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A series of [Pt(ii)(diimine)(dithiolate)] complexes of general formula [Pt{X,X'-(CO(2)R)(2)-bpy}(mnt)] (where X = 3, 4 or 5; R = H or Et, bpy = 2,2'-bipyridyl and mnt = maleonitriledithiolate), have been spectroscopically, electrochemically and computationally characterised and compared with the precursors [Pt{X,X'-(CO(2)R)(2)-bpy}Cl(2)] and X,X'-(CO(2)R)(2)-bpy. The study includes cyclic voltammetry, in situ EPR spectroelectrochemical studies of fluid solution and frozen solution samples, UV/Vis/NIR spectroelectrochemistry, hyrid DFT and TD-DFT calculations. The effect of changing the position of the bpy substituents from 3,3' to 4,4' and 5,5' is discussed with reference to electronic changes seen within the different members of the family of molecules. The performance of the mnt complexes in dye-sensitised solar cells has been previously described and the superior performance of [Pt{3,3'-(CO(2)R)(2)-bpy}(mnt)] is now explained in terms of decreased electronic delocalisation through twisting of the bipyridyl ligand as supported by the EPR and computational results.

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We thank EaStChem for studentship funding (CLL) and the EPSRC Supergen programme for further finacial support. This work has made use of the resources provided by the EaStCHEM Research Computing Facility, partially supported by the eDIKT initiative.

The control of the loss mechanism in a dye sensitised solar cell (DSSC) via recombination of the injected electron with the oxidised dye was investigated by incorporating a redox-active ligand, 6,7-bis(methylthio)tetrathiafulvalene dithiolate (TTF(SMe)(2)), into a ruthenium bipyridyl dye. A series of dyes with general formula [Ru(4,4'-R-bpy)(2)(TTF(SMe)(2)], where R = H, CO(2)Et and CO(2)H, were synthesised and characterised using electrochemistry, absorption and emission spectroscopy, spectroelectrochemistry and hybrid-DFT calculations. In addition, the performance of the acid derivative in a DSSC was investigated using IV measurements, as well as transient absorption spectroscopy. These complexes showed significant TTF-ligand character to the HOMO orbital, as deduced by spectroelectrochemical, emission and computational studies. Upon adsorption of the acid derivative to TiO(2) a long-lived charge-separated state of 20 ms was observed via transient absorption spectroscopy. Despite this long-lived charge-separated state, the dye yielded extremely low DSSC efficiencies, attributed to the poor regeneration of the neutral dye by iodide. As a result, the complex forms a novel long-lived charge separated state that persists even under working solar cell electrolyte conditions.

Selected ruthenium complexes [Ru(trpy)L], [Ru(bpy)2L], and [Ru(dcbpy)2L] were chemisorbed onto the surface of nanocrystalline titanium dioxide. The ligands (L) were Cl ions or cyanodithioimidocarbonate (C2N2S2), so the type of linkage with the TiO2 surface was different in each case. The resulting materials were sensitive to visible light. Photoelectrochemical studies revealed significant, potential-dependent photosensitization in the 300–650 nm window. In addition, the direction of the photocurrent could be switched from cathodic to anodic and vice versa by application of adequate external potential. Further photoelectrochemical, spectroscopic and theoretical studies allowed prediction of the possible mechanism of current switching. The photoelectrochemical properties of those materials allow construction of optoelectronic ternary logic devices.

We prepared the complexes [Ru{4,4Ј-(CO 2 R-bpy) 2 }{Cu-(exoO 2 -cyclam)}][NO 3 ] 2 [R = Et (1), H (2)], which possess a Cu II centre covalently linked to a (bipyridyl)Ru II fragment. The complexes were characterised by cyclic voltammetry, UV/Vis spectroscopy, hybrid DFT and TD-DFT (time-dependent density-functional theory) calculations, EPR (electron paramagnetic resonance), emission spectroscopy and UV/Vis spectroelectrochemistry, with the latter showing reversible conversion to the mono-and di-oxidised and monoand di-reduced species. The data suggest the first oxidation to be largely based on the Ru centre but with little energetic difference between the highest occupied orbitals based on Ru and based on Cu. There was also evidence of solvent co-