Efficient second-order nonlinear optical chromophores based on dithienothiophene and thienothiophene bridges

Two series of push–pull systems bearing dithienothiophene or thienothiophene as (part of) π-conjugated spacer have been synthesized. These compounds combine high second-order molecular nonlinearities with good thermal stabilities, showing one of the thienothiophene (TT) derivative the highest μβ0 value found for a 4H-pyranylidene-containing merocyanine.Financial support from MICINN-FEDER (CTQ2011-22727, and MAT2011-27978-C02-02) and Gobierno de Aragón-Fondo Social Europeo (E39) is gratefully acknowledged. A predoctoral fellowship to A.B.M. (FPI BES-2009-016966) is also acknowledged.Peer Reviewe