Iron(III) Complexes with Luminescence Lifetimes of up to 100 ns to Enhance Upconversion and Photocatalysis.

Iron is the most abundant transition metal element and would be the ideal replacement for noble metals in many applications that rely on luminescent and long-lived electronically excited states. We show that efficient reversible energy transfer between doublet excited states of iron complexes and triplet excited states on organic ligands improves energy storage by up to 350-fold. As a result, luminescence lifetimes of up to 100 ns are achieved, the upconversion from red to blue light becomes 68 times more efficient and the yield of benchmark photoredox reactions is significantly improved. These advances make iron coordination compounds more promising candidates for applications in lighting, solar energy conversion and photocatalysis.