Artificial Enzymes: Development of Biomimetic Catalysts in Metal-Organic Frameworks

项目摘要/摘要 这项研究的目的是创建新的金属-有机骨架与FeS团簇模拟从 金属蛋白。在仿生催化剂中使用富含地球的生物相容金属，如铁，将 通过促进可用于人体样本的材料的开发来增进健康 生物标志物传感等应用。更具体地说，成功地合成了拟议的 材料将允许在人造酶中催化更复杂和更广泛的反应。 提出了两个相关的项目。首先，含有[2Fe：2S]团簇的仿生MOF 能够有效催化质子还原为分子氢的光敏剂将是 建造的。报告了几个[2Fe：2S]-MOF的例子；但是，它们尚未针对 高效的催化作用。使用最近推出的名为PCN-700的MOF，包含[2FE：2S]簇的连接子和 另一种含有光敏剂的化合物将以合成后的方式安装在PCN-700框架中，以产生 催化MOF。然后，这些[2Fe：2S]-MOF可以通过安装第三个连接基轻松地调整以提高催化效率 它的功能是控制MOF内的极触点。 其次，合成了含有[4Fe：4S]簇合物的MOF，并对其催化活性进行了评价。 成功地将[4Fe：4S]团簇包含在MOF中将扩大其催化和/或仿生潜力 通过利用四个铁位置提供的额外可用氧化态而不是较小的 FeS团簇。例如，可以进行更复杂的反应，例如需要四个或更多的反应 电子。此外，由于[4Fe：4S]团簇可以结合反应中间体(这一点还没有用 蛋白质中的[2Fe：2S]簇)，[4Fe：4S]-MOF可以用来研究没有 已经成功地利用生物系统或小分子进行了表征。提出了两种方法 用于合成[4Fe：4S]-MOF。首先，将合成自由的[4Fe：4S]团簇，每个团簇上带有-SCH3基团 菲尔。这些SCH3配体将与双官能团连接物4，4‘-联苯二硫酚交换以产生骨架， 在还原剂和酸的存在下。第二种合成方法涉及组装FeS团簇 同时用4，4‘-联苯二硫酚代替原方案中的HSCH3 设计用于合成游离的[4Fe：4S]团簇。 总体而言，这项工作的结果将推动利用FeS团簇的仿生催化剂领域的发展。这个 建议的[2Fe：2S]-MOF将优化催化活性，建议的[4Fe：4S]-MOF将是 这是此类催化剂中的第一个，从而引入了一类新的仿生催化剂。

PROJECT SUMMARY/ABSTRACT This research aims to create new metal-organic frameworks with FeS clusters modeled from metalloproteins. Using earth-abundant, biocompatible metals such as Fe in the biomimetic catalysts will enhance health by contributing to the development of materials that may be used on human samples for applications such as sensing biological markers. More specifically, successful synthesis of the proposed materials will allow for the catalysis of more complex and wide-ranging reactions in artificial enzymes. Two related projects are proposed. First, a biomimetic MOF containing [2Fe:2S] clusters and photosensitizers that can efficiently catalyzes the reduction of protons to molecular hydrogen will be constructed. A few examples of [2Fe:2S]-MOFs are reported; however, they have not been optimized for efficient catalysis. Using a recently presented MOF called PCN-700, a linker containing a [2Fe:2S] cluster and another containing a photosensitizer will be postsynthetically installed in the PCN-700 framework to yield a catalytic MOF. These [2Fe:2S]-MOFs can then be easily tuned for catalytic efficiency by installing a third linker that is functionalized to control polar contacts within the MOF. Second, MOFs containing [4Fe:4S] clusters will be synthesized and assessed for catalytic activity. Successful inclusion of [4Fe:4S] clusters in a MOF would expand the catalytic and/or biomimetic potential of MOFs by utilizing the additional available oxidation states afforded by the four Fe sites compared to smaller FeS clusters. For example, more complex reactions could be carried out, such as those requiring four or more electrons. Also, since [4Fe:4S] clusters can bind reaction intermediates (which has not been demonstrated with [2Fe:2S] clusters in a protein), the [4Fe:4S]-MOFs may be used to study reaction intermediates that have not been successfully characterized using the biological system or small molecules. Two approaches are proposed for synthesizing [4Fe:4S]-MOFs. First, free [4Fe:4S] clusters will be synthesized with -SCH3 groups on each Fe. These SCH3 ligands will be exchanged with the bifunctional linker 4,4’-biphenyldithiol to yield a framework, in the presence of reductant and acid. The second synthetic approach involves assembling the FeS clusters and the framework simultaneously by using 4,4’-biphenyldithiol instead of HSCH3 in the scheme originally designed for synthesizing free [4Fe:4S] clusters. Overall, the results of this work will advance the field of biomimetic catalysts using FeS clusters. The proposed [2Fe:2S]-MOFs will be optimized for catalytic activity, and the proposed [4Fe:4S]-MOFs would be the first of their kind, thereby introducing a new class of biomimetic catalysts.