NSF Young Investigator: Coordination Chemistry of Redox-Active Tetradentate Hemilabile Ligands

提案：9357099 PI：米尔金配位化学将为西北大学米尔金教授的研究课题；他将在美国国家科学基金会无机、生物无机和有机金属化学项目的青年研究员奖的支持下进行这项研究。他的一个研究领域将是“半可溶”复合物的合成和性质。这些是具有氧化活性位点的配体的配合物，在还原状态下是四齿的，在氧化状态下是双齿的。因此，当中心金属离子为Rh(I)时，当配体处于还原态时，它是惰性的，但当处于氧化态时，它应该是烯烃加氢的有效催化剂。该方案为氧化还原可切换催化提供了一个入口。另一个研究领域涉及自组装单层（SAMS）。具体方案包括使用衍生化金属卟啉作为表面层，并且，特别是，其中配体设计导致配体的平面垂直于表面；这将导致配体平面的平行取向，这有望赋予这些SAMS不同寻常的电催化性能。“分子装置”这一新生概念在化学领域提供了许多机会。一种方法是基于传统的配位化学，其中一个金属离子在几个位置与另一个分子（称为配体）结合。一个有趣的进展是，在配体中加入了提供电子的能力，因为这样做后，配体与金属离子的结合就会发生根本性的变化。这种变化可以区分金属离子的催化活性和非催化活性，因此人们有了一种方法来切换催化活性和关闭催化活性。另一个发展是设计配体，使其自身吸附到表面形成高度定向的单层。如果表面是一个电极，那么这种单层可以赋予电极独特的反应性。测试和发展这些想法的实验构成了本项目研究的核心。

Proposal: 9357099 PI: Mirkin Coordination chemistry will be the subject of investigation for Professor Mirkin of Northwestern University; he will conduct this research with support in the form of an NSF Young Investigator Award from the Inorganic, Bioinorganic, and Organometallic Chemistry Program. One area of his research will be in the synthesis and properties of "hemilabile" complexes. These are complexes of ligands that bear a redox-active site, are tetradentate in the reduced state and bidentate in the oxidized state. When the central metal ion is Rh(I) it is thus expected to be inert when the ligand is in the reduced state, but when in the oxidized state it should be an effective catalyst for olefin hydrogenation. This scheme provides an entree into redox-switchable catalysis. Another area of research deals with self- assembled monolayers (SAMS). Specific plans include using derivatized metalloporphyrazines as the surface layer, and, in particular, where the ligand design leads to the plane of the ligand being perpendicular to the surface; this will lead to a parallel orientation of the ligand planes, which is expected to confer unusual electrocatalytic properties on these SAMS. %%% The nascent concept of "molcular devices" poses many opportunities in chemistry. One approach is based on traditional coordination chemistry, where a metal ion is bound to another molecule (called a ligand) at several sites. An interesting development is to build into the ligand the ability to donate an electron, for when this is done the binding of the ligand to the metal ion can change radically. This change can make the difference between a metal ion that is catalytic and one that is not, and thus one has the elements of a method to switch catalytic activity one and off. Another development is to design ligands that will cause themselves to adsorb to a surface to form a highly oriented monolayer. If the surface is an electrode, then such a monolayer could c onfer unique reactivity to the electrode. Experiments to test and develop these ideas form the core of the research to be conducted in this project.