Multi-modal surface grafting of [trans-bis(aminodiphenylphosphine) terpyridine-Ru(II)Cl]+Cl− complex onto glassy carbon electrode

Abstract : The design of a ruthenium-terpyridine complex having 4-aminobenzyl-diphenylphosphine as remote ligands in a trans arrangement ([Ru(trans-PN)2(trpy)Cl]+Cl−, [trans-bis(aminodiphenylphosphine) terpyridine-Ru(II)Cl]+Cl−) is shown to be a highly versatile approach for the immobilization of the organometallics at a carbon surface. Three distinct strategies could be then successfully employed to achieve the grafting of the complex, namely i) the electroreduction of the corresponding in situ produced diazonium cation, ii) the electrooxidation of the aromatic amine moiety in the presence of a base and iii) an anodic electropolymerization in the absence of base. The modified surfaces were characterized by electrochemical or Scanning Electron Microscopy (SEM) studies. The reported approach allows a clean modulation of film thickness and anchoring modes, particularly useful for a given design of ruthenium containing films dedicated to a given application. In this context, the polymer films which contain the largest surface concentration of active ruthenium were employed as immobilized catalyst for oxidation of benzyl alcohol in water, allowing a test of the catalytic activity of the complexes as grafted materials.