SusChEM: C-H Bond Electroactivation of Nonpolar Organic Substrates in Water: Enzyme-Mediated Reaction Pathways in Microemulsions

在水中进行有机反应，而不是在有机溶剂中进行，通过减少有害溶剂的使用和降低总体成本，提高了可持续性。不幸的是，大多数非极性有机分子不溶于水。大多数合成催化剂在水中的效果也很差，尤其是那些用于生产特殊产品（如药品）的催化剂。另外，酶是很好的生物催化剂，即使是在水中发生的反应。该项目旨在将合成铜聚合物催化剂与廉价的过氧化物酶结合起来，以加速非极性有机分子在水中的反应。电合成将在微乳液中进行，微乳液是油、水和低毒性、低成本洗涤剂的混合物，具有油和水的纳米级界面。这些乳剂通过将反应物运送到富水酶位点进行催化，提高了非极性反应物的溶解度和扩散速率。该项目的研究结果将为下一代可持续合成药物和特种化学品提供实用指导。除了研究生的高级培训外，该项目还将通过暑期研究活动为本科生和高中生提供培训机会。通过对K-12教师和学生的外展活动，组织化学合成的电化学酶催化讲习班。该提案旨在开发高温、可持续的生物电催化材料，并将其应用于水中氧对C-H键的电氧化。新的催化膜将通过合成铜聚合物催化剂和过氧化物酶类酶的逐层自组装来制备。这样的电催化系统将能够通过2e-还原铜催化剂进行氧活化的协同级联电催化，产生过氧化氢，过氧化氢进一步激活过氧化物酶来驱动非极性有机底物的氧化。铜催化剂与过氧化物酶的杂化膜也将通过化学交联稳定，进行高温电合成（90℃）。详细的动力学研究将在混合膜中进行，并对膜的组成进行微调，以优化铜催化剂上过氧化氢的生产速度和过氧化氢被过氧化物酶消耗的速度。在不同的纳米结构微乳中，研究并优化了两种类型的C-H在萘（sp2 C-H）和烷基苯（sp3 C-H）中的活性和选择性。在微乳液中，真正的绿色化学系统不仅解决了非极性底物的溶解度问题，而且为类似于中性pH水溶液的酶催化提供了明确的条件，将被开发出来。电化学动力学和光谱研究将用于理解扩散动力学和反应途径，以及非极性反应物的热力学激活障碍。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Running organic reactions in water rather than organic solvents increases sustainability by reducing the use of harmful solvents and lowering overall cost. Unfortunately, most nonpolar organic molecules do not dissolve in water. Most synthetic catalysts also work poorly in water, especially those aimed at producing specialty products such as pharmaceuticals. Alternatively, enzymes are excellent biocatalysts, even for reactions taking place in water. This project aims to combine synthetic copper polymer catalysts with inexpensive peroxidase enzymes to speed reactions of nonpolar organic molecules in water. Electrosynthesis will take place in microemulsions, which are mixtures of oil, water and low-toxicity, low-cost detergents, that feature nanoscale interfaces of oil and water. These emulsions improve the solubility and diffusion rate of nonpolar reactants by delivering reactants to water-rich enzyme sites for catalysis. The findings from this project will provide practical guidelines to next-generation sustainable synthesis of pharmaceutical and specialty chemicals. In addition to advanced training of graduate students, the project will offer training opportunities to undergraduate and high school students though summer research activities. Workshops on electrochemical enzyme catalysis for chemical synthesis will be organized through outreach activities for K-12 teachers and students. This proposal targets the development of high-temperature, sustainable bioelectrocatalytic materials and their applications to electrooxidation of C-H bonds by oxygen in water. New catalytic films will be fabricated via layer-by-layer self-assembly of synthetic Cu polymer catalysts and peroxidase-like enzymes. Such electrocatalytic systems will be capable of carrying out cooperative, cascade electrocatalysis of oxygen activation by Cu catalysts through 2e- reduction to produce hydrogen peroxide which further activates peroxidases to drive the oxidization of nonpolar organic substrates. The hybrid film of Cu catalysts and peroxidases will also be stabilized by chemical crosslinking to carry out high-temperature electrosynthesis ( 90 degrees C). Detailed kinetic studies will be analyzed in the hybrid films and the film composition will be fine-tuned to optimize the production rate of hydrogen peroxide on the Cu catalysts and its consumption rate by the peroxidases. The activity and selectivity of hybrid films will be investigated and optimized for two types of C-H activations in naphthyls (sp2 C-H) and alkylbenzenes (sp3 C-H) in various nanostructured microemulsions. True green chemistry systems in microemulsions that not only resolve the solubility issue of non-polar substrates but also provide well-defined conditions for enzymatic catalysts similar to aqueous solutions at neutral pH will be developed. Electrochemical kinetic and spectroscopic studies will be used to understand diffusion kinetics and reaction pathways, as well as the thermodynamic activation barriers for nonpolar reactants.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.