Dual Application of (Aqua)(Chlorido)(Porphyrinato)Chromium(III) as Hypersensitive Amine-Triggered ON Switch and for Dioxygen Activation

Although synthesis and substitution reactions of chlorido chromium­(III) porphyrins Cr^III(TPP)­(Cl)­(L) (H₂TPP = 5,10,15,20-tetraphenyl porphyrin, L = pyridine, H₂O, ROH, etc.), have been well-established in coordination chemistry for decades, an unexpected dichotomous reactivity of Cr^III(TPP)­(Cl)­(H₂O) (1) toward amines is disclosed here. This reactivity leads to the application of 1 as highly sensitive substoichiometric and irreversible ON switch for amine detection by an autocatalytic pathway. The concomitant activation of O₂ by the 1/amine system is furthermore exploited in an electrochemically driven epoxidation of norbonene using O₂ as initial oxidant.