Homoleptic Ru(II) complex with terpyridine ligands appended with terthiophene moieties. Synthesis, characterization and electropolymerization

A new Ru(II) complex, [Ru(TTT)2][PF6]2 (TTT = 4’-[(2,2’:5’,2”-terthien-3’-yl)methoxy]-2,2’:6’,2”-terpyridine) has been synthesized and characterized by 1H NMR and UV-Vis spectroscopy and by cyclic voltammetry. The electrosynthesis of the corresponding conductive polymer, P[Ru(TTT)2], is reported, as well as its voltammetric and spectroelectrochemical characterization. The comparison between [Ru(TTT)2][PF6]2 and TTT voltammetric data shows that the presence of the metal ion makes easier the oxidation and the polymerization of the organic framework. On the other hand, UV-Vis data confirm that the presence of the –O-CH2-spacer between coordinating and polymerizing unit (terpyridine and terthiophene, respectively) reduces the electronic delocalization among these moieties, analogously to that observed in the TTT ligand alone. As far as P[Ru(TTT)2] is concerned, the voltammetric characterization evidences the so-called ‘charge-trapping phenomena, already observed also in PTTT, too. Moreover, spectroelectrochemical characterization shows a likely overlapping of the p-p* polymer and MLCT complex absorption bands, causing a bathocromic shift with respect to PTTT.