A series of novel donor-acceptor chromophores designed to have good second order nonlinear optical responses has been synthesized and characterized. This series of compounds was designed to explore the consequence of using different electron accepting moieties which were linked through an arylthiophene bridge to a pyrrole heterocycle that plays the role of an auxiliary donor group. These new push-pull chromophores have been extensively characterized using cyclic voltammetry, thermogravimetric analysis and hyper-Rayleigh scattering (HRS) in solution. The measured molecular first hyperpolarizabilities and the observed electrochemical behavior showed that they were very sensitive to the acceptor strength of the acceptor moieties. Moreover, the combination of their good nonlinearity and high thermal stability make them good candidates for potential device applicationsThanks are due to the Fundacao para a Ciencia e Tecnologia (Portugal) and FEDER for financial support through the Centro de Quimica and Centro de Fisica-Universidade do Minho, Project PTDC/QUI/66251/2006 (FCOMP-01-0124-FEDER-007429), Project PTDC/CTM/105597/2008 with funding from COMPETE/FEDER and a research grant to M.C. R. Castro (UMINHO/BI/142/2009). The NMR spectrometer Bruker Avance III 400 is part of the National NMR Network and was purchased within the framework of the National Program for Scientific Re-equipment, contract REDE/1517/RMN/2005 with funds from POCI 2010 (FEDER) and FCT
