Boron-Functionalized Phosphorescent Iridium(III) Complexes

Abstract

Boron-based motifs, introduced into π-conjugated systems in various forms (e.g., triarylboranes, borate dyes, and boron clusters), have attracted much attention owing to their unique electronic and structural features. Recently, organoboron groups – mainly triarylboranes and boron clusters (carboranes) – that exhibit highly polarizable σ-aromatic character and strongly electron-withdrawing properties have been widely incorporated into phosphorescent IrIII complexes. These organoboron groups make significant contributions to the excited states of such IrIII complexes, allowing tuning of phosphorescence energy and quantum yields. A number of fascinating boron-functionalized IrIII complexes have been synthesized to date, and some of them have been applied in various fields, including those of organic light-emitting diodes, chemosensors, and biological probes. This microreview provides a summary of recent research into boron-functionalized IrIII complexes, emphasizing the impact of organoboron groups on photophysical properties and their optoelectronic applications.