Solvent effects on the photophysical properties of poly[1,4-dihydroxyanthraquinoneimine-1,3-bis(phenylene-ester-methylene)tetramethyldisiloxane

Abstract

Absorption and fluorescence spectra of a polyquinoneimine, PQI, built on 1,4-dihydroxyanthraquinone and a siloxane diamine, 1,3-bis(amino-phenylene-ester-methylene)tetramethyldisiloxane, have been investigated in solvents of different polarities. The effect of solvents on the spectral properties was investigated using Lippert–Mataga and Bakhshiev polarity functions and Catalán’s multiple linear regression approach. Absorption and fluorescence spectra in studied solvents exhibit hypsochromic and bathochromic shifts, respectively. The polarity of the solvent was the main parameter which changes the spectral properties of PQI. Also, the binary mixtures of chloroform with methanol and dimethyl sulfoxide were used to analyze the intermolecular interactions and preferential solvation. The preferential solvation parameters (local mole fraction (X2L), excess function (δs2) and preferential solvation constant (KPS)) were calculated from spectral data and discussed as a function of cosolvent content. The values of quantum yield, decreased linearly with increasing solvent polarity (for non-polar and polar solvents).