Texaphyrin sensitized near-IR-to-visible photon upconversion

摘要: Near-IR (NIR) absorption from a Cd(II) texaphyrin (TXP) has been successfully coupled with rubrene triplet acceptors/annihilators in vacuum degassed dichloromethane to upconvert NIR (670–800 nm) incident photons into yellow fluorescence through sensitized triplet–triplet annihilation. Stern–Volmer analysis of dynamic energy transfer quenching TXP by using transient spectroscopy revealed and bimolecular constants 21 000 M−1 5.7 × 108 s−1 respectively, for the process. The upconverted emission intensity respect excitation power density at 750 nm was shown vary between quadratic linear, illustrating expected kinetic limits light producing photochemistry under continuous wave illumination. Furthermore, increasing sensitizer concentration, characteristic quadratic-to-linear crossover point shifted lower photon density. This is consistent notion that stronger capture leads experimental conditions promoting upconversion milder conditions. maximum quantum yield TXP-sensitized 1.54 ± 0.04% dilute determined relative [Os(phen)3](PF6)2 saturating efficiency realized when dependence reached constant over region where composition displayed linear response In pulsed laser experiments higher concentrations, annihilation saturate approximately 13%, corresponding an ∼10%, suggesting solvent either lowers T2 state acceptor or somehow attenuating reaction excited triplets.