Synthesis of Noble Metal-oxo Cluster-based Metal-Organic Frameworks and their Use in Heterogeneous Catalysis and Magnetism

本项目旨在系统地设计、合成、表征一系列新颖的多氧-贵金属(PONM)金属有机骨架，并对其催化性能和磁性进行研究。将利用整个类别的不同形状、大小和组成的离散多金属氧酸盐(POP)和多氧金酸盐(POA)来构建贵金属和混合贵金属基PONM-MOF。这种骨架材料的稳定性和组成将通过有机连接物的适当修饰或通过采用双二次构筑单元(SBU)策略来调节，其中POP/POA SBU将连接到其他类型的SBU，例如传统的POM、贵金属络合物或单一金属离子。该项目有望建立一个基于PONM-MOF的具有单或双催化中心的多相催化剂库，这些催化剂将被用作有机氧化、还原和C-C偶联反应的催化剂。所得到的PONM-MOF还可以作为牺牲模板来合成贵金属或混合贵金属基纳米颗粒@多孔炭复合材料，并将其作为光催化和电催化反应的催化剂。从PONM-MOF中制备贵金属基纳米粒子非常有吸引力，因为只需使用不同形状、大小和组成的PONM作为SBU，就可以调节纳米粒子的组成和尺寸。我们还打算利用以稀土为中心的POP作为SBU来分离Ln-POP-MOF，并将它们作为分子自旋量子比特进行研究，因为POP腔内的单个稀土离子表现出高度对称的配位环境(在LnPd12纳米立方体中为8配位立方，在LnPd15纳米星中为10配位五方配位)。Ln-POP在Ln-POP-MOF的刚性框架中具有良好的取向，通过增加/减少有机连接物的长度或使用柔性有机连接物可以微调各个自旋量子比特之间的相互作用。最近证明了POP-MOF的合成、结构和催化的原理证明(J.Am化学。SoC。2019、141、3385、−3389)。

This project aims at the systematic design, synthesis and characterization of a series of fundamentally novel polyoxo-noble-metalate (PONM)-based metal-organic frameworks (MOFs) and the investigation of their catalytic and magnetic properties. The entire class of discrete polyoxopalladates (POPs) and polyoxoaurates (POAs) of different shape, size and composition will be utilized to construct noble-metal and mixed noble-metal-based PONM-MOFs. The stability and composition of such framework materials will be tuned by suitable modification of the organic linkers, or by employing a dual secondary-building-unit (SBU) strategy, wherein the POP/POA SBUs will be linked to other types of SBUs such as conventional POMs, noble-metal complexes or single metal-ions. This project is expected to result in a library of PONM-MOF-based heterogeneous catalysts with either single or dual catalytic centers, which will be utilized as catalysts for organic oxidation, reduction, and C-C coupling reactions. The obtained PONM-MOFs can also be used as sacrificial templates to synthesize noble-metal- or mixed-noble-metal-based nanoparticles@porous-carbon composites, which will be tested as catalysts for photo- and electrocatalytic reactions. The formation of noble-metal-based nanoparticles from PONM-MOFs is highly attractive, because the composition and size of the nanoparticles can be tuned by simply using PONMs of different shape, size and composition as SBUs. We also aim to utilize lanthanide-centered POPs as SBUs to isolate Ln-POP-MOFs and to study them as molecular spin qubits, because the individual lanthanide ions inside the POP cavities exhibit highly symmetrical coordination environments (8-coordinated cubic in the LnPd12 nanocube or 10-coordinated pentagonal-prismatic in the LnPd15 nanostar). The Ln-POPs are well-oriented in the rigid framework of the Ln-POP-MOFs and the interactions of the individual spin qubits with each other can be fine-tuned by increasing/decreasing the length of the organic linkers or by using flexible organic linkers. The proof of principle for the synthesis, structure and catalysis of POP-MOFs was demonstrated recently (J. Am. Chem. Soc. 2019, 141, 3385−3389).