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 provided 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.

光可去除保护基 (PPG) 代表了光化学在不同研究领域和实际应用中的主要当代应用之一。在过去的半个世纪里，有机和金属复合物 PPG 被认为是相互排斥的类别，由于其独特的结构，每一种都提供了独特的物理和化学性质。在这里，我们介绍meso-甲基卟啉基团作为混合型 PPG 的原型，将传统上独有的有机和金属复合 PPG 元素结合在一个结构中。我们表明，卟啉支架通过金属结合发色团的功能分离和多达四个离去基团释放位点实现了广泛的模块化。金属离子的插入可用于调整其光谱、光化学和生物学特性。我们详细描述了通过稳态和瞬态吸收光谱和量子化学计算研究的光反应机制。我们在此应用的方法可以促进访问迄今为止尚未开发的潜在 PPG 支架化学空间。