Synthesis and photophysical properties of hetero-bischelated complexes of rhodium(III) containing phenyl-pyridin-2-ylmethylene-amine

Three new hetero-bischelated rhodium (111) complexes of cis-[Rh(PA)(L)Cl-2]Cl (where PA = phenylpyridin-2-ylmethylene-amine; L = 2,2'-bipyridine, 2,2'-dipyridylamine and 1,10-phenanthroline) have been successfully prepared and characterized. Each complex shows high intensity bands in the UV region, and these are assigned to spin-allowed pi-pi* transitions. The medium-intensity absorption band profile in the lower energy region can be explained by convolution of spin-allowed CT and d-d* transitions. The emission spectra at low temperature (77 K) of these complexes in EtOH/MeOH (4:1 v/v) are virtually identical. They all exhibit a broad, symmetric, and structureless red emission with a microsecond lifetime and hence are assigned as the d-d* phosphorescence.