Carbohydrate Receptors and Sensors

将研究两个相关主题：(1)碳水化合物在亲脂和亲水溶剂中的分子识别；(2)多功能催化在磷酸二酯水解中的作用。在第一个主题中，将研究分子中的两个分子内氢键在与具有两个氢键的受体的络合中既保留又断开的情况。多个能量分析将被用来探索分子内和分子间氢键的强度。与吡喃糖互补的双硼酸分子宿主将被制备成包含氧化还原金属离子的分子主体，该金属离子将改变络合葡萄糖的配位。具有不同配位球的金属离子的氧化还原电位的差异将成为葡萄糖在水介质中的电化学传感器的基础。在第二个主题中，我们将研究两个胍基在稳定磷酸二酯水解过渡态方面的双功能催化作用。研究了具有一般碱的三官能团催化和添加金属离子的四官能团催化。一种基于结合常数和过渡态类似物预测酶速率增强的方法将被应用于所提出的多功能催化。来自有机动力学项目的这笔资金支持德克萨斯大学奥斯汀分校的埃里克·V·安斯林教授的工作。两个主题将被追求：(1)碳水化合物的络合和(2)磷酸酯的多功能催化，这在生物系统中是重要的。在第一个项目中，将制备在水和有机溶剂中使葡萄糖等碳水化合物复杂化的分子。这些络合物的结构和稳定性将被确定。一种金属离子，如铁，将被结合到受体中，这将被电化学探测以确定葡萄糖是否络合。这将为水溶液中葡萄糖的检测提供实际应用。在第二个主题中，将制备一个使用两个有机基团作为磷酸二酯水解催化中心的分子。该体系将逐步扩展，包括一个基本官能团和一个金属离子。预计这种合成系统将模仿一种酶。

Two related topics will be studied: (1) Carbohydrate molecular recognition in lipophilic and hydrophilic solvents and (2) Multifunctional catalysis in phosphatediester hydrolysis. In the first topic, molecules will be investigated where two intramolecular hydrogen bonds are both retained and broken in complexation to a receptor with two hydrogen bonds. Multiple energetic analyses will be used to probe the strength of intra- and inter-molecular hydrogen bonds. Bis-boronic acid molecular hosts that are complementary to pyranoses will be prepared that incorporate a redox metal ion that will change coordination on complexing glucose. The difference in redox potential of the metal ion, with different coordination spheres, will be the basis of an electrochemical sensor for glucose in aqueous medium. In the second topic, bifunctional catalysis by two guanidinium groups in stabilization of the transition state of phosphatediester hydrolysis will be studied. Trifunctional catalysis with a general base and tetrafunctional catalysis with an added metal ion will be studied in the guanidinium system. A method for predicting enzyme rate enhancements based on binding constants and transition state analogs will be applied to the proposed multi-functional catalysis. %%% This grant from the Organic Dynamics Program supports the work of Professor Eric V. Anslyn at the University of Texas, Austin. Two topics will be pursed: (1) Complexation of carbohydrates and (2) Multifunctional catalysis of phosphatediesters, which are important in biological systems. In the first project, molecules that complex carbohydrates such as glucose in both water and organic solvents will be prepared. The structures of these complexes and their stabilities will be determined. A metal ion, such as an iron, will be incorporated into the receptor, which will be probed electrochemically to determine if glucose is complexed. This will lead to a practical application for the detection of glucose in aqueous solutions. In the second topic, a molecule will be prepared that uses two organic groups as catalytic centers for phosphatediester hydrolysis. This system will be expanded stepwise to include a basic functional group, and a metal ion. It is anticipated that this synthetic system will mimic an enzyme.