Synthesis and photophysical properties of new pyrazolines with triphenyl and ester derivatives

New (4S*,5S*)-Methyl 3-(2,3-dimethoxyphenyl)-5-(3,4-dimethoxyphenyl)-1-phenyl-4,5-dihydro-1H-pyrazole-4-carboxylate (4) and its isomer 5 were synthesized from 1,3-dipolar cycloaddition reaction of a hydrazonyl chloride with a cinnamic acid derivative and solvent effects on absorption and fluorescence properties of the novel synthesized pyrazoline derivatives (isomers 4 and 5) were studied by UV-Vis. absorption and steady-state fluorescence spectroscopy techniques. The absorption and fluorescence spectra for both isomers showed that solvent structure and polarity have effect on photophsical properties of the isomer molecules. Isomers 4 and 5 exhibited positive solvatochromism behavior when the polarity of the solvent was increased from p-Xylene to MeOH. Furthermore, isomers 4 and 5 showed very high quantum yields in the solvents except for polar solvents and bromobenzene. Solute-solvent interactions were analyzed by using the solvent polarity parameter (E-T(30)) approach, Lippert-Mataga equation, Kamlet-Taft and Catalan multiple linear regression analysis. These results revealed that the most contributing factor of solute-solvents interactions for the isomer 4 was the solvent acidity whereas the most contributing factors for isomer 5 was the solvent acidity as well as the solvent polarity. (C) 2020 Elsevier B.V. All rights reserved.