Variable Photophysical Properties of Phosphorescent Iridium(III) Complexes Triggered by closo‐ and nido‐Carborane Substitution

Phosphorescent iridium(III) complexes with three bidentate carborane-functionalized ligands have been synthesized. The luminescent efficiency of the o-carborane-based facial complex fac-o shows solvent-molecule dependence both in solution and solid state that is related to the dielectric constant. The water-soluble and high phosphorescence-efficient nido complex nido-fac-o can be used in fluorescence lifetime bioimaging.