This collaborative award, made under the Materials Chemistry and Chemical Processing Initiative, is supported by the Divisions of Chemistry and Materials Research. The theme of the research is the development of structure-property relationships for optimizing second-order nonlinear optical properties of organic materials. The goal is to develop and implement synthetic strategies, guided by theoretical studies, which will optimize molecular hyperpolarizability by tuning the degree of bond alternation in the pi-electron system between donor and acceptor. A novel theoretical method will be used to calculate the effective anharmonic potential surfaces associated with the nonlinear optical chromophores. Spectroscopic studies will provide a quantitative measure of bond alternation. These measurements, correlated with measurements of hyperpolarizability, will provide the basis for synthesizing optimized structures. New optimized materials will make feasible fast, low-power, high-contrast electrooptic switching elements. %%% Materials with large second order nonlinearities are desired in applications such as telecommunications, optical data storage, and optical information processing.