Effect of cytosine–Ag+–cytosine base pairing on the redox potential of the Ag+/Ag couple and the chemical reduction of Ag+ to Ag by tetrathiafulvalene

Abstract

The redox properties of metallo-base pairs remain to be elucidated. Herein, we report the detailed ¹H/¹³C/¹⁰⁹Ag NMR spectroscopic and cyclic voltammetric characterisation of the [Ag(cytidine)₂]⁺ complex as isolated cytosine–Ag⁺–cytosine (C–Ag⁺–C) base pairs. We also performed comparative studies between cytidine/Ag⁺ and other nucleoside/Ag⁺ systems by using cyclic voltammetry measurements. In addition, to evaluate the effect of [Ag(cytidine)₂]⁺ formation on the chemical reduction of Ag⁺ to Ag, we utilised the redox reaction between Ag⁺ and tetrathiafulvalene (TTF). We found that Ag⁺-mediated base pairing lowers the redox potential of the Ag⁺/Ag couple. In addition, C–Ag⁺–C base pairing makes it more difficult to reduce captured Ag⁺ ions than in other nucleoside/Ag⁺ systems. Remarkably, the cytidine/Ag⁺ system can be utilised to control the redox potential of the Ag⁺/Ag couple in DMSO. This feature of the cytidine/Ag⁺ system may be exploited for Ag nanoparticle synthesis by using the redox reaction between Ag⁺ and TTF.