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Abstract
Caged compounds have been used in biochemistry and physiology for over two decades. BHQ compounds were found to protect bioactive functional groups and release the substrate effectively upon irradiation of light. BHQ-protected carboxylates, phosphates, and glycerol derivatives were synthesized and tested for their photochemical and photophysical properties. BHQ protected compounds were found to be sensitive to both 1PE and 2PE processes. The one-photon quantum efficiencies were found to be 0.29-0.39 upon irradiation with 365-nm UV light. The two-photon uncaging action cross-sections were determined to be 0.43-0.90 GM upon irradiation with 740-nm IR laser light. The dark hydrolysis rates of BHQ-caged compounds under simulated physiological conditions were found to be 69-105 h. Stern-Volmer quenching experiments, a photolysis in oxygen-18 labeled water, NMR observation of BHQ-OAc photolysis in acetonitrile-d3, and time-resolved spectroscopic studies were executed to understand the photolysis mechanism of BHQ, which is proposed to be a solvent assisted heterolysis mechanism involving a short-lived triplet state. BHQ-caged ATP was synthesized and examined for its photochemistry as a biologically useful, temporally and spatially controlled ATP releasing reagent.