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

A supramolecular assembly, composed of magnesium complex of hypocrellin A (Mg2+ -HA) and pristine C-60 with a molar ratio of 2 : 1, is constructed and characterized. The supramolecular assembly (Mg2+ -HA/C-60) 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(-center dot) radical), followed by electron transfer from the Mg2+ -HA(-center dot) radical to C-60, forming the corresponding anion radical C-60(-center dot) under anaerobic conditions. In aerobic media, the generation of reactive oxygen species, including superoxide anion radical (O-2(-center dot)) and singlet oxygen (O-1(2)), by Mg2+ -HA/C-60 photosensitization is observed. Mg2+ -HA/C-60 exhibits much stronger photodamage ability on pBR322 plasma DNA than Mg2+ -HA and HA under both aerobic and anaerobic conditions.