Photophysical studies of hetero-bischelated complexes of rhodium(III) containing 2,2′-dipyridylamine

Four hetero-bischelated Rh(III) complexes containing HDPA (1 and 2) or DPA− (3 and 4) have been synthesized (HDPA = 2,2′-dipyridylamine; DPA− = the deprotonated form of HDPA). At 77 K, 1 and 2 in EtOH/MeOH (4:1, v/v), each show a broad, symmetric and structureless red emission assigned as dd* phosphorescence; whereas 3 and 4, each show a broad, asymmetric and structureless blue emission. Based on the luminescence and electrochemical data, the emission of 3 and 4 are assigned as πd* phosphorescence.