An overview of phosphorescent metallomesogens based on platinum and iridium

Metal atoms with excellent magnetic, electrical and optical properties that are integrated into liquid crystal molecules - metallomesogens - have attracted much attention from chemists, physicists and engineers and many materials based on e.g. Ag, Pt, Pd, Ir, Ni, Cu and lanthanide ions have been reported. Though several reviews and books have been published on metallomesogens, few refer to their photophysical properties. Additionally, metallomesogens with good emission properties in solution or in neat film are still scarce. Owing to the 100% theoretical internal quantum efficiency, phosphorescent liquid-crystalline materials were developed recently. Here, a brief overview of recent research on such materials based on platinum and iridium complexes including their molecular design and structure-property relationships is reported. It is hoped that this review will stimulate further development of luminescent metallomesogens.