A Carbazole‐Containing Difunctional RuII Complex That Functions as a pH‐Induced Emission Switch and an Efficient Sensitizer for Solar Cells

TLDR: A heteroleptic ruthenium(II) complex of [Ru(Hecip)(Hdcbpy) (NCS)2]·[N(C4H9)4]+ has been synthesized and characterized by elementary analysis, cyclic voltammetry, MALDI-TOF mass spectrometry, and 1H NMR, IR, UV/Vis absorption, and emission spectroscopy.

Abstract: A heteroleptic ruthenium(II) complex of [Ru(Hecip)(Hdcbpy) (NCS)2]–·[N(C4H9)4]+ (where Hecip = 2-(9-ethyl-9H-carbazol-3-yl)-1H-imidazo[4,5-f][1,10]phenanthroline and Hdcbpy = monodeprotonated 2,2′-bipyridyl-4,4′-dicarboxylic acid) has been synthesized and characterized by elementary analysis, cyclic voltammetry, MALDI-TOF mass spectrometry, and 1H NMR, IR, UV/Vis absorption, and emission spectroscopy. The ground- and excited-state acid–base properties of the complex have been studied by means of UV/Vis absorption spectrophotometric and spectrofluorimetric titrations in a Britton–Robinson/DMF (v/v, 4:1) buffer solution. The complex was found to act as pH-induced off-on-off/on-off-on-off-type emission switch, when excited at 530/470 nm, with a protonation/deprotonation reaction taking place near the physiological pH range. The performance of the complex-sensitized TiO2 nanocrystalline solar cell with 0.05 M I2 and 0.5 M LiI in 50 % acetonitrile and 50 % propylene carbonate (PC) as the electrolyte solution and a platinum film as the counter electrode has also been studied, and was compared to that of the cis-[Ru(H2dcbpy)2(NCS)2] (N3)-sensitized solar cell under the same experimental conditions.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)