Organometallic Ruthenium Nitrosyl Obtained by C-H Bond Activation - Photoinduced Delivery of Nitric Oxide and NO-Mediated Antiproliferation Activity Studies

The azo dye methyl red, which has carboxylato and azo functional groups, was used as a ligand for the synthesis of the cyclometalated Ru-III complex [Ru(L-1)(PPh3)(2)Cl] (1, (LH2)-H-1 = 2-{[4-(dimethylamino)phenyl]diazenyl}benzoic acid) through C-H bond activation. Complex 1 was treated with nitric oxide to afford the organometallic ruthenium nitrosyl complex [Ru((LH)-H-2)(PPh3)(2)(NO)Cl][ClO4] (1a, (LH)-H-2 = 2-{[4-(dimethylamino)-3-nitrophenyl]diazenyl}benzoic acid). The molecular structures of 1CH(3)OH and 1aCH(3)OH were determined by X-ray crystallography. The diamagnetic complex 1a with S = 0 ground state was studied by H-1 and P-31 NMR spectroscopy. In the nitrosyl complex, the coordinated NO is photolabile under UV and visible light, and the liberated NO was trapped by reduced myoglobin. The NO, photoreleased under visible light, was utilized in antiproliferation activity studies on human (A549, HEK293T, and HeLa) and mouse (NIH3T3) cancer cell lines.