Synthesis and Photophysical Evaluation of 3,3’-Nitrogen Bis-Substituted fac-[Re(CO)3(Diimine)Br] Complexes

The preparations, photophysical and electrochemical properties of a series of fac-[Re(CO)₃(diimine)Br] complexes are presented. The bipyridine (bpy) based diimine ligands feature symmetrical and asymmetrical 3,3’-diamino-2,2’-bipyridine substitution patterns. Photophysical and electrochemical properties of these complexes are tunable, depending on their organic diimine framework. Introduction of a distal urea bridge via the 3,3’-substitution pattern led to prolonged phosphorescence lifetimes without a significant change in absorbance and phosphorescence emission wavelengths. Reversible electrochemical bipyridine reduction remained largely unchanged by this derivatization.