微环境调控下芳烃选择性氧化制备酚的仿生催化体系研究

This project is proposed to explore the synthesis, catalytic properties and reaction mechanism of well designed bio-inspired catalysts with mild variable electronic effect, steric effect, synergetic effect and confined effect focused on selective oxidation of arene. Both mono- and heterometallic complexes supported by N-heterocyclic carbene and redox-active ligand will be designed to examine the unique effects that such cooperation can have on the reactivity of arene selective oxidation. Founctional supermolecule combined with enzyme active site models will be adopted to mimic the secondary coordination spheres, under which the relationship of catalytic active site, substrate and oxidant will also be carefully investigated with variable catalytic environment, electronic properties. Magnetic nano-particles loaded bio-inspired catalyst will be prepared to study the relationship between catalyst properties and reactivity under heterogeneous conditions.Carbon nano-tubes loaded heterogeneous catalyst will be prepared to investigate the effect of confinement on selective oxidation of arene. In addition, theoretical investigations into the electronic structure,intermediate, transition state of reactant and reactivity of prepared catalyst in this project will be studied using density functional theory (DFT) calculations. Isotopic tracing method will be used to help examine the reaction mechanism. This study was expected to acquire more information about the mechanism of selective catalytic oxidation of arene for phenols production and to facilitated the development of new iron-based bio-inspired catalyst.

针对芳烃选择性氧化制备酚类的基础科学问题，本项目拟以生物学研究成果为依托，在学科交叉领域对芳烃选择性氧化仿生催化体系的设计合成及催化机制等相关基础问题开展深入研究。通过具有氧化还原响应配体及氮杂环卡宾配体调控单核或异核的金属酶活性中心仿生催化剂，进而实现芳烃的选择性催化氧化，探讨催化剂分子设计的合理性及构效关系。通过功能化超分子配体模拟酶的二级配位结构，以调控催化剂活性中心的催化微环境、电子特性，揭示催化剂活性中心、底物以及氧化剂三组分之间的作用机制。以磁性纳米微粒或碳纳米管作为载体，揭示非均相下或纳米空间限域效应下，负载型仿生催化剂结构、电子特性与催化活性的关系规律。通过同位素示踪反应，DFT理论计算等手段揭示仿生催化氧化芳烃制备酚类的反应机理。可望从科学基础的角度揭示仿生催化体系设计合成的规律及催化反应机理，为开发新型芳烃选择性氧化催化剂提供新思路和理论依据。

在过去的四年里，我们以氢化酶功能为导向，基于电子效应、立体效应等，构建了一系列功能化仿生分子催化剂，并对其进行了全面表征，获得了其中17个新催化剂单晶分子结构。所制备的功能分子催化剂实现了仿生条件下选择性催化氧化，催化转移氢化，电化学催化还原质子制,等重要的催化特性。特别是我们发展了采用了氮杂环卡宾配体，构建功能化的具有不饱和配位结构的单铁及双铁核催化剂的方法。对多个仿生催化过程中催化活性中心、底物及氧化剂等三组分相互作用规律进行了阐明。我们通过密度泛函理论（DFT）计算与实验结果相结合探讨了配体结构特征、电子特性与催化剂基础性能的关系，进而提出了仿生催化反应性的影响规律，通过对反应中间产物，过渡态的能量和结构进行研究，提出了合理的反应机理。从化学仿生角度对氢化酶功能的作用机制获得了更多理解，为新型铁基仿生催化剂设计提供了基础和理论依据。