Isophorone- and pyran-containing NLO-chromophores: a comparative study

A series of merocyanines containingisophorone or pyran rings in the spacer have been synthesized. For a given pair of donor and acceptor groups, the isophorone derivatives show higher second-order optical nonlinearities, but lower thermal stabilities. The first NLO-chromophores endowed with a dihydropyran fragment in the spacer have also been prepared and studied.Financial support from MICINN-FEDER (CTQ2008-02942 and MAT2008-06522C02-02) and Gobierno de Aragón-Fondo Social Europeo (E39) is gratefully acknowledged. Predoctoral fellowships to E.G. (CSIC, JAE 2008), N.M.de B. (Departamento de Educación, Gobierno de Navarra) and R. Alicante (FPI BES 2006-12104) are also acknowledged.Peer Reviewe