Photodynamic properties of supramolecular assembly constructed by magnesium complex of hypocrellin A and fullerene C60

Abstract

A supramolecular assembly, composed of magnesium complex of hypocrellin A (Mg²⁺–HA) and pristine C₆₀ with a molar ratio of 2 : 1, is constructed and characterized. The supramolecular assembly (Mg²⁺–HA/C₆₀) shows moderate solubility in polar solvents and strong absorption in visible region. EPR studies demonstrate that one-electron transfer from N,N-diethylaniline (DEA) to excited-state Mg²⁺–HA induces the generation of the reduced form of Mg²⁺–HA (Mg²⁺–HA⁻˙ radical), followed by electron transfer from the Mg²⁺–HA⁻˙ radical to C₆₀, forming the corresponding anion radical C₆₀⁻˙ under anaerobic conditions. In aerobic media, the generation of reactive oxygen species, including superoxide anion radical (O₂⁻˙) and singlet oxygen (¹O₂), by Mg²⁺–HA/C₆₀ photosensitization is observed. Mg²⁺–HA/C₆₀ exhibits much stronger photodamage ability on pBR322 plasma DNA than Mg²⁺–HA and HA under both aerobic and anaerobic conditions.