New Photosensitizers Based on Glycosylated Derivatives of Cationic Porphyrins: Optical and Acid–Base Properties and Interaction with Three-Component Anionic Quantum Dots

A comparative study is performed of the acid–base and optical properties of water-soluble porphyrin photosensitizers with meso-(3'-methylpyridyl) and meso-(β-D-galactopyranosyloxy)phenyl substituents. Due to the high hydrophilicity of these meso-substituents, the obtained compounds are quite soluble in water and have a linear concentration dependence of absorption and fluorescence in the working range. It is established that the photosensitizers are diprotonated on a porphyrin platform with close values of step constants, accompanied by a strong rise in the intensity of long-wave absorption, fluorescence, and fluorescence quantum yield. Introducing galactose fragments into the periphery of the macrocycle raises the observed rate of photodecomposition, testifying to the greater efficiency of singlet oxygen generation. It is shown that the studied cationic porphyrin photosensitizers can form effective charge-transfer nanoconjugates with colloidal quantum dots.