Metal-organic materials with circularly polarized luminescence

Chirality is ubiquitous in nature, and circularly polarized luminescence (CPL) is one of the key features of some chiral non-racemic luminescent systems. Among the developed CPL-active systems, chiral metal–organic materials (MOMs) have become tremendously meaningful due to the combination of coordination-bonded metal centers and organic ligands. This brings specific opportunities in the design of novel structures including coordination polymers, discrete supramolecular assemblies, and other types of coordination complexes with molecular or supramolecular-leveled chirality, which can be originated from ligand or metal-based chirogens and luminogens. In these chiral MOMs, CPL properties might be aroused or amplified under suitable arrangement of chirogens and luminogens, for which, effective strategies like controlled self-assembly for helicity amplification, aggregation of luminogens, charge transfer, energy transfer, etc, have been put forward. As a result, exciting potential applications have been found in such fields as CPL-OLED, stereo-biochemistry and biomedicine, chiral recognition and sensing, chiroptical photoswitches, security devices and so on. In this review, we will mainly discuss the recent progress made in CPL MOMs, including the basic concepts, major parameters and characterization methods, mechanism and designing origins, different structural categories, effective strategies to enhance CPL performance, as well as their practical applications and prospects.