Trinuclear Metal Complexes Based on 1,10-Phenanthroline Derivates as Catalysts for Cleavage of a RNA-Model Substrate

Two multidentate ligands 2,9-di [6′-(2″-hydroxyl-3″-methoxyphenyl) -n-2′,5′-diazahexyl]-1,10-phenanthroline (LA) and 2,9-di(6′-α-phenol-n-2′,5′-diazahexyl)-1,10-phenanthroline(LB) were synthesized and fully characterized. Protonation of the ligands and the stability of the complexes of the ligands with divalent metal ions were investigated. The trinuclear metal complexes [Cu(II) and Zn(II)] of the ligands were studied, as catalysts, for the transphosphorylation of the RNA-model substrate 2-hydroxypropyl-p-nitrophenyl phosphate (HPNP). The second-order rate constants of HPNP-hydrolysis catalyzed by M3 L and M3 LH-1 were obtained, which indicated that Zn3 LBH1- was the most efficient catalyst among them. The proposed mechanisms included the activation of the substrate via binding to the metal ions and intramolecular nucleophilic attack by the deprotonated C2-hydroxyl of HPNP.