archives@tulane.edu / Abstract Condensation of 1,8,13-tris(mercaptomethyl)triptycene and tris(bromomethyl)methane yields the in,in-cyclophane 30 in 8% yield with two inwardly directed methine groups. The X-ray analysis clearly shows that it is the in,in-isomer. The proton NMR spectrum displays an obvious coupling between the two methine hydrogens, which was proved by selectively irradiation one of the apical methine proton. The coupling constant is 2.0 Hz, which is the largest through-space coupling observed so far. Based on DFT and MP2 calculations, the hydrogen-hydrogen non-bonded contact distance is estimated to be 1.50-1.53 Å. Two in,in-cyclophanes 31 and 56, containing one or two methyl groups in their central cavities, have been synthesized, crystallized and fully characterized by ¹H and ¹³C NMR spectroscopy, MALDI-TOF mass spectrometry, IR spectroscopy, and X-ray crystallography. Cyclophane 31 is the first example of an in,in-cyclophane with a methyl group inside the cavity. The IR spectrum clearly shows that the Si-H stretch is blue-shifted from 2177 cm-1 in an acyclic model to 2269 cm-1. Based on computational studies, cyclophane 31 has a very short non-bonded H---CH3 distance of about 2.30 Å. Cyclophane 56 does not have short non-bonded contact distance, but it is the first example of a macrobicyclic compound that contains two inwardly directed methyl groups. Three cyclophanes with the formula (C28H31PS3)n, where n = 1 or 2, were isolated from the base-promoted macrocyclization of tris(2-mercaptophenyl)phosphine and tris(3-bromopropyl)methane. Spectroscopic and X-ray analysis showed them to be the in,in-isomer 32, the in,out-isomer 60, and a dimeric in,out,in,out-isomer 61. Compounds 32 and 61 display approximately C3-symmetric and Ci-symmetric structures, respectively, in the crystal, but compound 60 adopts two distinct low-symmetry conformations in the solid state. In each case, the observed structures correspond to the lowest energy conformations of their respective isomers as calculated at the B3PW91/6-31G(d) level of theory. The in,in-isomer 32 displays a close contact between the phosphine in-lone pair and the in-methine group, with through-space spin-spin coupling constants of JPH = 9 Hz and JPC = 24 Hz, the latter of which appears to be the largest reported phosphorus-carbon through-space coupling constant. Dodecaphenyltetracene (75), the largest perphenylacene yet prepared, was synthesized from known tetraphenylfuran, hexaphenylisobenzofuran, and 1,2,4,5-tetrabromo-3,6-diphenylbenzene in three steps. The X-ray structure of the deep red, highly luminescent 75 shows it to be a D2-symmetric molecule with an end-to-end twist of 97o. The central acene is encapsulated by the peripheral phenyl substituents, and as a result, the molecule is relatively unreactive and even displays reversible electrochemical oxidation and reduction. Decaphenylphenanthrene (77), the first nonlinear perphenyl polycyclic aromatic hydrocarbon to be prepared so far, has been made from tetraphenylfuran and 1,2,3,4-tetrabromo-5,6-diphenylbenzene in two steps. The X-ray structure contains two independent molecules of 77, and each of them ppssesses approximate C2 symmetry in the crystal. / 1 / yonglong xiao

A series of acene-fused porphyrins and 1,10-phenanthroline-fused porphyrins were synthesized and characterized via NMR spectroscopy and mass spectrometry. The acene-fused porphyrins exhibit unique optoelectronic properties, most notably they exhibit highly red-shifted absorption bands. The 1,10-phenanthroline-fused porphyrins are of interest for their ability to bond to as variety of metals to form chelation complexes.

Thesis advisor: Shih-Yuan Liu / This dissertation describes progress in the field of polycyclic boron- nitrogen-containing systems, especially for potential application in organic-based optoelectronic devices and hydrogen storage materials. The replacement of a BN unit for a CC unit organic compounds (BN/CC isosterism) can have a profound effect on the electronic structure and even function of a given molecular topology without changing its physical structure very much. Direct comparison between a BN-containing molecule and its direct all-carbon analogue is crucial to establishing the origin of these differences. The synthesis and optoelectronic characterization of boron- nitrogen-containing analogues of naphthalene, anthracene, and tetracene are disclosed. Also examined herein is the aromatic Claisen rearrangement applied to an azaboryl allyl ether. Finally, the chemistry of saturated BN heterocycles, including an iridium-catalyzed transfer dehydrogenation method for synthesizing BN-fused azaborines. Also disclosed is the actual application of these cyclic amine-boranes in supplying hydrogen for a proton exchange membrane (PEM) fuel cell. / Thesis (PhD) — Boston College, 2017. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Chemistry.

