Spectroscopic Studies on the Interaction of Au(II1) with Nucleosides, Nucleotides, and Dimethyl Phosphate

A series of complexes of Au(II1) with nucleosides and nucleotides and their methyl deriv-atives in different stoichiometry have been prepared. Ultraviolet, visible, ir, and nmr studies have been performed to determine the site of binding of these ligands with the metal ion. In (1:4) Au(II1): guanosine complex, N7 is the binding site, whereas a t 1:l complex, a bidentate type of chelation through C6O and N7 is observed. Cs-NH2 is favored over N1 as coordinating site a t all stoichiometry in the adenosine complex. Inosine binds through N1 a t r = 1. In cytidine, N1 is the binding site, whereas thymidine reacts only a t high pH. In the case of nucleotides a bidentate type of chelation through the phosphate and the ring nitrogen occurs. The phosphate binding ability of Au(II1) was further confirmed by studying the interaction of Au(II1) with dimethyl phosphate-a conformational analog of the phosphate backbone in DNA chain