Department of Chemistry and Shenzhen Grubbs Institute, Southern University of Science and Technology, Shenzhen, Guangdong 518055, China.
School of Chemistry, South China Normal University, Guangzhou, Guangdong 510006, China.
Dalton Trans. 2023 Jul 4;52(26):9121-9130. doi: 10.1039/d3dt01403g.
Selective oxidation of alcohols to aldehydes is an industrially significant chemical transformation. Herein, we report a mixed-valence polyoxovanadate-based metal-organic framework (MOF), (Hbix){[Cd(bix)][VIV8VV7OCl]}·3HO (V-Cd-MOF), for catalyzing the additive-free oxidation of a series of aromatic alcohols with high selectivity and in nearly quantitative yield to the corresponding aldehydes with O as the oxidant. Experimental results, corroborated with density functional theory calculations, indicate that it is the synergistic operation of the dual active sites of the V-O-V building units in the polyoxovanadate cluster that is responsible for the excellent catalytic performance observed: on the one hand, the exposed and readily accessible reduced V site is believed to activate O, resulting in a reactive oxygen species for the subsequent activation and breaking of the substrate's C-H bond. On the other hand, the V site coordinates with the alcoholic O atom to facilitate the cleavage of the O-H bond. The catalyst can be recycled by centrifugation and re-used at least five times with uncompromised performance. To our knowledge, V-Cd-MOF represents the first example of a polyoxometalate-based MOF catalyst for additive-free selective oxidation of alcohol to aldehyde with O as an oxidant.
醇的选择性氧化是一种具有重要工业意义的化学反应。在此，我们报道了一种基于混合价多金属氧酸盐的金属有机骨架（MOF），（Hbix）{[Cd（bix）][VIVO8VV7OCl]}·3HO（V-Cd-MOF），可用于在无添加剂的条件下催化一系列芳香醇的氧化，具有高选择性，几乎定量产率得到相应的醛，氧化剂为 O。实验结果与密度泛函理论计算相吻合，表明是多金属氧酸盐簇中 V-O-V 构建单元的双活性位的协同作用导致了观察到的优异催化性能：一方面，暴露的、易于接近的还原 V 位被认为可以激活 O，从而产生活性氧物种，随后进一步激活并断裂底物的 C-H 键。另一方面，V 位与醇的 O 原子配位，有利于 O-H 键的断裂。通过离心可以回收催化剂，至少可以重复使用五次而不影响性能。据我们所知，V-Cd-MOF 代表了首例以多金属氧酸盐为基础的 MOF 催化剂，可在无添加剂的条件下，以 O 为氧化剂，选择性地将醇氧化为醛。
