Gao Hui, Tang Yang, Liu Songtao, He Cheng, Li Huaqing, Zhao Liang, Duan Chunying
State Key Laboratory of Fine Chemicals, Frontier Science Center for Smart Materials, Dalian University of Technology, Dalian 116024, P. R. China.
State Key Laboratory of Coordination Chemistry, Nanjing University, Nanjing 210093, P. R. China.
ACS Appl Mater Interfaces. 2024 Jul 24;16(29):37896-37905. doi: 10.1021/acsami.4c05017. Epub 2024 Jul 15.
The selective oxidation of alcohols into aldehydes is a basic and significant procedure, with great potential for scientific research and industrial applications. However, as an important factor in the C(sp)-H activation process, high selectivity is generally difficult to achieve due to the fact that the more easily activated properties of aldehydes are compared to alcohols. Herein, by the ingenious decoration of eosin Y into a Zr-based metal-organic framework (MOF-808), EY@MOF-808 was prepared as a selectivity regulator for the aerobic oxidation of the benzyl alcohols into corresponding aldehydes, possessing applicability for the benzylic alcohols with various substituents. By anchoring eosin Y on ZrO(OH) clusters of MOF-808 and maintaining open metal nodes with selective binding effects, the benzyl alcohol substrates were selectively coordinated to the unsaturated metal clusters adjacent to eosin Y, which ensured that the excited eosin Y rapidly activated substrates to generate carbon radicals by the hydrogen atom transfer (HAT) process. The rapid electron transfer (ET) simultaneously produced reactive oxygen species (O) and then a combination of both to further promote the generation of benzaldehydes. The weak interaction of benzaldehydes with the skeleton allowed it to dissociate rapidly, thus preventing overoxidation. Under the catalysis of EY@MOF-808, the selectivity of various benzaldehydes was more than 99%. In contrast, eosin Y gave only benzoic acid products under the same conditions, which demonstrated the superiority of regulatory selectivity of EY@MOF-808. Taking advantage of the heterogeneity of the MOF, EY@MOF-808 was recycled four times without a decrease in its selectivity and avoided the quenching effect of eosin Y. The organic functional units postdecorated MOF-based photocatalyst strategy exhibits a promising new perspective approach to sustainably regulating the selectivity of inert oxidation.
醇选择性氧化为醛是一个基础且重要的过程，在科学研究和工业应用中具有巨大潜力。然而，作为C(sp)-H活化过程中的一个重要因素，由于醛比醇更容易被活化，通常难以实现高选择性。在此，通过将曙红Y巧妙地修饰到基于Zr的金属有机框架（MOF-808）中，制备了EY@MOF-808作为将苄醇有氧氧化为相应醛的选择性调节剂，对具有各种取代基的苄醇均适用。通过将曙红Y锚定在MOF-808的ZrO(OH)簇上并保持具有选择性结合作用的开放金属节点，苄醇底物选择性地与曙红Y相邻的不饱和金属簇配位，这确保了激发态的曙红Y通过氢原子转移（HAT）过程迅速活化底物以产生碳自由基。快速电子转移（ET）同时产生活性氧（O），然后两者结合进一步促进苯甲醛的生成。苯甲醛与骨架的弱相互作用使其能够迅速解离，从而防止过度氧化。在EY@MOF-808的催化下，各种苯甲醛的选择性均超过99%。相比之下，在相同条件下曙红Y仅生成苯甲酸产物，这证明了EY@MOF-808在调节选择性方面的优越性。利用MOF的异质性，EY@MOF-808可循环使用四次，其选择性无下降，并且避免了曙红Y的猝灭效应。后修饰MOF基光催化剂策略中的有机功能单元展现出一种可持续调节惰性氧化选择性的有前景的新视角方法。
