基于有机磺酸配体的三维多孔金属有机框架的合成及其对CO2捕获和转化功能研究

It is highly imperative to develop carbon dioxide (CO2) capture and sequestration technologies. The architecture of conventional carboxylate-based metal-organic frameworks (MOFs) is well-defined with the prominent metal-carboxylate binding modes as well as the nonpolar porosity. The functionalization of carboxylate-based ligands usually requires sophisticated synthesis as well as significant sacrifice in porosity. The proposed research involves a mixed ligand system (organosulfoante and N-donor) to construct a rare class of organosulfonate-based MOFs possessing a high-polar permanent polarity and a three-dimensional (3-D) topology, thus achieving selective capture of CO2. In addition, the weak coordination nature of sulfonate groups allows for the missing metal-ligand connectivity and the coordinatively unsaturated metal sites in 3-D porous sulfonate-based MOFs. This phenomenon will catalytically convert CO2 to high-value chemicals, thus contributing to the development of CO2 capture and sequestration technologies. Taking advantage of the design of organosulfonate ligands and the mixed-ligand synthetic strategy, this proposal will construct a class of 3-D porous MOFs with organosulfonates as one of their struts. This study will provide a new platform for MOFs to be bifunctional solid-state crystalline materials for CO2 capture and catalytic conversion.

围绕当前发展二氧化碳（CO2）的捕获与封存技术的需求，针对传统羧酸类金属有机框架（MOF）中金属中心与羧酸的配位模式直接导致非极性孔道，而且在羧酸配体支链上修饰官能团存在繁琐、局限和降低孔隙率等问题，本项目拟采用有机磺酸配体与吡啶基配体的混合配体合成策略，构建一类具有永久高极性孔径且以有机磺酸配体为框架组成单元之一的三维网状MOF， 实现对CO2有选择性的捕获。本项目进一步利用有机磺酸配体与金属离子配位能力较弱的特点，引入金属中心与有机磺酸配体的缺失连接，实现配位环境不饱和的金属催化位点，通过催化反应将捕获的CO2转化合成高价值化学品，促进CO2的捕获与封存技术的发展。本项目集有机磺酸配体的设计合成和不饱和金属位点的催化研究为一体，构建一类以有机磺酸配体为框架组成单元之一的三维多孔MOF，为MOF作为双功能固相晶态材料进行捕获与催化转化CO2提供新平台。

围绕当前发展二氧化碳(CO2)的捕获与封存技术的需求，针对传统羧酸类金属有机框架（MOF）中存在的金属-羧基配位模式极性低、金属氧簇载流子迁移受限和碱性条件下结构易坍塌的三个问题，本项目从有机磺酸基三维网状MOF的构建、MOF中金属催化位点的卤族配位环境调控和MOF中碱性催化位点的修饰三个方面着手，为MOF进行捕获与转化CO2提供了良好的平台。首先，本项目创制了一类具有高极性孔径且以有机磺酸配体为框架组成单元之一的三维网状MOF，实现了将捕获的CO2催化转化至环碳酸酯和恶唑烷酮等高价值化学品。其次，本项目建立了基于金属卤族基元为无机节点的多孔MOF合成方法，结合理论计算和实验研究证实了金属卤族基元可在温和条件下活化CO2和H2O等小分子。第三，本项目发展了配体交换过程中原位拔氢构建活化的氮杂环卡宾修饰的MOF材料，强碱性的卡宾催化位点实现了在常温常压下CO2到甲醇的催化循环，探讨了基于MOF孔道限域效应的高选择性和高活性CO2催化还原机理。项目研究工作集MOF晶态材料的合成、修饰与CO2催化转化于一体，为MOF作为双功能固相晶态材料进行捕获与催化转化CO2提供了系统的实验研究和理论依据。