Solvent-dependent photophysical and photochemical properties of genistein: Insights from spectroscopic and quantum chemical analysis

Abstract

Experimental (steady-state absorption and fluorescence techniques) and quantum chemistry (density functional theory (DFT) calculations) methods have been used in order to investigate the solvent-dependent photophysical and photochemical properties of genistein (GEN) – isoflavone with potential therapeutic applications, particularly in the treatment of neurodegenerative diseases such as Alzheimer's disease. The effect of microenvironment on spectral behaviour was analyzed in terms of three models: the Reichardt's single parameter polarity scale ($E_N^T$), the linear solvation energy relationship (LSER) developed by Catalán, solvatochromic shift methods based on the Onsager's description of universal solute-solvent interactions. The experimental results, supported by quantum chemical calculations, indicate that both non-specific and specific (hydrogen bond) interactions contribute to the observed solvatochromism. Since a general understanding of the effect of microenvironment on the GEN solvatochromism cannot be achieved without determining the values  of the dipole moment in the ground (${\overrightarrow{\mu }}_g$) and excited (${\overrightarrow{\mu }}_e$) states, these important physical parameters were obtained using solvatochromic shift methods and quantum chemical calculations. Additionally, the role of solute polarizability on the obtained dipole moment values is also addressed. In the light of our studies, it can be concluded that understanding the molecular mechanisms underlying GEN-microenvironment interactions is of great importance considering its therapeutic applications.