We investigate a biomimetic model of a Tyr_Z/His₁₉₀ pair, a hydrogen‐bonded phenol/imidazole covalently attached to a porphyrin sensitizer. Laser flash photolysis in the presence of an external electron acceptor reveals the need for water molecules to unlock the light‐induced oxidation of the phenol through an intramolecular pathway. Kinetics monitoring encompasses two fast phases with distinct spectral properties. The first phase is related to a one‐electron transfer from the phenol to the porphyrin radical cation coupled with a domino two‐proton transfer leading to the ejection of a proton from the imidazole–phenol pair. The second phase concerns conveying the released proton to the porphyrin N₄ coordinating cavity. Our study provides an unprecedented example of a light‐induced electron‐transfer process in a Tyr_Z/His₁₉₀ model of photosystem II, evidencing the movement of both the phenol and imidazole protons along an isoenergetic pathway.

中文翻译：

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在光系统II的酪氨酸/组氨酸（Tyr / His）模型中，水分子门控光诱导的单电子二质子转移

我们研究了Tyr _Z / His ₁₉₀对的仿生模型，该对是共价附于卟啉敏化剂的氢键酚/咪唑。存在外部电子受体的情况下，激光闪光光解表明需要水分子才能通过分子内途径解锁光诱导的苯酚氧化。动力学监测包括具有不同光谱特性的两个快速相。第一阶段与苯酚到卟啉自由基阳离子的单电子转移以及多米诺骨牌的两个质子转移相关，导致质子从咪唑-苯酚对中脱出。第二阶段涉及将释放的质子传递至卟啉N ₄协调腔。我们的研究为光系统II的Tyr _Z / His ₁₉₀模型中的光诱导电子转移过程提供了空前的例子，证明了苯酚和咪唑质子都沿着同能路径运动。