Structural and photophysical characterisation of coordination and optical isomers of mononuclear ruthenium(II) polypyridyl 1,2,4-triazole complexes

The X-ray crystal structure of the N-2 isomers of the Ru(bipy)(2) complexes of Hphpztr (1) and Hpztr (2), (bipy = 2,2'-bipyridine, Hphpztr = 2-(5'-phenyl-4' H-[1,2,4] triazol-3'-yl) pyrazine and Hpztr = 2-(4' H-[1,2,4] triazol-3'-yl) pyrazine) are reported. The molecular structure obtained for 2 demonstrates an interesting structural aspect in the sharing of a single proton between two molecular units. The isolation of the Delta and Lambda stereoisomers of 1 and [Ru(phen)(2)(pztr)](+) (phen = 1,10-phenanthroline) (3) by semipreparative HPLC is also reported. The compounds obtained are characterised by electronic spectroscopy and particular attention is paid to the photophysical properties of Delta and Lambda isomers of 1 and 3, in chiral enantiopure and racemic solvents.