SOLVENT EFFECTS ON LINEAR AND NONLINEAR-OPTICAL PROPERTIES OF DONOR-ACCEPTOR POLYENES - INVESTIGATION OF ELECTRONIC AND VIBRATIONAL COMPONENTS IN TERMS OF STRUCTURE AND CHARGE-DISTRIBUTION CHANGES
R. Cammi et al., SOLVENT EFFECTS ON LINEAR AND NONLINEAR-OPTICAL PROPERTIES OF DONOR-ACCEPTOR POLYENES - INVESTIGATION OF ELECTRONIC AND VIBRATIONAL COMPONENTS IN TERMS OF STRUCTURE AND CHARGE-DISTRIBUTION CHANGES, Journal of the American Chemical Society, 120(34), 1998, pp. 8834-8847
We investigate the influence of solvation media upon the relationship
among structure, spatial distribution of electron density, and linear
and nonlinear electric properties for two series of push-pull pi-conju
gated molecules. The analysis is performed on both electronic and vibr
ational components of static polarizability and first hyperpolarizabil
ity, and the effects solvent induce on them are analyzed singularly wi
thin the framework of the polarization continuum model. Solvent is fou
nd to affect the extent of charge separation induced in the ground sta
te of these molecules. This charge separation leads to a geometric dis
tortion, measured by the bond-length-alternation (BLA) parameter, whic
h shows a solvent-induced evolution of the molecular geometry from a n
eutral, bond-alternated polyene-like structure, to a partially ionic c
yanine-like structure, and ultimately to an ionic bond-alternated stru
cture. As a consequence large changes in the linear and nonlinear resp
onse properties are found, in both their electronic and vibrational co
ntributions. Regarding the latter, we recall that studies on vibration
al (hyper)polarizabilities for molecular systems in solution are prese
nted here for the first time.