I will discuss recent developments and future directions of research on photoactive coordination compounds made from non-precious transition metal elements instead of conventionally used noble metals. I will focus on well-characterized complexes with excited state lifetimes ranging from subpicoseconds to milliseconds in solution. The nature of the excited states comprise spin-flip, ligand-to-metal and metal-to-ligand charge transfer states. Emerging applications cover sensing, luminescence, photocatalysis and upconversion.
