Lanthanide complexes of a cyclen derivative with phenylphosphinic pendant arms for possible 1H and 31P MRI temperature sensitive probes

Abstract

Lanthanide complexes of 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetrakis[methylene(phenylphosphinic) acid] (H₄L) were found to give a linear correlation of ¹H and ³¹P NMR chemical shifts to temperature in the physiologically relevant temperature range, with dependencies comparable or better than those found for existing complexes; due to the greater hydrophobic character of the ligand the complexes may exhibit a different biodistribution in the body.