Nonlinear optical (NLO) donor-acceptor (DA) chromophores containing a fused terthiophene, namely dithienothiophene (DTT) as electron relay, and various strength acceptors were synthesized to evaluate the relay's role in the solvatochromism as well as in the molecular nonlinearity, µβ (0). Their solvatochromic behavior, which is dependent on acceptor strength, is correlated to their µβ (0). The static quadratic hyperpolarizability, β (0) ...