Two-photon photosensitized production of singlet oxygen: Sensitizers with phenylene-ethynylene-based chromophores

Article abstract of DOI:10.1021/jo0482099

(Chemical Equation Presented) Singlet molecular oxygen (a ¹Δ_g) has been produced and optically monitored in time-resolved experiments upon nonlinear two-photon excitation of photosensitizers that contain triple bonds as an integral part of the chromophore. Both experiments and ab initio computations indicate that the photophysical properties of alkyne-containing sensitizers are similar to those in the alkene-containing analogues. Most importantly, however, in comparison to the analogue that contains double bonds, the sensitizer containing alkyne moieties is more stable against singlet-oxygen-mediated photooxygenation reactions. This increased stability can be advantageous, particularly with respect to two-photon singlet oxygen imaging experiments in which data are collected over comparatively long time periods.