文摘
The complexes [Ru(qpy)LL′]2+ (qpy = 2,2′:6′,2″:6″,2‴-quaterpyridine), with 1: L = acetonitrile, L′= chloride; 2: L = L′= acetonitrile; and 3: L = L′= vinylpyridine, have been prepared from [Ru(qpy) (Cl)2]. Their absorption spectra in CH3CN exhibit broad metal-to-ligand charge transfer (MLCT) absorptions arising from overlapping 1A1 → 1MLCT transitions. Photoluminescence is not observed at room temperature, but all three are weakly emissive in 4:1 ethanol/methanol glasses at 77 K with broad, featureless emissions observed between 600 and 1000 nm consistent with MLCT phosphorescence. Cyclic voltammograms in CH3CN reveal the expected RuIII/II redox couples. In 0.1 M trifluoroacetic acid (TFA), 1 and 2 undergo aquation to give [RuII(qpy)(OH2)2]2+, as evidenced by the appearance of waves for the couples [RuIII(qpy)(OH2)2]3+/[RuII(qpy)(OH2)2]2+, [RuIV(qpy)(O)(OH2)]2+/[RuIII(qpy)(OH2)2]3+, and [RuVI(qpy)(O)2]2+/[RuIV(qpy)(O)(OH2)]2+ in cyclic voltammograms.