La coordinación selectiva del oro a los triples enlaces fue la chispa que desencadenó la fiebre del oro en la química organometálica. Una amplia gama de sustratos han sido empleados pero ha sido recientemente que los cicloheptatrienoshan sido sometidos a transformaciones químicas catalizadas por oro. Se ha determinado que la reacción de alquinilcicloheptatrienos catalizada por Au(I) y Au (III) produce indenos 2- y 1-substituidos, respectivamente. En el mecanismo de esta reacción interviene un intermediario catiónico de tipo barbaralilo, sin precedentes en este tipo de química. Asimismo se ha intentado desarrollar una metodología para la síntesis de acenos por medio de una ciclación catalizada por oro, así como la síntesis de buckybowls a partir de derivados alquinílicos de la truxentriona.

No description available.

Inorganic materials have dominated electronic applications such as photovoltaic cells, thin film transistors (TFTs) and light emitting diodes (LEDs). However developments in the field of organic electronics over the past three decades have enabled the use of organic materials in these devices. While significant improvements have been made to improve their electronic properties there are several road blocks towards commercial application. One of the significant obstacles is the poor charge carrier mobility associated with organic semiconductors processed by well established printing methods. The goal of my research project is to improve the charge carrier mobility of solution cast films of acene semiconductors by partial halogenation and heteroatom substitution. Spin coated films of triisopropylsilylethynylated difluoropentacene exhibited higher hole mobility compared to TIPS pentacene due to contact induced nucleation of pentacene on perfluorobenzenethiol treated gold electrodes. The success of this project allowed me to further investigate the effect of degree of fluorination on the electronic properties of pentacene. A series of trialkylsilylethynylated tetrafluoro and octafluoropentacenes were synthesized and their performances in thin film transistors and solar cells were explored. Solar cells made from these materials using poly(3-hexylthiophene) as donor exhibited poor open circuit voltages (Voc) resulting in low power conversion efficiency (PCE). Better device performances were achieved using pentacenes having single halogen substituent. In order to improve the charge carrier mobility in TFTs soluble trialkylsilylethynylated hexacenes were explored. However these molecules exhibited a greater tendency to photo-dimerize in solution and solid state. Partial halogenation was used as a tool to improve the solution stability of reactive hexacene. The improved solution stability of partially halogenated hexacenes allowed me to successfully extend this approach to heptacene and nonacene. Finally a series of new trialkylsilylethynylated anthradiselenophenes were synthesized to improve molecular ordering in the solid state by increasing non-bonding Se – Se interaction. However single crystal x-ray diffraction studies revealed no such interaction between the acene chromophore resulting in poor device performance.

Our group has previously shown that small changes to molecular structure result in large changes to device properties and stability in organic electronic applications. By functionalizing aromatic heteroacenes with group 14 and group 16 elements, it is possible to control morphology and improve stability for a variety of applications such as thin film transistors and solar cells. Functionalization within the heteroacene core led to changes in electronic structure as observed by electrochemistry and light absorption. By substituting down the periodic table, the carbon heteroatom bond length increased, leading to subtle changes in crystal packing. Absorption maxima were red-­‐shifted and stability to light decreased. Substitution of group 14 elements to the solubilizing ethynyl groups attached to the heteroacene also had an effect on crystallization and stability. Substitution of silicon with carbon decreased solubility as well as stability to light. Substitution with germanium also decreased stability to light, but close contacts within the crystal structure and solubility in nonpolar organic solvents increased.

Acenes have been explored by a number of research groups in the field of organic electronics with a particular emphasis on transistor materials. This group has been actively studying acene‐based organic semiconductors for more than a decade using a crystal engineering approach and has developed acene derivatives for applications in field‐effect transistors, light‐emitting diodes, and photovoltaics. In addition to organic electronics, crystal engineering has important applications in a number of other fields, quite notably in the design of metal‐organic frameworks. Chapters 2 and 3 of this dissertation focus on applying crystal engineering to the synthesis of acene derivatives for use as solid‐state, long‐wavelength fluorescent organic dyes in the field of biomedical imaging. More specifically, this work studied the synthesis and properties of dioxolane‐functionalized pentacenes and hexacenes. One of these pentacene derivatives has already been demonstrated in biomedical imaging which may lead to improved treatment of tuberculosis. The dioxolane‐functionalized hexacene is still under evaluation for bioimaging applications. Chapters 4 and 5 focus on crystal engineering in relation to organic electronics. Chapter 4 deals with fine‐tuning of crystal packing and demonstrated that small differences in molecular structure can result in significant changes to the solid‐state structure which affects semiconductor properties. Finally, chapter 5 studies the use of singlet fission in photovoltaics and demonstrated that this process does occur in a solar cell incorporating a hexacene derivative. Pentadithiophenes were also synthesized for singlet fission photovoltaics, but they have yet to be studied further.

