Rhenium(I) tricarbonyl complexes with bispyridine ligands attached to sulfur-rich core: Syntheses, structures and properties

Rhenium(I) tricarbonyl complexes with bispyridine ligands bearing sulfur-rich pendant, Re(CO)(3)(Medpydt)X (Medpydt = dimethyl 2-(di(2-pyridyl)methylene)-1,3-dithiole-4,5-dicarboxylate; X = Cl, 1; X = Br, 2) and Re(CO)(3)(MebpyTTF)X (MebpyTTF = 4,5-bis(methyloxycabonyl)-4',5'-(4'-methyl-2,2'-dipyrid-4-ylethylenedithio)-tetrathiafulvalene; X = Cl, 5; X = Br, 6), were prepared from the reactions between Re(CO)(5)X (X = Cl, Br) and Medpydt or MebpyTTF, respectively. Hydrolysis of the above complexes afforded the analogues with carboxylate derivatives, Re(CO)(3)(H(2)dpydt)X (X = Cl, 3; X = Br, 4) and Re(CO)(3)(H(2)b-pyTTF)X (X = Cl, 7; X = Br, 8). The crystal structures for complexes 1 center dot 2H(2)O, 5 and 6 were determined using X-ray single crystal diffraction. UV-Vis absorption spectra of the rhenium complexes show the intraligand and MLCT transitions. Electrochemical behaviors of all new compounds were studied with cyclic voltammetry. Upon irradiation, complexes 3-6 exhibit blue to red emissions in fluid solutions at the room temperature. The performance of complexes 3, 4, 7 and 8 as photosensitizers for anatase TiO2 solar cells was preliminarily investigated as well. (C) 2008 Elsevier B.V. All rights reserved.