Singlet oxygen-responsive photorelease of tyramine

Abstract

A system capable of photoreleasing tyramine has been developed. The photodonor system consists of an isoindole cage of tyramine and a biscyclometalated Ir(III) complex singlet oxygen (O-1(2)) photosensitizer. Photoirradiation at a wavelength of 365 nm produces tyramine, as evidenced by mass spectrometry and H-1 NMR spectroscopy. The photorelease proceeds through two steps involving the formation of a Diels-Alder-type [2 + 4] cycloadduct of O-1(2), followed by the slow and spontaneous decomposition of the adduct into tyramine and 2-benzoylbenzophenon.