Investigation of the Spectral Properties of Noncovalent Complexes of a Polysubstituted Water-Soluble Derivative of the C60 Fullerene and Chlorin e6 in Polar Solvents

Abstract

Using methods of absorption and fluorescence spectroscopy, we show that noncovalent complexes based on a water-soluble fullerene derivative and chlorin e6 dissolved either in water or in ethanol are formed as a result of electrostatic interactions. The formation of these complexes causes a red shift of the absorption spectrum of chlorin e6 and efficient quenching of the intensity of its fluorescence. The Stern–Volmer quenching constants of complexes in water and ethanol are 7.3 × 10⁵ and 2 × 10⁵ M^–1, respectively. We show that, in an aqueous solution, the complex consists, on average, of one molecule of the water-soluble fullerene derivative and three dye molecules, whereas this ratio in ethanol is 1 : 1.