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Proceedings Paper

Computational chemistry methods for predicting the chiroptical properties of liquid crystal systems: II. Application to chiral azobenzenes
Author(s): Kenneth L. Marshall; Anthony G. Noto; Gallia Painter; Nelson Tabiryan
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Paper Abstract

Advances in computational chemistry hardware and software now make it possible to accurately model and predict physical properties (e.g., electronic spectra and chirality) in terms of hours or days instead of the weeks or months of intensive effort that were required only a few years ago. Previously, we reported on the effectiveness of computational modeling methodology in predicting the helical twisting power (HTP) for both well known chiral dopants and a series of novel nickel dithiolene IR dyes in a liquid crystal host. This earlier work, we showed that that correlation between the computationally derived weighted, scaled-chirality index G0SW and HTP for materials with rigid molecular structures was excellent, but the high dependence of G0SW on conformational energy in flexible molecular systems results in an inadequate representation of the true system conformational energy if only a single computed energy-minimized conformer is used in the calculations. By taking into account additional contributions to G0SW through Monte Carlo simulation of a large number of energy-minimized conformers, a new multiconformer model was developed for flexible molecular systems that showed a 67% improvement in the predictive accuracy for G0SW and HTP for a series of chiral dopants previously evaluated by the single-conformer model. The single-conformer model was also applied successfully to a series of rigid azobenzene molecular systems to accurately predict HTP for both geometric isomeric forms, which to our knowledge, is the first time that any quantitative chirality calculations have been attempted with compounds that exhibit a strong relationship between HTP and geometric isomerism.

Paper Details

Date Published: 15 September 2006
PDF: 10 pages
Proc. SPIE 6332, Liquid Crystals X, 63320C (15 September 2006); doi: 10.1117/12.680080
Show Author Affiliations
Kenneth L. Marshall, Univ. of Rochester (United States)
Anthony G. Noto, Univ. of Rochester (United States)
Gallia Painter, Univ. of Rochester (United States)
Nelson Tabiryan, BEAM Engineering for Advanced Measurements Co. (United States)

Published in SPIE Proceedings Vol. 6332:
Liquid Crystals X
Iam-Choon Khoo, Editor(s)

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