Boosting type-I ROS production of molecular photosensitizers using bridge-assisted superexchange coupling,Chemical Science

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Boosting type-I ROS production of molecular photosensitizers using bridge-assisted superexchange coupling
Chemical Science ( IF 7.6 ) Pub Date : 2024-09-10 , DOI: 10.1039/d4sc05345a
Lei Chen ₁ , Shirong Yan ₁ , Wu-Jie Guo ₁ , Lu Qiao ₁ , Xinyue Zhan ₁ , Bin Liu ₁ , Hui-Qing Peng ₁

Affiliation

Bridge-assisted superexchange coupling capable of long-range electron transfer proves to be effective for charge separation. However, the exploitation of this photochemical process in engineering reactive oxygen species (ROS) production remains unexplored. Herein, piperazine serves as a bridging unit to facilitate a cascade electron transfer from the electron donor site (CO) to the acceptor site (CN) within the COCN molecule, ultimately boosting the generation of superoxide radicals (O₂⁻˙) and hydroxyl radicals (˙OH). Experimental and theoretical studies elucidate that the long-range electron transfer is enabled by a superexchange interaction through the piperazine σ*-bridge, which leads to an effective generation of a radical ion pair CO⁺˙BCN⁻˙. The cationic radical CO⁺˙ can directly catalyze the oxidation of water, while the anionic radical CN⁻˙ transfers one electron to oxygen (O₂). Additionally, COCN has an excited triplet state characterized by a ³(π–π*) electronic configuration, which further promotes sequential electron transfer to O₂. These reactions enable the efficient production of ˙OH and O₂⁻˙, respectively, thus completing a cascade electron cycling process. Based on these findings, nanoparticles of COCN exhibit satisfying O₂⁻˙ and ˙OH production performance even under hypoxic environments and demonstrate potent photodynamic activity in addition to a notably high fluorescence quantum yield of 62.8%, rendering them promising candidates for cellular imaging and ablation assessments. This study contributes to the advancement of photosensitizers proficient in selectively generating ROS, offering valuable insights into the underlying mechanisms that govern ROS production.

中文翻译：

利用桥辅助超交换耦合促进分子光敏剂的 I 型 ROS 生产

能够进行长距离电子转移的桥辅助超级交换耦合被证明对于电荷分离是有效的。然而，这种光化学过程在工程活性氧（ROS）生产中的利用仍有待探索。其中，哌嗪作为桥连单元，促进COCN分子内从电子供体位点（CO）到受体位点（CN）的级联电子转移，最终促进超氧自由基（O ₂ ^- ˙）和羟基自由基的产生（哦）。实验和理论研究表明，长程电子转移是通过哌嗪σ*桥的超交换相互作用实现的，从而有效生成自由基离子对CO ⁺ ˙BCN ⁻ ˙。阳离子自由基CO ⁺ ˙ 可以直接催化水的氧化，而阴离子自由基CN ^- ˙ 将一个电子转移给氧（O ₂ ）。此外， COCN具有以³ (π–π*) 电子构型为特征的激发三重态，这进一步促进了电子向 O _{2 的}顺序转移。这些反应分别能够有效地产生 ˙OH 和 O ₂ ⁻ ˙，从而完成级联电子循环过程。基于这些发现， COCN纳米粒子即使在缺氧环境下也表现出令人满意的O ₂ ⁻ ˙和˙OH生产性能，并且除了具有高达62.8%的荧光量子产率之外，还表现出有效的光动力活性，使它们成为细胞成像和消融的有希望的候选者评估。这项研究有助于提高光敏剂选择性生成 ROS 的能力，为控制 ROS 产生的潜在机制提供有价值的见解。

更新日期：2024-09-10

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