Abstract
Photoremovable protecting groups (PPGs) represent one of the main contemporary implementations of photochemistry in diverse fields of research and practical applications. For the past half century, organic and metal-complex PPGs were considered mutually exclusive classes, each of which providing unique sets of physical and chemical properties thanks to their distinctive structures. Here, we introduce the meso-methylporphyrin group as a prototype hybrid-class PPG that unites traditionally exclusive elements of organic and metal-complex PPGs within a single structure. We show that the porphyrin scaffold allows extensive modularity by functional separation of the metal-binding chromophore and up to four sites of leaving group release. The insertion of metal ions can be used to tune their spectroscopic, photochemical, and biological properties. We provide a detailed description of the photoreaction mechanism studied by steady-state and transient absorption spectroscopies and quantum-chemical calculations. Our approach applied herein could facilitate access to a hitherto untapped chemical space of potential PPG scaffolds.
Content

Supplementary material

Supplementray Information
All the data generated or analyzed during this study. Supporting figures, Materials and Methods, Synthesis and characterization, Quantum Chemical Calculations.

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Crystallographic data of compound 6-Zn
Crystallographic data have been deposited at the Cambridge Crystallographic Data Centre (CCDC) as 1973540 and can be obtained free of charge from the CCDC via www.ccdc.cam.ac.uk/getstructures.