多级孔道结构功能配位聚合物的制备及选择性催化研究

Porous coordination polymers (PCPs) can be of a powerful tool for many important applications such as storage, separation, and catalysis due to the tunable shape and size selectivity of their pore apertures. Large pore aperture will make PCPs lose the unique selectivity; nevertheless, their small pore aperture inherently limits the diffusion of chemical species within PCPs, giving rise to low efficiency in real applications. To the best of our knowledge, the development of a suitable method to enhance the molecular diffusion within PCPs while preserving their selectivity remains a challenge. To solve this issue, we propose a facile encapsulation and etching strategy of nanoparticles (NPs) to craft mesopores with controlled size, shape and space distribution in MOFs. In addition, the hierarchical meso-PCPs should be obtained by flexible design of NPs encapsulation. Interestingly, we simultaneously incorporate two kinds of NPs in PCPs, where one kind of NPs is served as the catalytic active sites and another kind of NPs is used as the sacrificial template that is subsequently removed by simple etching, leaving mesopores inside the PCPs, thus further exploring their application in the field of selective catalysis. On the basis of our research work on design of the functional PCPs with hierarchical pore, we will explore the novel synthesis strategy of crafting the hierarchical pore with controlled size, shape and space distribution in PCPs, simultaneously grabbing the relationship between the hierarchical pore environment and high reaction efficiency as well as good selectivity in the field of catalysis. The project is expected to enhance diffusion of small species, to allow the large molecule reaction and to achieve good selectivity in the field of catalysis by adjusting the size, space-distribution and environment of hierarchical pore in PCPs.

多孔配位聚合物（PCPs）由于具有孔道尺寸和形状的可调节性在存储、分离及催化领域有着广泛的应用。介孔的PCPs虽然加速了分子的扩散，但失去了分子尺寸的选择性。微孔的PCPs保证了分子的选择性但限制了分子扩散速率，导致低效率。针对介孔和微孔PCPs在催化领域各自存在的局限性，本项目拟结合PCPs可控封装金属纳米颗粒（NPs）的技术及选择性刻蚀NPs的策略来构筑多级孔道结构PCPs，并拓展其在选择性催化领域的应用。在该制备策略中，其中一种NPs作为催化活性中心，另一种NPs作为牺牲模板用于构筑多级孔道。以设计和合成结构新颖的多级孔道结构功能性PCPs为研究重点，探索可控调节功能性PCPs多级孔道的尺寸、形状及空间位置的方法，阐明多级孔道结构PCPs的孔道微环境与催化反应效率、选择性之间的对应关系，最终实现多级孔道结构功能性PCPs复合材料在化工、医药及生物领域的选择性催化。

多孔配位聚合物（Porous Coordination Polymers, PCPs）由于具有孔道尺寸和形状的可调节性在存储、分离及催化领域有着广泛的应用。介孔的PCPs虽然加速了分子的扩散，但失去了分子尺寸的选择性。微孔的PCPs保证了分子尺寸的选择性，但限制了分子的扩散速率，导致低效率。针对介孔和微孔PCPs在催化领域存在的局限性，本研究结合可控封装金属纳米颗粒的技术，结合分子在孔道中运动受限的可调控性，实现了多官能团分子（二烯烃、二元醇、不饱和环氧等）的位置选择性催化。此外，通过封装纳米颗粒并结合选择性刻蚀纳米颗粒的策略，纳米颗粒在温和的溶剂条件下很容易被去除，制备了一系列多级孔PCPs，不仅增加了分子的扩散速率，还暴露了更多的活性位点，在Knoevenagel缩合-氢化级联反应中展现了优异的活性。更重要的是，通过化学刻蚀的醇解策略实现了羧酸类PCPs多级孔结构的制备，通过机理研究发现羧酸配体在醇的作用下反应生成脂，配体的去除有利于产生多级孔，残留下的金属离子可以转化为不饱和位点或者超小氧化物。通过反应时间、温度、醇碳链的长度及调节剂来调节羧酸类PCPs的孔道尺寸以及孔体积变化，同时还保留了PCPs的形貌、微孔及晶体结构。此外，得到了一系列多级孔功能化的PCPs材料兼具多级孔和更多的路易斯活性位点，导致在路易斯催化反应中表现出优异的催化活性。多级孔PCPs的制备策略及催化应用探索的研究，为其实现化工、医药及生物领域的选择性催化提供了材料支撑和理论指导。