Study of the Photophysical Properties and the DNA Binding of Enantiopure [Cr(TMP)(dppn)] Complex.

The preparation, electrochemistry and photophysical properties of a heteroleptic chromium(III) polypyridyl complex [Cr(TMP)(dppn)] () containing two 3,4,7,8-tetramethyl-1,10-phenanthroline (TMP) ligands and the π-extended benzodipyrido[3,2-a:2',3'-]phenazine (dppn) ligand are reported. The visible absorption spectrum of reveals distinct bands between 320 and 420 nm characteristic of dppn-based ligand-centered transitions, with found to be nonemissive in aqueous solution but weakly luminescent in aerated acetonitrile solution. Transient visible absorption (TrA) spectroscopy reveals that 400 nm excitation of leads to initial population of a ligand-to-metal charge transfer (LMCT) state which evolves within tens of ps to form a dppn-localized intraligand (IL) state which persists for longer than 7 ns and efficiently sensitizes singlet oxygen.