Long-lived near-infrared luminescent lanthanide complexes of imidodiphosphinate 'shell' ligands

The synthesis and characterization of near-infrared (NIR) emitting complexes of Nd(III), Er(III) and Yd(III) based on hexacoordinate lanthanide ions with an aryl functionalized imidodiphosphinate ligand, tpip, are described. The results indicate the effective shielding of the lanthanide by the twelve phenyl groups of the tpip ligands and the reduction of high-energy vibrations in close proximity to the lanthanide, which are the two important features in the design of NIR emitting lanthanide complexes.