Nonlinear optical chromophores containing dithienothiophene as a new type of electron relay

Nonlinear optical (NLO) donor-acceptor (D-A) chromophores containing a fuse d terthiophene, namely dithienothiophene (DTT) as electron relay, and vario us strength acceptors were synthesized to evaluate the relay's role in the solvatochromism as well as in the molecular nonlinearity, mu beta(0). Their solvatochromic behavior, which is dependent on acceptor strength, is corre lated to their mu beta(0). The static quadratic hyperpolarizability, beta(0 ), of DTT-containing chromophores was determined by EFISH measurements. Fro m the comparison of mu beta(0) values of D-A chromophores based on oligothi ophenes, it was assessed that DTT as relay is significantly more efficient compared to bithiophene (the same number of conjugated double bonds) and te rthiophene. An additional merit of DTT is that chromophores containing DTT have a noticeably high thermal stability.