Luminescent d8 metal complexes of platinum(II) and gold(III): From photophysics to photofunctional materials and probes

Among various phosphorescent metal complexes, the spectroscopic and luminescence properties of d8 transition metal complexes have increasingly attracted much attention. In particular, there has been a growing interest in the exploration of luminescent platinum(II) and gold(III) complexes of square-planar geometry and coordinate-unsaturation. Their square-planar geometry has enabled them to come close to each other to form stacking interaction, as exemplified by the platinum(II) complexes, which possess rich photophysical properties that are associated with their facile access to noncovalent Pt(II)···Pt(II) and π–π stacking interactions. The ready tunability of the luminescence features through ligand design has also been exemplified by the gold(III) complexes. In this article, the photophysical behaviors of luminescent platinum(II) and gold(III) complexes will be described. Our recent advances in using these complexes for various applications will also be described, as illustrated by selected examples.