Study of the Photophysical Properties and the DNA Binding of Enantiopure [Cr(TMP)2(dppn)]3+ Complex

Daniel Graczyk, Rory A. Cowin, Dimitri Chekulaev, Maisie Haigh, Paul Scattergood, Susan Quinn

Research output: Contribution to journalArticlepeer-review

Abstract

The preparation, electrochemistry and photophysical properties of a heteroleptic chromium(III) polypyridyl complex rac-[Cr(TMP)2(dppn)]3+ (1) containing two 3,4,7,8-tetramethyl-1,10-phenanthroline (TMP) ligands and the π-extended benzodipyrido[3,2-a:2′,3′-c]phenazine (dppn) ligand are reported. The visible absorption spectrum of 1 reveals distinct bands between 320 and 420 nm characteristic of dppn-based ligand-centered transitions, with 1 found to be non-emissive in aqueous solution but weakly luminescent in aerated acetonitrile solution. Transient visible absorption (TrA) spectroscopy reveals that 400 nm excitation of 1 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 (3IL) state which persists for longer than 7 ns and efficiently sensitizes singlet oxygen. Chiral resolution and DNA binding of the lambda and delta enantiomers of 1 to four different DNA systems is reported. In all cases the lambda enantiomer shows greater affinity for DNA and in particular AT-rich DNA. Thermal denaturation reveals that the lambda enantiomer stabilizes the DNA more. There is also a greater stabilization of the AT-containing DNA sequences compared to GC DNA.
Original languageEnglish
JournalInorganic Chemistry
Publication statusAccepted/In press - 18 Nov 2024

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