Fertig Alex A, Rabbani S M Gulam, Koch Melissa D, Brennessel William W, Miró Pere, Matson Ellen M
Department of Chemistry, University of Rochester, Rochester, NY 14627, USA.
Nanoscale. 2021 Mar 28;13(12):6162-6173. doi: 10.1039/d0nr09201k. Epub 2021 Mar 18.
We report a rare example of the direct alkylation of the surface of a plenary polyoxometalate cluster by leveraging the increased nucleophilicity of vanadium oxide assemblies. Addition of methyl trifluoromethylsulfonate (MeOTf) to the parent polyoxovanadate cluster, [VO(TRIOL)] (TRIOL = tris(hydroxymethyl)methane; R = Me, NO) results in functionalisation of one or two bridging oxide ligands of the cluster core to generate [VO(OMe)(TRIOL)] and [VO(OMe)(TRIOL)], respectively. Comparison of the electronic absorption spectra of the functionalised and unfunctionalised derivatives indicates the decreased overall charge of the complex results in a decrease in the energy required for ligand to metal charge transfer events to occur, while simultaneously mitigating the inductive effects imposed by the capping TRIOL ligand. Electrochemical analysis of the family of organofunctionalised polyoxovanadate clusters reveals the relationship of ligand environment and the redox properties of the cluster core: increased organofunctionalisation of the surface of the vanadium oxide assembly translates to anodic shifts in the reduction events of the Lindqvist ion. Overall, this work provides insight into the electronic effects induced upon atomically precise modifications to the surface structure of nanoscopic, redox-active metal oxide assemblies.
我们报道了一个罕见的例子，即通过利用氧化钒组装体亲核性的增强，实现了全同多金属氧酸盐簇表面的直接烷基化。将三氟甲磺酸甲酯（MeOTf）添加到母体聚氧钒酸盐簇[VO(TRIOL)]（TRIOL = 三（羟甲基）甲烷；R = Me，NO）中，会导致簇核心的一个或两个桥连氧化物配体发生官能化，分别生成[VO(OMe)(TRIOL)]和[VO(OMe)(TRIOL)]。官能化和未官能化衍生物的电子吸收光谱比较表明，配合物整体电荷的降低导致配体到金属电荷转移事件发生所需能量的降低，同时减轻了封端TRIOL配体施加的诱导效应。对有机官能化聚氧钒酸盐簇家族的电化学分析揭示了配体环境与簇核心氧化还原性质之间的关系：氧化钒组装体表面有机官能化程度的增加导致Lindqvist离子还原事件的阳极位移。总的来说，这项工作为对纳米级氧化还原活性金属氧化物组装体表面结构进行原子精确修饰时所诱导的电子效应提供了深入了解。
