Photoactivatable, biologically-relevant phenols with sensitivity toward 2-photon excitationElectronic supplementary information (ESI) available: Synthetic procedures for the preparations of 1b, 2-7, 10b, and 11-16; 1H NMR and 13C NMR spectra; experimental procedures for determining , Qu, and δu; and individual photolysis reaction progress curves. See DOI: 10.1039/c5pp00334b

• Main Authors: McLain, Duncan E, Rea, Adam. C, Widegren, Magnus B, Dore, Timothy M
• Format: Article
• Language: English
• ISSN: 1474-905X; 1474-9092
• DOI: 10.1039/c5pp00334b

Spatio-temporal release of biologically relevant small molecules provides exquisite control over the activation of receptors and signaling pathways. This can be accomplished via a photochemical reaction that releases the desired small molecule in response to irradiation with light. A series of biologically-relevant signaling molecules (serotonin, octopamine, capsaicin, N -vanillyl-nonanoylamide, estradiol, and tyrosine) that contain a phenol moiety were conjugated to the 8-bromo-7-hydroxyquinolinyl (BHQ) or 8-cyano-7-hydroxyquinolinyl (CyHQ) photoremovable protecting groups (PPGs). The CyHQ caged compounds proved sensitive toward 1PE and 2PE processes with quantum efficiencies of 0.2-0.4 upon irradiation at 365 nm and two-photon action cross sections of 0.15-0.31 GM when irradiated at 740 nm. All but one BHQ caged compound, BHQ-estradiol, were found to be sensitive to photolysis through 1PE and 2PE with quantum efficiencies of 0.30-0.40 and two photon cross sections of 0.40-0.60 GM. Instead of releasing estradiol, BHQ-estradiol underwent debromination. Quinoline-based photoremovable protecting groups mediate the photoactivation of the signaling molecules serotonin, octopamine, capsaicin, N -vanillyl-nonanoylamide, estradiol, and tyrosine through 1- and 2-photon excitation and enable physiological studies.