CAREER: Binucleating Bis(pyrazolyl)alkanes for Tractable Bimetallic Polymerization

在化学系化学催化项目的支持下，休斯顿大学的Robert Comito正在开发用于合成生物可降解聚合物的双金属催化剂。目前，大多数合成塑料和弹性体都是由石化产品制备的，既不能生物降解，也不能生物相容性。尽管一些可生物降解聚合物已经被开发出来作为石化产品的替代品，但它们的合成需要不同于石化产品的催化剂，这一点尚不清楚。Comito研究计划的目标是通过关注多个金属位点之间的合作，开发一种新的生物可降解聚合物合成催化剂平台。这些研究的重点是寻找新的催化剂，以制备具有新结构、新物理性质和改进性能的可生物降解聚合物。这些活动被进一步用于培养有机金属化学、催化和聚合物合成领域的多样化学生群体，重点是包括本科生、第一代学者和STEM（科学、技术、工程和数学）学科中代表性不足的群体。此外，通过这项研究项目产生的技术知识正在转化为公开可用的教育材料，用于向研究生教授机械分析，向本科生教授反应机制。在这个奖项下，Robert Comito和他的研究团队正在开发两种主要金属基团的近端配位配体，用于协同催化，以实现可生物降解聚合物的可控合成。本研究计划的假设基础是，主族金属催化酯类和碳酸盐的聚合不可避免地涉及多金属机制。考虑到醇酮链末端的金属桥接配位和单体原料的双功能插入是聚合过程中链生长的基本特征，Comito和他的团队正在评估相邻催化金属位点的取向、距离和取代，以确定主基团催化聚合产生独特聚合物结构的控制机制特征。Comito博士将这些机械分析的技巧应用到教学中，正在制作拖放式教材，以数字格式改进反应机制的教学。他还编写了关于控制实验的教学材料，这是一类对理解科学机制至关重要的实验，但很少在课堂上教授。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。

With the support of the Chemical Catalysis Program in the Division of Chemistry, Robert Comito of the University of Houston is developing bimetallic catalysts for the synthesis of biodegradable polymers. Currently, most synthetic plastics and elastomers are prepared from petrochemicals and are neither biodegradable nor biocompatible. Although some biodegradable polymers have been developed as replacements for petrochemical ones, their synthesis requires different catalysts than those used for petrochemicals that are not well understood. The goal of the Comito research program is to develop a new platform of catalysts for biodegradable polymer synthesis by focusing on the cooperation between multiple metal sites. These studies are focused on finding new catalysts that can be tuned to prepare biodegradable polymers with novel structures, new physical properties, and improved performance. These activities are further being used to train a diverse group of students in organometallic chemistry, catalysis, and polymer synthesis with emphasis on the inclusion of undergraduates, first-generation scholars, and underrepresented groups in STEM (science, technology, engineering and mathematics) disciplines. Moreover, the technical knowledge generated through this research program is being converted into publicly available educational materials for teaching mechanistic analysis to graduate students and reaction mechanisms to undergraduates.Under this award, Robert Comito and his research team are developing ligands for the proximal coordination of two main group metals for cooperative catalysis toward the controllable synthesis of biodegradable polymers. The hypothesis underlying this research program is that the catalytic polymerization of esters and carbonates by main group metals inevitably involves multi-metallic mechanisms. Considering that metal-bridging coordination of an alkoxide chain end and bifunctional insertion of the monomer feedstock are essential features of chain growth during polymerization, Comito and his group are evaluating the orientation, distance, and substitution of adjacent catalytic metal sites to identify the controlling mechanistic features of main-group catalyzed polymerization that produce unique polymer structures. Applying these skills in mechanistic analysis toward teaching, Dr. Comito is generating drag-and-drop teaching materials that will improve the instruction of reaction mechanisms in a digital format. He is also generating pedagogical materials on control experiments, a class of experiments essential toward understanding mechanisms in science but which are rarely taught in the classroom.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.