New members of a class of cyclometalated 1,3-di-(2-pyridyl)benzene platinum(II) complexes bearing a tetrazole-thiolate ancillary ligand

Substitution of the chlorido ligand of the cyclometalated complexes [Pt(5-R-dpyb)Cl] (R = methyl, 2-thienyl; dpyb = 1,3-di(2-pyridyl)benzene) by 1-phenyl-1H-tetrazole-5-thiolate leads to the related thiolato complexes [Pt(5-R-dpyb)(1-phenyl-1H-tetrazole-5-thiolate)], which have been fully characterised. Their photophysical properties were determined in degassed dichloromethane solution at room temperature. It turned out that the color of the phosphorescence can be tuned by the nature of the substituents on the benzene ring, with the introduction of a donor group such as 2-thienyl allowing a large red-shift of the emission. Substitution of the chloride ligand with 1-phenyl-1H-tetrazole-5-thiolate has a negligible effect on the emission maxima and life-times, since both parameters remain in a narrow range which is very close to the original value. However, the use of this thiolate as ancillary ligand can lead to very high quantum yields, approaching unity.