Solvatochromic effect on UV-vis absorption and fluorescence emission spectra, second- and third-order nonlinear optical properties of dicyanovinyl-substituted thienylpyrroles: DFT and TDDFT study

Abstract

The nonlinear optical properties of dicyanovinyl-thienylpyrroles 1-6 compounds were investigated by the determining of the first-order molecular static hyperpolarizability (beta) and the second-order molecular static hyperpolarizability (gamma) in the ground state by using the HSEh1PBE/6-311G(d,p) level of density functional theory (DFT). The photophysical behavior of compounds 1 and 5 in polar and non-polar solvents was studied by using UV-vis absorption and fluorescence emission spectroscopies. In order to investigate the effects of these solvents, the time-dependent density functional theory (TD-DET) calculations with the polarizable continuum model (PCM) in the excited state were performed. The UV-Vis absorption and fluorescence emission spectra for compound 5 were also simulated using TD-HSEh1PBE/6-311G(d,p) level, and the major contributions to the electronic transitions for compounds 1-6 were obtained. The beta(0) value (18.74 x 10(-30) esu) calculated by using HSEh1PBE/6-311G (d,p) for compound 2 is 1.49 times lower than the experimental value (28 x 10(-30) esu), and 234 times greater than pNA value (8 x 10(-30) esu). The beta and gamma parameters for compound 2 is lower than 1 and 3-6 due to electron donating pyrrole ring and electron accepting dicyanovinyl group. Moreover, we used the hybrid DFT methods (B3LYP, M062X, CAM-B3LYP and BHandHLYP) to show the accuracy for first static hyperpolarizability values for compounds 1-6. The beta(0) parameter for compound 5 in both polar and non-polar solvents was examined by using two level model. (c) 2016 Elsevier B.V. All rights reserved.