祝贺赵子建同学的文章“Nature-Inspired Photocatalytic Azo Bond Cleavage with Red Light”在线发表于

Journal of the American Chemical Society（JACS），并被选为封面文章（Cover Paper）

工作简介：

        哺乳动物细胞中光氧化还原催化的新兴领域能够对大量生物过程进行时空调节。然而，低能可见光驱动的稳定共价键的选择性断裂仍然是一个巨大的挑战。在此，我们报道了市售染料（缩写为NMB⁺）的红光激发会导致水溶液和缺氧细胞中稳定偶氮键的催化裂解，因此是一种光递送药物或功能分子的方法。详细的机理研究表明，偶氮键断裂是由以前未知的连续双光子过程触发的。第一个光子产生三重激发态3 NMB^+*，其被电子供体还原猝灭以产生质子化的NMBH^•+。NMBH^•+发生歧化反应，生成初始NMB⁺和二电子还原的NMBH（即无色NMB，缩写为LNMB）。有趣的是，LNMB与所有四种偶氮底物形成电荷转移复合物，在红色区域具有强吸收带。第二个红色光子诱导电子从LNMB转移到偶氮基板，导致偶氮键断裂。本文报道的电荷转移复合物介导的双光子催化机制让人想起黄素依赖性天然光酶，其利用高能光子催化键断裂反应。红光驱动的光催化策略为生物正交偶氮键断裂提供了一种新的方法，用于药物或功能分子的光递送。

文章摘要：

        The emerging field of photoredox catalysis in mammalian cells enables spatiotemporal regulation of a wealth of biological processes. However, the selective cleavage of stable covalent bonds driven by low-energy visible light remains a great challenge. Herein, we report that red light excitation of a commercially available dye, abbreviated NMB⁺ , leads to catalytic cleavage of stable azo bonds in both aqueous solutions and hypoxic cells and hence a means to photodeliver drugs or functional molecules. Detailed mechanistic studies reveal that azo bond cleavage is triggered by a previously unknown consecutive two-photon process. The first photon generates a triplet excited state, ³ NMB^{+ *}, that is reductively quenched by an electron donor to generate a protonated NMBH^•+ . The NMBH^•+ undergoes a disproportionation reaction that yields the initial NMB⁺ and two-electron-reduced NMBH (i.e., leuco-NMB, abbreviated as LNMB). Interestingly, LNMB forms a charge transfer complex with all four azo substrates that possess an intense absorption band in the red region. A second red photon induces electron transfer from LNMB to the azo substrate, resulting in azo bond cleavage. The charge transfer complex mediated two-photon catalytic mechanism reported herein is reminiscent of the flavin-dependent natural photoenzyme that catalyzes bond cleavage reactions with high-energy photons. The red-light-driven photocatalytic strategy offers a new approach to bioorthogonal azo bond cleavage for photodelivery of drugs or functional molecules.    Zhao,Z . et. al. J. Am. Chem. Soc. 2023

封面描述：The convergence of two beams of red light functions akin to a knife and fork set, effectively piercing and splitting the nitrogen–nitrogen double bond of azo compounds upon interaction with a photocatalyst.

原文链接：

       https://www.x-mol.com/news/875131

祝贺我组赵子建同学荣获2022年国家奖学金!

祝贺赵子建同学的文章“Visible Light Generation of a Microsecond Long-Lived Potent Reducing Agent”在线发表于

Journal of the American Chemical Society（JACS），并被选为正面封面文章（Front Cover Paper），审稿人之一将其

高度评价为“A very significant advance on a conceptual and on a methodological (synthetic) level”。

工作简介：

       光敏剂分子的双重激发态结合了两个光子能量，可突破单个光子的能量限制，已被广泛研究证明其具有极强的氧化还原能力。这使得如脱卤反应、伯奇还原以及芳烃氧化等许多高需能反应在温和条件下（室温、可见光激发）成为可能。苝酰二亚胺型（PDI）光敏剂是最早发现也是研究最为广泛的具有连续可见光激发电子转移性质的一类光敏剂。然而前期的超快吸收光谱动力学研究表明，尽管²(PDI^•–)^*具有较强的还原能力，但其寿命只有约~160 ps。极短的光敏剂激发态寿命使其难以突破扩散限制将高能电子转移至底物，这极大地限制了利用连续光激发产生的超强还原剂的应用范围，一般只能应用于高底物浓度（mM~M）的有机合成中。

       复旦大学化学系胡可（点击查看介绍）课题组与北卡罗来纳大学教堂山分校Gerald Meyer教授（点击查看介绍）合作，将PDI光敏剂通过水杨酸基团锚定在介孔纳米晶二氧化锆（ZrO₂）（常被看作绝缘体）表面，可见光激发下，²(PDI^•–)^*的高能电子注入ZrO₂导带中，形成的电荷分离态ZrO₂(e^–)|PDI使高能电子的寿命延长至~53 μs。相比PDI^•–的激发态寿命，提升了近6个数量级。

文章简介：

       Photoexcitation of molecular radicals can produce strong reducing agents; however, the limited lifetimes of the doublet excited states preclude many applications. Herein, we propose and demonstrate a general strategy to translate a highly energetic electron from a doublet excited state to a ZrO₂ insulator, thereby increasing the lifetime by about 6 orders of magnitude while maintaining a reducing potential less than −2.4 V vs SCE. Specifically, red light excitation of a salicylic acid modified perylene diimide radical anion PDI•− anchored to a ZrO₂ insulator yields a ZrO₂(e⁻)|PDI charge separated state with an ∼10 μs lifetime in 23% yield. The ZrO₂(e⁻)s were shown to drive CO₂ → CO reduction with a Re catalyst present in micromolar concentrations. More broadly, this strategy provides new opportunities to reduce important reagents and catalysts at low concentrations through diffusional electron transfer.  Zhao, Z. et. al. J. Am. Chem. Soc. 2022

封面描述：

       Visible light excitation of a perylenediimide radical anion results in electron injection into a ZrO₂ insulator, yielding a potent reducing agent with a remarkable ~microsecond lifetime. The long-lived potent reducing agent provides new opportunities to reduce important reagents and catalysts present in low concentrations. 

原文链接：

       https://www.x-mol.com/news/754800

在2019年10月19日至21举行的能源化学与材料国际研讨会上，牛富双同学参与了大会的优秀墙报评比，

并在80份优秀的作品中脱颖而出，荣获优秀墙报奖。在此特向牛富双同学表示祝贺。