Mainz, Universiẗat, Diss., 2000.

CCSD(T) has been used in the past to accurately predict compute the spectra and structures of small molecules. However, the large execution times required for these calculations has limited their use in larger molecules such as benzene and [10]annulene. The parallelization of analytic second derivatives of post Hartree-Fock methods, including CCSD(T), has enabled the VPT2+D treatment of the vibrational states of benzene. The fundamental frequencies and infrared active two quantum transitions that result are within 20 cm⁻¹ of the experimental values when treated for Fermi and Darling-Dennison resonances and empirical estimates for the harmonic frequencies and equilibrium bond lengths are determined to be within 12 cm⁻¹ and 0.004 Å of the values at the CCSD(T)/ANO2(fc) level of theory. The parallelization also facilitated the identification of two candidates for the structures of two isomers of [10]annulene. The harmonic frequencies of several conformations proposed in the literature were computed at the CCSD/DZP level of theory with five of the conformations being ground states. The NMR shifts of four of these structures were computed using CCSD(T)/tzp and conformation 6(C₂ "twist") was identified as the likeliest structure for one of the isomers isolated. The remaining compound was identified as conformation 2b(C₂ "boat") due to a low conformation barrier and the proximity of its average NMR shifts to experiment. The identification of both compounds rely on properties computed using analytic derivatives not entirely on the relative energies of optimized geometries. / text

xxi, 294 p. ill. (some col.) A print copy of this title is available through the UO Libraries under the call number: SCIENCE QD403.O23 2008 / Highly conjugated carbon-rich systems have demonstrated many attractive applications for fundamental and materials science applications, including--but not limited to--probes for aromaticity, charge-transfer complexes, conducting/semi-conducting materials, linear/nonlinear optical materials, and solar cells. The bulk of this research has focused on carbon-rich fullerenes, conjugated polymers, or polycyclic aromatic hydrocarbons; however, with recent developments in cross-coupling chemistry, carbon rich chemistry, particularly dehydrobenzo[ n ]annulenes (DBAs), has grown to yield molecules of great diversity and utility. Concurrently, materials based on conjugated heterocycles have been developed and display similar and often enhanced properties to the aforementioned carbon rich systems. The lone pair of the heterocycle often adds additional stability and polarizablity, creating novel and tunable molecules. Assimilating techniques used to produce DBAs with heteroaromatic molecules, our work has afforded a novel class of conjugated macrocycles with the highly tunable optical-electronic properties of a DBA system. That in turn has led to the systematic study of the diverse structure-property relationships of the thiophene/DBA hybrids reported herein. Chapter I details the synthetic advances in the field of DBA chemistry. The first section discusses the methods of synthesis, inter- vs. intra- molecular approaches, while the remaining sections provide current examples of the DBAs reported. Chapter II briefly discuses conjugated thiophene chemistry, then describes the advantages of utilizing planarized thiophenes. Several examples of thiophene macrocycles are reviewed: both planar and nonplanar. Particular attention in the review focuses on synthesis, optical properties, and some redox properties. Chapters III and IV detail the synthesis and analysis of thiophenes locked into [14]- and [15]annulene scaffolds, respectively. The dehydrothieno[14]annulenes (DTAs) and DTA/DBA hybrids of chapter III serve as aromatic probes and show significant tunabilty with respect to the number and orientation of the thiophenes. Chapter IV's dehydrobenzo[15]annulenes, which are comprised of a cross-conjugated system, also display a structure-property relationship where the optical properties encompass a wider dispersion of wavelengths. Chapter IV also explores the incorporation of pyridines and the affects on conjugation. The electronic properties of the macrocycles were explored using NMR, UV-Vis absorption and fluorescence spectroscopy, and electrochemically (cyclic voltammetry). Chapter V is devoted to further functionalization of DTAs through alkylation and further cycliziation to yield planarized terthiophene units. This dissertation includes my previously published and co-authored material. / Adviser: Michael M. Haley

No description available.

Darmstadt, Techn. Univ., Diss., 2001.

Techn. Univ., Diss., 2001--Darmstadt

No description available.

No description available.

xx, 318 p. ： ill. (some col.) / Highly conjugated, carbon rich molecules are of great interest due to their unique optoelectronic properties. These molecules are now recognized as suitable materials for advanced materials applications such as light-emitting diodes, photovoltaics, and thin film transistors. Of particular interest is the indenofluorene (IF) scaffold, a 6-5-6-5-6-fused ring system that holds a striking topological similarity to pentacene, a very successful electron donating organic semiconductor. Also of interest is another class of compounds referred to as tetrakis(arylethynyl)benzenes, TAEBs, which are cruciform-shaped molecules that possess numerous pathways for electronic and photonic transfer and are amenable to a host of substitution patterns. Chapter I examines the history of the IF scaffold and its development over the last century through the use of literature examples relating to both its synthesis and potential use as an emerging class of electron accepting materials. Chapter II introduces the feasibility of stable, fully conjugated IFs. Two examples of 5,6,11,12-tetraethynyl-indeno[1,2- b ]fluorenes are synthesized where their structural and optoelectronic properties are explored. Chapter III further explores the IF scaffold and outlines the synthesis of a series of 6,12-diethynylindeno[1,2-b ]fluorenes in conjunction with detailed computational, structural, and photophysical studies. Chapter IV discusses the synthesis and characterization of a series of 6,12-diarylindeno[1,2- b ]fluorenes and examines their structural and optoelectronic properties. Chapter V describes a series of donor/acceptor-functionalized TAEBs that incorporate the 4,4-difluoro-4-bora-3a,4a,-diaza-s -indacene moiety, better known as BODIPY, as the acceptor unit. Additionally, two TAEB molecules and three structurally related bis(arylethynyl)benzene (BAEB) isomers where only acceptors are used to evaluate the effectiveness of the donor group are synthesized. This dissertation includes both previously published and unpublished co-authored material. / Committee in charge: Professor David R. Tyler， Chairperson； Professor Michael M. Haley， Advisor； Professor Victoria J. DeRose， Member； Professor Shih-Yuan Liu， Member； Professor Scott D. Bridgham， Outside Member