Spectral, Structural, and Computational Studies of a New Family of Ruthenium(II) Complexes Containing Substituted 1,10‐Phenanthroline Ligands and in situ Electropolymerization of a Phenanthrolineruthenium(II) Complex Bridging Nanogap Gold Electrodes

The synthesis and spectral and structural characterization of a new family of ruthenium(II) complexes containing 3‐bromo‐, 3,8‐dibromo‐, 3‐(thiophen‐2′,2″‐yl)‐, and 3,8‐(thiophen‐2′,2″‐yl)‐1,10‐phenanthroline (phen) ligands is described. UV/Vis spectroscopy is used to compare the differences between the conjugated π systems in these ligands and their respective [Ru(bpy) 2 ] 2+ (bpy = 2,2′‐bipyridine) analogs. Density functional theory (DFT) computations have been carried out to compare the energy differences between the single‐crystal and the energy‐minimized structures for different conformations ( trans / trans , trans / cis and cis / cis ) of the thiophene rings and their bonded phen ring. The formation of an oligothiophene semiconductor polymer bridging gold electrodes with a gap of around 25 nm gap from Ru II complex 7 by in situ electropolymerization, and its removal, is monitored by scanning electron microscopy (SEM). (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)