. Douglas August 2018 © Zhuoran Zhang 2018 Acknowledgements Pursuing a Ph.D. degree in the U.S. has been the most unimaginable life experience for me. Being the first person to do so in my family, I feel lucky, honored, and of course, stressed. These complicated feelings probably came from my parents, who raised me up around for more than twenty years, and finally decided to push me up to the other side of the world where I could chase something higher. It must be hard for them, because they have no idea what life is like in the U.S., they probably don’t understand what a chemistry Ph.D. is. But they always respect and support my pursuit. They know it’s time to let their son take care of himself and he will be fine. Suffice to say, it is the strength that comes from their trust and hope that keeps me strong. I guess this is the unique kind of love from parents, the love that nothing could ever compare. I am deeply grateful to the selfless love, the endless support, and the sacrifice they have to make. So, thank you, Mom and Dad! I’d like to give my greatest gratitude to my advisor Prof. Chris Douglas, who has provided me with a wonderful opportunity to be a synthetic organic chemistry researcher at University of Minnesota.
    [Show full text]
  • Description of Aromaticity with the Help of Vibrational Spectroscopy: Anthracene and Phenanthrene Robert Kalescky, Elfi Kraka, and Dieter Cremer*
    Article pubs.acs.org/JPCA Description of Aromaticity with the Help of Vibrational Spectroscopy: Anthracene and Phenanthrene Robert Kalescky, Elfi Kraka, and Dieter Cremer* Computational and Theoretical Chemistry Group (CATCO), Department of Chemistry, Southern Methodist University, 3215 Daniel Avenue, Dallas, Texas 75275-0314, United States *S Supporting Information ABSTRACT: A new approach is presented to determine π-delocalization and the degree of aromaticity utilizing measured vibrational frequencies. For this purpose, a perturbation approach is used to derive vibrational force constants from experimental frequencies and calculated normal mode vectors. The latter are used to determine the local counterparts of the vibrational modes. Next, relative bond strength orders (RBSO) are obtained from the local stretching force constants, which provide reliable descriptors of CC and CH bond strengths. Finally, the RBSO values for CC bonds are used to establish a modified harmonic oscillator model and an aromatic delocalization index AI, which is split into a bond weakening (strengthening) and bond alternation part. In this way, benzene, naphthalene, anthracene, and phenanthrene are described with the help of vibrational spectroscopy as aromatic systems with a slight tendency of peripheral π-delocalization. The 6.8 kcal/mol larger stability of phenanthrene relative to anthracene predominantly (84%) results from its higher resonance energy, which is a direct consequence of the topology of ring annelation. Previous attempts to explain the higher stability of phenanthrene via a maximum electron density path between the bay H atoms are misleading in view of the properties of the electron density distribution in the bay region. ■ INTRODUCTION NMR chemical shift of an atomic nucleus is also affected by more π ff − The description of the chemical bond is one of the major than just -delocalization e ects.
    [Show full text]
  • Polycyclic Aromatic Hydrocarbons As Model Cases for Structural and Optical Studies R
    Special Issue: Review Commentary Received: 24 August 2009, Revised: 2 October 2009, Accepted: 13 October 2009, Published online in Wiley InterScience: 3 February 2010 (www.interscience.wiley.com) DOI 10.1002/poc.1644 Forever young: polycyclic aromatic hydrocarbons as model cases for structural and optical studies R. Riegera and K. Mu¨ llena* Polycyclic aromatic hydrocarbons (PAHs) are popular research subjects due to their high stability, their rigid planar structure, and their characteristic optical spectra. The recent discovery of graphene, which can be regarded as giant PAH, has further stimulated the interest in this area. For this reason, the relationship between the geometric and electronic structure and the optical spectra of PAHs are reviewed, pointing out the versatile properties of this class of molecules. Extremely stable fully-benzenoid PAHs with high optical gaps are encountered on the one side and the very reactive acenes with low optical gaps on the other side. A huge range of molecular sizes is covered from the simplest case benzene with its six carbon atoms up to disks containing as much as 96 carbon atoms. Furthermore, the impact of non-planarity is discussed as model cases for the highly important fullerenes and carbon nanotubes. The detailed analysis of the electronic structure of PAHs is very important with regard to their application as fluorescent dyes or organic semiconductors. The presented research results shall encourage developments of new PAH structures to exploit novel materials properties. Copyright ß 2010 John Wiley & Sons, Ltd. Keywords: aromaticity; dyes; photophysics; polycyclic aromatic hydrocarbons; UV/vis INTRODUCTION dramatically different optical and chemical properties are observed.
    [Show full text]
  • IUPAC Nomenclature of Fused and Bridged Fused Ring Systems
    Pure &App/. Chern., Vol. 70, No. 1, pp. 143-216, 1998. Printed in Great Britain. Q 1998 IUPAC INTERNATIONAL UNION OF PURE AND APPLIED CHEMISTRY ORGANIC CHEMISTRY DIVISION COMMISSION ON NOMENCLATURE OF ORGANIC CHEMISTRY (111.1) NOMENCLATURE OF FUSED AND BRIDGED FUSED RING SYSTEMS (IUPAC Recommendations 1998) Prepared for publication by G. P. MOSS Department of Chemistry, Queen Mary and Westfield College, Mile End Road, London, El 4NS, UK Membership of the Working Party (1982-1997): A. T. Balaban (Romania), A. J. Boulton (UK), P. M. Giles, Jr. (USA), E. W. Godly (UK), H. Gutmann (Switzerland), A. K. Ikizler (Turkey), M. V. Kisakiirek (Switzerland), S. P. Klesney (USA), N. Lozac’h (France), A. D. McNaught (UK), G. P. Moss (UK), J. Nyitrai (Hungary), W. H. Powell (USA), Ch. Schmitz (France), 0. Weissbach (Federal Republic of Germany) Membership of the Commission on Nomenclature of Organic Chemistry during the preparation of this document was as follows: Titular Members: 0. Achmatowicz (Poland) 1979-1987; J. Blackwood (USA) 1996; H. J. T. Bos (Netherlands) 1987-1995, Vice-chairman, 1991- ; J. R. Bull (Republic of South Africa) 1987-1993; F. Cozzi (Italy) 1996- ; H. A. Favre (Canada) 1989-, Chairman, 1991- ; P. M. Giles, Jr. (USA) 1989-1995; E. W. Godly (UK) 1987-1993, Secretary, 1989-1993; D. Hellwinkel (Federal Republic of Germany) 1979-1987, Vice-Chainnan, 1981-1987; B. J. Herold (Portugal) 1994- ; K. Hirayama (Japan) 1975-1983; M. V. Kisakiirek (Switzerland) 1994, Vice-chairman, 1996- ; A. D. McNaught (UK) 1979-1987; G. P. Moss (UK) 1977-1987, Chairman, 1981-1987, Vice-chairman, 1979-1981; R.
    [Show full text]