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The trinuclear [{Ru(NH3)4(py-COOH)}(μ-CN){Ru(bpy)2}(μ-CN){Ru(NH3)4(py-COOH)}]6+ (py-COOH = isonicotinic acid, bpy = 2,2'-bipyridine) (1) and dinuclear [{Ru(dcb)2}2L]7- (dcb = 2,2'-bipyridine-4,4'-dicarboxylic acid, H3L = 9-phenyl-2,3,7-trihydroxy-6-fluorone) (2) complexes were prepared and their spectroelectrochemical behaviour characterised in solution and on conductive glass electrodes layered with Sb-doped nanocrystalline SnO2. The systems display a reversible redox response in a narrow potential range (-0.5 to +0.5 V vs SCE) and offer the possibility of controlling colour changes of electrochromic devices through variations of the coordinated and bridging ligands at the metal centres. SnO2(Sb) electrodes loaded with these dyes show switching times of the order of ms.

We describe a convergent synthesis of eight 1,3,5- and 1,2,4,5-substituted benzene derivatives with long rigid arms containing 4-pyridyl, 2,2'-bipyridyl, and 2,2'-bipyrimidyl termini, meant to be used as trigonal or tetragonal connectors for the construction of large molecular structures. The synthesis involved copper-free Pd-mediated coupling of terminal acetylenes to aryl halides. First, one of the termini of 1,3-diethynylbicyclo[1.1.1]pentane was coupled with a brominated aza heterocycle, and second, 3 equiv of the resulting extended arm were coupled with 1,3,5-triiodobenzene or 4 with 1,2,4,5-tetraiodobenzene. An improved large-scale synthesis for 1,3-diethynylbicyclo[1.1.1]pentane is described. The structures of two of the arms were determined by single-crystal X-ray analysis. Several long molecular rods with 4-pyridyl termini were obtained as byproducts, and a single-crystal X-ray structure is reported for the shortest of these.