Redox-Active Metal-Organic Frameworks: Novel Entatic State Catalysts?

应开发具有氧化还原活性的多孔金属有机骨架(MOF)，该骨架由芳香族N-给体配体(例如，吡唑基或三氮唑基)和开壳型3D过渡金属离子构成。以往的研究表明，杂环芳香族N-供体的使用大大提高了MOF化合物的水解稳定性，这是催化氧化过程的必要条件。将特别注意将多核过渡金属簇嵌入刚性三维配位框架(“内生态催化剂”)的具体优点。因此，应比较固体MOF催化剂的光谱和催化性能，特别强调气相反应。量子化学研究将解决多核团簇中电子耦合金属位置的不同氧化状态，以及它们在催化氧化或氧化循环中的作用。应用基于广义梯度近似(GGA)和混合泛函的密度泛函理论(DFT)研究了MOF的基态和激发态性质。将特别注意振动和UV/Vis光谱等重要性质以及设想的化合物的氧化还原行为。

Porous, redox-active metal-organic frameworks (MOFs) shall be developed which are constructed from aromatic N-donor ligands (e.g. pyrazolate or triazolate moieties) and openshell 3d transition metal ions. Previous investigations have demonstrated that the use of heterocyclic aromatic N-donors leads to greatly enhanced hydrolytic stability of the MOF compounds, which is a necessary condition for catalytic oxidation processes. Particular attention will be addressed to the specific advantages of embedding a multinuclear transition metal cluster into a rigid 3D coordination framework (“entatic state catalyst”). Thus, the spectroscopic and catalytic properties of solid MOF catalysts shall be compared with special emphasis laid upon gas phase reactions. Quantum chemical investigations will address different oxidation states of the electronically coupled metal sites in multinuclear clusters, and their role in catalytic oxidation or oxygenation cycles. Density functional theory (DFT) based on general gradient approximation (GGA) and hybrid functionals is applied to investigate ground and excited state properties of the MOFs. Special attention will be paid to important properties like vibrational and UV/VIS spectroscopy as well as to the redox behaviour of the envisaged compounds.