Push–pull chromophores incorporated in 1,3-dithiol-2-ylidene moiety as new electrooptics materials

Experimental and theoretical investigations of influence of the push–pull chromophores incorporated in the 1,3-dithiol-2-ylidene moiety as the electron donating part on linear electrooptic (Pockels) coefficient have been performed. The proposed theoretical approach is based on geometry optimization of the molecule and appropriate quantum chemical calculations. Intermolecular interactions are evaluated within a framework of long-range intermolecular interactions. Based on approach combining local density approximation (LDA) and Hartree–Fock method we have revealed good correlation between the experimental and theoretical values of linear electrooptical coefficients (EOC). Contribution of electronic UV and phonon modes to EOC tensor component r111 (λ=633 nm) was evaluated. The phonon and UV modes have been found to be very sensible to substitution of the chromophores. Analysis of contributions of particular molecular group is done.