Solvent effect on the UV/Vis absorption and fluorescence spectroscopic properties of berberine

Abstract

Spectral and photophysical properties of the alkaloid berberine (B) were studied in solvents with different solvent parameters, using UV/Vis absorption, emission and excitation spectroscopy. The absorption and emission maxima were found to be between 421–431 nm and 514–555 nm, respectively, leading to Stokes’ shifts between 4099 and 5735 cm⁻¹. The fluorescence quantum yields varied between 10⁻²–10⁻⁴, depending on the solvent. Different solvent scales have been used to study the solvatochromism of B. Linear solvation energy relationships (LSER) proposed by Kamlet–Taft suggest that B is a molecule attractive as a probe for solvent polarity and hydrogen bonding properties.