Photon Upconversion Using Baird-Type (Anti)Aromatic Quinoidal Naphthalene Derivative as a Sensitizer

A naphtho-p-quinodimethane (QDM) exhibiting Baird’s 4n – π antiaromaticity was used as green photons-harvesting chromophore to sensitize perylene (Per) leading to upconverted blue photoluminescence. The solution phase QDM → Per triplet energy transfer (TET) could not be unraveled via the Stern–Volmer method, but transient absorption measurements revealed that the kinetics of T1 → Tn for QDM (τ = 1.4 μs) was 1 order of magnitude reduced (τ = 0.17 μs) as a result of 3(Per)* formation. Furthermore, we demonstrated that incident light with power densities in the microwatt regime is sufficient to perform photon upconversion using the present set of molecular systems.