Theoretical studies on DNA-photocleavage efficiencies of Ru(II) polypyridyl complexes

Theoretical studies on the DNA-photocleavage efficiencies of Ru(II) polypyridyl complexes 1-4 have been carried out using density functional theory (DFT). First, an evaluation of the computational accuracy of the redox potentials for [Ru(bpy)(3)](2+) in the ground state and the excited state was tested by different computational methods. Secondly, the redox potentials of complexes 1-4 in the excited state were accurately computed. Finally, the trend in the DNA-photocleavage efficiencies (φ) of complexes 1-4, i.e., φ(4) > φ(3) > φ(2) > φ(1), were reasonably explained by the excited-state reduction potentials and the electron-transfer activation energies. In particular, the DNA-photocleavage efficiencies of two new Ru(II) complexes 3 and 4 were predicted.