Formation of Mixed-Ligand Complexes of Pd2+ with Nucleoside 5-Monophosphates and Some Metal-Ion-Binding Nucleoside Surrogates

摘要

Formation of mixed-ligand Pd²⁺ complexes between canonical nucleoside 5'-monophosphates and five metal-ion-binding nucleoside analogs has been studied by ¹H-NMR spectroscopy to test the ability of these nucleoside surrogates to discriminate between unmodified nucleobases by Pd²⁺-mediated base pairing. The nucleoside analogs studied included 2,6-bis(3,5-dimethylpyrazol-1-yl)-, 2,6-bis(1-methylhydrazinyl)- and 6-(3,5-dimethylpyrazol-1-yl)-substituted 9-(β-d-ribofuranosyl)purines >1–>3, and 2,4-bis(3,5-dimethylpyrazol-1-yl)- and 2,4-bis(1-methylhydrazinyl)-substituted 5-(β-d-ribofuranosyl)-pyrimidines >4–>5. Among these, the purine derivatives >1->3 bound Pd²⁺ much more tightly than the pyrimidine derivatives >4, >5 despite apparently similar structures of the potential coordination sites. Compounds >1 and >2 formed markedly stable mixed-ligand Pd²⁺ complexes with UMP and GMP, UMP binding favored by >1 and GMP by >2. With >3, formation of mixed-ligand complexes was retarded by binding of two molecules of >3 to Pd²⁺.