Preparation and electrochemical behaviour of {[Ru(bipy)4Cl2Ag]NO3(CHCl3)·6H2O}n obtained from the self-assembly of trans-Ru(bipy)4Cl2 and AgNO3

The synthesis and characterization of Ru(II) and Ru(II)-Ag(I) compounds are described, in view of their potential use in on/off switchable metal-ridge-metal nanodevices. The compound trans-Ru(bipy)₄Cl₂ (1) [bipy, 4,4′-bipyridine] has been prepared by Ru(DMSO)₄Cl₂ (2) (DMSO, dimethylsufoxide) and an excess of bipy. The compound has been fully characterised by physico-chemical, spectroscopic and single crystal X-ray determinations. trans-Ru(bipy)₄Cl₂ has been employed as building block in a self-assembly reaction with AgNO₃ obtaining the inorganic polymer {[Ru(bipy)₄Cl₂Ag]NO₃ (CHCl₃)·6H₂O}_n (3). The self-assembled Ru-Ag compound has been investigated by infrared (IR), ultraviolet (UV) and visible (vis) spectroscopy, elemental analyses, inductively coupled plasma optical emission spectroscopy (ICP-OES) and thermogravimetric analysis coupled with infrared detector (TGA-IR). The electrochemical behaviour of 1 and 3 have been studied by means of cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). 1 and 3 have been tested both as soluble species in non-aqueous solvents and as self-assembled molecules on gold electrodes in aqueous medium. The electrochemical behaviour of the parent compounds trans-Ru(pyz)₄Cl₂ (4) [pyz, pyrazine] and {[Ru(pyz)₄Cl₂Ag]NO₃}_n (5) have been also investigated for comparison.