Sun Ping-Ping, Chi Weijie, Kripalani Devesh R, Zhou Kun
Singapore Centre for 3D Printing, School of Mechanical and Aerospace Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798, Singapore.
Science, Mathematics and Technology Cluster, Singapore University of Technology and Design, 8 Somapah Road, Singapore 487372, Singapore.
Phys Chem Chem Phys. 2020 Sep 23;22(36):20721-20731. doi: 10.1039/d0cp03332d.
The use of organic photo-redox catalysts to initiate well-controlled photochemical reactions has aroused great interest. The development of visible light-driven photocatalytic reactions, which enable rapid and efficient synthesis of fine products, is highly desired from the perspective of being able to achieve low cost, good reversibility, and environmental friendliness. Herein, the organic photocatalytic cycle, with organic dithienophosphole (DTP) derivatives Ph-DTP and TPA-DTP as the photo-redox catalysts, and iodonium salt (Ar2I+) and ethyl 4-(dimethylamino)benzoate (EDB) as the respective acceptor and donor substrates, is fully analyzed by using density functional theory and dissociative electron transfer theory. We show that the strong redox potentials in the excited state as well as the sufficiently long-lived excited state of both DTP derivatives are a robust driving force for activating the electron acceptor Ar2I+ in the activation process. Moreover, the activation barriers of electron transfer are only 0.43-11.9 kcal mol-1 for the different activation pathways. During the deactivation process, the reaction energy profiles indicate that EDB plays a vital role in reducing DTPs˙+ to their initial states. Importantly, the activation barriers and rate constants in both activation and deactivation processes obtained in this study are better than those of classic Cu-based and metal-free Ph-PTZ-based photo-redox catalysts. The excellent performance of both DTP derivatives thus enables them to be highly efficient organic photo-redox catalysts.
使用有机光氧化还原催化剂引发可控的光化学反应引起了极大的兴趣。从能够实现低成本、良好的可逆性和环境友好性的角度来看，开发能够快速高效合成精细产品的可见光驱动光催化反应是非常必要的。在此，以有机二噻吩磷（DTP）衍生物Ph-DTP和TPA-DTP作为光氧化还原催化剂，碘鎓盐（Ar2I+）和4-（二甲基氨基）苯甲酸乙酯（EDB）分别作为受体和供体底物的有机光催化循环，通过密度泛函理论和离解电子转移理论进行了全面分析。我们表明，两种DTP衍生物在激发态的强氧化还原电位以及足够长寿命的激发态是在活化过程中激活电子受体Ar2I+的强大驱动力。此外，不同活化途径的电子转移活化能垒仅为0.43 - 11.9 kcal mol-1。在失活过程中，反应能量曲线表明EDB在将DTPs˙+还原到其初始状态中起着至关重要的作用。重要的是，本研究中获得的活化和失活过程中的活化能垒和速率常数均优于经典的铜基和无金属的Ph-PTZ基光氧化还原催化剂。因此，两种DTP衍生物的优异性能使其能够成为高效的有机光氧化还原催化剂。
