Selective Catalysts with an Inward Facing N-Heterocyclic Carbene

化学催化计划支持由Steven T教授领导的研究。纽约州立大学水牛城分校的Diver博士研究了一种新的大环N-杂环卡宾的合成。这种独特的大环设计具有多功能的配体指向内部的分子腔。N-杂环卡宾是强的亲核试剂，可用于催化碳-碳键的形成和作为过渡金属如钌的配体。该大环配体被设计成将过渡金属牢固地保持在其内部，其中发生选择性烯烃复分解反应。目前的钌卡宾催化剂显示出高的化学选择性（烯烃的偏好），但他们的一些关键的缺点是解决这项研究，包括分解，寿命的关键催化中间体，和选择性。 预期大环的限制性性质将限制分解途径，并将显示其化学反应物的尺寸选择性，这是烯烃复分解反应中未知类型的选择性。烯烃复分解是合成小分子、材料和能源应用的重要反应，用于大规模工业应用、药物合成以及药物发现的药物化学。在美国国家科学基金会化学部化学催化项目的支持下，Steven T. Diver和他的研究团队获得了新的化学催化剂，其应用范围广泛，基于占据腔体内部的金属。强亲核配体的基本性质进行了研究，在这个受控的环境。对新型钌卡宾催化剂的研究有望为可持续能源的应用提供更耐用的催化剂。例如，更高寿命的钌卡宾催化剂在生产经济上可行的生物柴油燃料中是关键的。外联部分力求通过高中生催化项目和K-12学生化学奖章日提高青年对化学作为一门实验科学的认识，依靠高中生和研究生领导活动。动力学实验是说明如何通过实验控制自然现象以及如何呈现数据的理想实验。催化剂，显示增加的活动，更长的寿命，更高的选择性是在需求和烷烃复分解，在本研究项目中审查的反应，被用作一种工具，使探针和染料的化学生物学。 钌卡宾的包封代表了通过限制双分子分解来控制选择性和改善催化剂稳定性的新方法。 这一概念可能被证明对其他金属催化应用广泛有用。

The Chemical Catalysis Program supports research led by Professor Steven T. Diver at the State University of New York (SUNY) at Buffalo on the synthesis of a new macrocyclic N-heterocyclic carbene. This unique macrocycle design features a versatile ligand pointing inward toward the inside of the molecular cavity. N-Heterocyclic carbenes are powerful nucleophiles useful both for catalytic carbon-carbon bond formation and as ligands for transition metals such as ruthenium. The macrocyclic ligand is designed to hold transition metals firmly in its interior where selective alkene metathesis reactions take place. Current ruthenium carbene catalysts display high chemoselectivity (preference for alkenes), but some of their key shortcomings are addressed by this research, including decomposition, lifetime of a key catalytic intermediate, and selectivity. The restrictive nature of the macrocycle is expected to limit decomposition pathways and will display size selectivity for its chemical reactants, an unknown type of selectivity in the alkene metathesis reaction. Alkene metathesis is an important reaction for the synthesis of small molecules, materials, and for energy applications and is used in large-scale industrial applications, the synthesis of pharmaceuticals, and in medicinal chemistry for drug discovery.With the support of the Chemical Catalysis Program in the Chemistry Division at the National Science Foundation, Professor Steven T. Diver and his research team access new chemical catalysts with a wide range of applications based on the metal occupying the interior of the cavity. Fundamental properties of the strong nucleophilic ligand are investigated in this controlled environment. The investigation of new ruthenium carbene catalysts is expected to produce more durable catalysts for applications in sustainable energy. For example, higher lifetime ruthenium carbene catalysts are critical in producing biodiesel fuel that are economically-viable. The outreach component seeks to increase awareness of chemistry as an experimental science to youth through a catalysis project for high school students and for K-12 students through a chemistry merit badge day, relying on high school students and graduate students to lead activities. Kinetics experiments are ideal to illustrate how natural phenomenon can be controlled through experiment and how data can be presented. Catalysts that display increased activities, longer lifetimes, and higher selectivities are in demand and alkane metathesis, the reaction under scrutiny in this research project, is used as a tool to make probes and dyes for chemical biology. Encapsulation of ruthenium carbenes represents a new approach to controlling selectivity and improving stability of a catalyst by limiting bimolecular decomposition. This concept may prove broadly useful to other metal-catalyzed applications.