Cyclometalated rhodium complexes of phenyl- and diphenyl-substituted oxazole and thiazole luminophores
摘要:
Cyclometaleted rhodium complexes of oxazole and thiazole luminophores [Rh((CaN)-N-boolean AND)(2)En]Cl [((CaN)-N-boolean AND)(-), deprotonated forms of 2,5-diphenyloxazole, 2-phenylbenzothiazole, 2-(biphenyl-4-yl)-6-phenylbenzoxazole, and 2-(biphenyl-4-yl)-5-phenyloxazole; En - ethylenediamine] were obtained and characterized by the methods of H-1 NMR, IR, and electron absorption and emission spectroscopy. Two cyclometallated ligands in the inner sphere of the complexes are in the cis-C,C positions. Cyclometallating of the luminophores results both in a red shift of intraligand pi-pi*-optical transitions (Delta nu similar to 1.2 kK) as compared to free luminophores and in the appearance of a long-wave band (lambda(max) 376-392 nm) of a mixed nature: metal-ligand charge transfer/intraligand transition. Alongside with the internal conversion to a low-energy state of the metal-ligand charge transfer/ intraligand transition, the emission degradation of photoexcitation energy results in the intraligand pi-pi*-fluorescence of the complexes (lambda(max) 390-423 nm) at room temperature.