Synthesis, characterisation, electrochemical study and photovoltaic measurements of a new terpyridine and pyridine-quinoline based mixed chelate ruthenium dye

A novel ruthenium-terpyridine based photosensitiser, Ru[(p-F-tpy)(pcqH)Cl] PF6 (p-F-tpy = 4′-(4-fluorophenyl)-2,2′:6′,2″-terpyridine, pcqH = 2-(2-pyridyl)-4-carboxyquinoline) is reported here. The pKa of the -COOH group in the free ligand is 3.56, which reduces to 2.89 when bound to the metal. The electronic spectrum of the complex shows the lowest energy MLCT band at 536 nm in DMSO. A Pourbaix diagram for the Ru-aquo species has been constructed to show the detailed redox properties of the complex by means of cyclic voltammetry and differential pulse voltammetry at variable pH. DFT and TDDFT calculations have been performed on the complex.102