Control of solid state ordering in conjugated small molecules is paramount to the continued development and implementation of organic materials in electronic devices. However, there exists no reliable method on which to predicatively determine how a change to the molecular structure will impact the solid-state packing. As such, the molecule must be synthesized before its solid-state packing can be definitively evaluated. However, once the packing structure of a material is known there exist both qualitative structure- function relationships derived from the literature, as well as quantitative computational methods that can be employed to suggest if a material will perform well in a given device. This type of bottom-up strategy is used in Chapter 2 to design and synthesize a high performance material for organic field effect transistors. A core molecule is synthesized, and through rigorous optimization of pendant and solubilizing groups a material with exceptional solid-state packing is developed and its performance in an organic field effect transistor is discussed. Chapter 3 discusses the use of conjugated organic molecules in conjunction with inorganic materials to develop hybrid organic/inorganic materials. A scalable synthesis is developed so derivatives can be rapidly synthesized and their properties evaluated. Two classes of materials are developed and synthesized: tetracene-based ligands for quantum dots and diammonium-substituted anthracene and tetracene derivatives for 2D-perovskites. Initial results for both classes of materials are presented. Chapter 4 discusses the topochemical photopolymerization of heptacene [4+4] dimers. Multiple derivatives were synthesized in order to give the ideal alignment of molecules in the crystal, followed by irradiation of crystals to give crystal templated polymerization. In Chapter 5, triarylmethane derivatives are synthesized and their performance as radiochromic sensors is evaluated. Chapter 6 involves the development of a robust synthetic scheme toward a difficult to attain π- extended regioisomer of pyrene. Photophysical characterization reveals that the direction of π-extension from the pyrene core has a profound effect on electron delocalization.

Nous étudions les acènes avec le modèle de fonction d'onde électronique fortement corrélé Jastrow antisymmetrized geminal power (JAGP) par Monte Carlo quantique (QMC). Ces méthodes permettent d'optimiser les fonctions JAGP de façon variationnelle (minimisation énergétique), et d'accéder à l'énergie de leur niveau fondamental électronique si les nœuds de leur fonction d'onde sont bien définis. En modulant la liberté variationnelle des formes JAGP nous étudions leurs propriétés électroniques en fonction de la qualité de la fonction d'onde. Nous obtenons ainsi des résultats en faveur d'un caractère fortement résonant mais étalé sur plusieurs états, incompatible avec la présence précédemment supposée de couches ouvertes, et le constat de biais induits par un niveau trop faible de liberté variationnelle. Par relaxation structurale effectuée en QMC sur des fonctions de différentes qualité nous montrons que les géométries des acènes sont très couplées à la structure électronique. Nous pouvons envisager d'étendre cette étude aux hydrocarbures polycycliques aromatiques à l'allure de nanorubans de graphène d'épaisseur croissante afin d'étudier de possible corrélations entre sextets de Clar et l'évolution de leurs propriétés électroniques et spintroniques. / We study the family of acenes by means of quantum Monte Carlo methods (QMC) based on a Jastrow correlated antisymmetrized geminal power (JAGP) wave function. Those methods allows for JAGP optimization in a variational manner (energy minimisation) and for ground state energy evaluations when the wave function nodes are well defined. By tuning the variational freedom of JAGP wave functions we study their electronic properties as a function of the wave function quality. We thus obtain results in favour of a highly resonating character, but smeared on many states, incompatible with a previously supposed open shell character. The study also demonstrates that a too low variational freedom induces high bias in the electronic description. By QMC structural relaxation on wave functions of various quality we demonstrate that the acenes geometry is highly coupled to their electronic structure.We can consider extending this study to general polycyclic aromatic hydrocarbons similar to graphene nanoribbons of growing thickness to investigate possible correlations between Clar sextets et their electronic and spintronic properties.