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2 Polish Journal of Chemistry

2 2002

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Relationship Between Electronic structure and Nonlinear Optical Activity of Push-Pull Polyenes: Step Towards a Quantitative Treatment

Zuev M., Nefediev S. E., Bredas J. -L.

Polish Journal of Chemistry

2002

Vol. 76 / nr 9

1211-1222

Mesomeric effect of substituents in stereoregular push-pull polyenes has been studied, bond length alternation being used for the monitoring of _-electron displacement along the polyene segment. Quantitative calibration of the _-donor and _-acceptor strength of various substituents has been performed with the special scale of substituents mesomeric constants. A simple quantum chemical technique for estimation of mesomeric constants has been developed. A simple additive equation describing the substituents mesomeric effect on bond length alternation in push-pull polyenes has been elaborated. Specific push-pull effect has been demonstrated to be the essential feature of push-pull polyenes. A qualitative relationship between the suggested mesomeric constants and longitudinal hyperpolarizability has been established.

Quantum-Chemical Calculations of First-Order Hyperpolarizability of Epoxy Oligomers with Chromophore in the main Chain

Balakina M., Ilyazov M. F., Zuev M. B.

Polish Journal of Chemistry

2002

Vol. 76 / nr 9

1199-1209

Results of quantum-chemical calculations of first hyperpolarizabilities for a number of epoxy oligomers with nonlinear optical (NLO) chromophores incorporated into the main chain as a side group are presented. These oligomers simulate the internode chains of cross-linked NLO materials, which are the most promising candidates for application in optoelectronics. The attempt is made to establish a relationship between the hyperpolarizability and the conformation of the bearing chain in the vicinity of the chromophore. The structure and conformation of the oligomer chain are shown to affect significantly the longitudinal hyperpolarizability of the chromophore. Some recommendations are given to obtain hyperpolarizability values optimal for the studied molecular systems.