Solvent effect on static and dynamic first hyperpolarizability of azochromophore with tricyanopyrrole acceptor moiety

Abstract

Solvent effect on molecular nonlinear optical (NLO) characteristics of azochromophore with tricyanopyrrole acceptor, AAB-TCP, is estimated within different models: polarizable continuum model (PCM), supermolecule (SM), semicontinuum (SC). The values of first hyperpolarizability are calculated by TD-DFT at M06-2X/aug-cc-pVDZ level; the dynamic characteristics are evaluated at 0.65 eV frequency. Molecular dynamics of AAB-TCP solution in acetone (at concentration 2·10−2 mol%) is performed in amorphous cell what allowed to reveal different types of hydrogen-bonded supermolecules formed by AAB-TCP and one or two acetone molecules; for four supermolecules the first hyperpolarizability values are calculated. Solvent effect accounted within the PCM approach causes almost 4 times increase of static first hyperpolarizability. The account of direct interaction within supermolecule model results in the growth of first hyperpolarizability and describes the solvent effect partly; the estimations at semicontinuum level show further increase (by 40% for static and 50% for dynamic cases) of first hyperpolarizability compared to the PCM values, thus demonstrating the role of solute-solvent hydrogen bonding.