100 μs Luminescence Lifetime Boosts the Excited State Reactivity of a Ruthenium(II)-Anthracene Complex in Photon Upconversion and Photocatalytic Polymerizations with Red Light

The triplet excited state lifetime of a photosensitizer is an essential parameter for diffusion-controlled energy- and electron-transfer, which occurs usually in a competitive manner to the intrinsic decay of a triplet excited state. Here we show the decisive role of luminescence lifetime in the triplet excited state reactivity toward energy- and electron transfer. Anchoring two phenyl anthracene chromophores to a ruthenium(II) polypyridyl complex (Ru^II ref) leads to a Ru^II triad with a luminescence lifetime above 100 μs, which is more than 40 times longer than that of the prototypical complex. The obtained Ru^II triad sensitizes energy transfer to anthracene-based annihilators more efficiently than Ru^II ref and enables red-to-blue photon upconversion with a pseudo anti-Stokes shift of 0.94 eV and a moderate upconversion efficiency near 1 % in aerated solution. Particularly, Ru^II triad allows rapid photoredox catalytic polymerizations of acrylate and acrylamide monomers under aerobic condition with red light, which are kinetically hindered for Ru^II ref. Our work shows that excited state lifetime of a photosensitizer governs the dynamics of the excited state reactions, which seems an overlooked but important aspect for photochemistry.