Effect of solvent polarity on the photophysical properties of chalcone derivatives

The absorption and fluorescence characteristics of (E)-3-(furan-2-yl)-1-(4-nitrophenyl)prop-2-en-1-one (FNPO), (E)-1-(4-aminophenyl)-3-(furan-2-yl)prop-2-en-1-one (AFPO) and (E)-3-(furan-2-yl)-1-(2-hydroxyphenyl)prop-2-en-1-one (FHPO) were recorded in eighteen different solvents with increasing polarities at room temperature. The solvatochromic effects on absorption and fluorescence spectra have shown bathochromic shifts from non-polar to polar solvents for the reported molecules due to intramolecular charge transfer (ICT) interactions. It has indicated a large difference in dipole moment between electronically ground and excited states and the molecules were found to be more stabilized in singlet excited state than the ground state. The ground and excited state dipole moments of FNPO, AFPO and FHPO were determined experimentally by solvatochromic shift method using Bilot-Kawski, Lippert-Mataga, Bakhshiev, Kawski-Chamma-Viallet and Reichardt's microscopic solvent polarity functions. HOMO-LUMO energy values of FNPO, AFPO and FHPO were determined using cyclic voltammetry and compared with those values obtained by TD-DFT (B3LYP/6-311G(d,p)) method.