Dual photoreactivity of a new Rh-2(II,II) complex for biological applications

作者：Akhimie Regina N; White Jessica K; Turro Claudia

来源：Inorganica Chimica Acta, 2017, 454: 149-154.

DOI：10.1016/j.ica.2016.04.001

• Rhodium
• Photochemistry
• DNA binding
• Ligand dissociation
• Singlet oxygen
• Dual activity

A new Rh-2(II,II) complex containing one dppn (benzo[i]dipyrido[3,2-a:2',3'-h]quinoxaline) ligand with an extended pi-system, cis-H,H-[Rh-2(OCCH3NH)(2)(dppn)(CH3CN)(2)](2+) (2), was synthesized and characterized. The dppn ligand, which serves as a DNA intercalator, chelates to a single Rh center and is positioned trans to the amidato N atoms of the bridging acetamide ligand. This ligand also possesses a low-lying, dppn-centered (3)pi pi* state that is advantageous for the sensitization of singlet oxygen (O-1(2)), which complex 2 produced with a quantum yield, Phi(460)(1O2) 0.22(7) with 460 nm excitation. In addition, one equivalent of CH3CN is released from 2 upon irradiation with visible light, generating cis-H,H-[Rh-2(OCCH3NH)(2)(dppn)(H2O) (CH3CN)](2+) in aqueous media with photoinduced ligand exchange quantum yield, Phi(450)(LE) or,of 0.0033(1). Thermal denaturation and relative viscosity studies are consistent with a pi-stacking interaction of 2 with double-stranded DNA together with covalent binding to the duplex upon irradiation with visible light. Therefore, 2 exhibits dual photoreactivity toward DNA, making it potentially useful for photochemotherapy with enhanced activity relative to compounds able to achieve only one mode of cell death upon irradiation.

• 出版日期2017-1-1