Novel functionalized oligo-vinylthiophene molecules with modulated second-order nonlinear optical response

We present a joint theoretical and experimental investigation of the second -order nonlinear optical properties of a new kind of active molecule with a triblock structure. The molecular architecture is such that two highly pol arizable conjugated segments are separated from each other by a spacer; one of the conjugated segments is end-capped with an electron-donor group, the other one by an acceptor. E-vinylthiophenes are used as the conjugated seg ments; N,N-dimethylaniline and nitrophenyl are selected as the donor-accept or pairs, while the spacer consists of a nonconjugated moiety. Several spac ers are considered and discussed with respect to their ability to modulate the charge transfer between the donor and acceptor ends. (C) 2000 Elsevier Science B.V, All rights reserved.