Synthesis, characterization, and optical properties of 4 H-pyran-4-ylidene donor-based chromophores: The relevance of the location of a thiophene ring in the spacer

A series of new 4H-pyran-4-ylidene donor-based chromophores with a thiophene ring in the spacer has been synthesized. The linear and nonlinear optical (NLO) properties of these compounds have been determined and compared with the results of computational calculations. The position of the thiophene ring proved essential to optimize the figure of merit μβ, with the best results obtained when the heterocyclic system was closer to the donor moiety. © 2012 American Chemical Society.We thank the Spanish Ministry of Science and Innovation, MICINN-FEDER (Projects CTQ2008-02942, CTQ2011-22727, MAT2008-06522-C02-02, and MAT-2011-27978-C02-02) and the Gobierno de Aragón-Fondo Social Europeo (E39) for financial support. N.M.d.B. thanks the Departamento Educación, Gobierno de Navarra, for a predoctoral grant.Peer Reviewe