Iridium and ruthenium complexes covalently bonded to carbon surfaces by means of electrochemical oxidation of aromatic amines

Bis(2-phenylpyridinate-C2,N)-(4-(4-aminophenyl)-2,2'-bipyridine) iridium(III) hexafluorophosphate and bis(2,2'-bipyridine-N,N')-(4-(4-aminophenyl)-2,2'-bipyridine) ruthenium(II) hexafluorophosphate were synthesized and characterized. In particular, electrochemical analyses showed irreversible amine-centred oxidations, which were exploited to functionalize a glassy carbon electrode. The functionalization was achieved by electrochemical oxidation of the amino group. Surface modification was observed and studied via electrochemical techniques (cyclic voltammetry, square wave voltammetry). The functionalization was performed at different potential values, and the effect of the collidine (2,4,6-trimethylpyridine) was evaluated. The surface coverage was assessed by integration of the peak current of the modified electrode signal. The formation of monolayers or multilayers depends on the oxidation potential used and on the presence of collidine in the functionalization cell.