An electrostatically self-assembled hybrid film based on dinuclear ruthenium(II) polypyridyl complex and europium-substituted tungstoborate

A new electrostatically self-assembled hybrid film consisting of alternating layers of europium-substituted tungstoborate anion of [Eu(BW11O39)2]15− (EuBW) and dinuclear ruthenium(II) polypyridyl complex cation of [(bpy)2Ru(BPBH)Ru(bpy)2]4+ {in which bpy = 2,2′-bipyridine and BPBH = 1,6-bis-(2-(2-phenyl)benzimidazoyl)hexane, RuBPBH} was successfully prepared. UV–vis absorption spectroscopy provided the evidences for the layer-by-layer deposition of EuBW anion and RuBPBH cation on quartz substrate. The (EuBW/RuBPBH)n films showed stable electrochemical and photoelectrochemical properties with a photocurrent density of 2.66 μA/cm2 being found for a 4-layer film of (EuBW/RuBPBH)4, while irradiated with polychromatic light (325 nm < λ < 730 nm) at an applied potential of −0.3 V versus saturated calomel electrode. The enhanced photocurrent generation by presence of the EuBW layer in this hybrid film has also been demonstrated as compared to the (PSS-c-MS/RuBPBH)1 film by using a photoelectrochemical inactive polyanion of PSS-c-MS instead of the EuBW anion.