INOR 698

The complexes with 5,5'-amino substituted bipyridine ligands have higher energy absorption than the complexes with 4,4'-amino substituted bipyridine lignds. These indicate complexes with 5,5'-amino bipyridine has a less distorted excited-state or has a stronger electron donating ligand. At room temperature, the UV-Vis absorption and emission spectra of these complexes do not have obvious change at acidic or basic conditions. However, at 77 K, the emission spectra are quite different. The emission maximum shifts to lower energy in basic solution (pH 13.5), while blue-shift in acidic solution (pH 2.1). The complexes with 5,5'-amino substituted bipyridine ligands tend to less sensitive to the pH than the complexes with 4,4'-amino substituted bipyridine lignds.