Earth abundant element catalysts - Fe, B, Al not feeble compounds for polymer production and conversion of carbon dioxide

新催化剂的发现是以环保方式生产能源、化学品和材料的关键。我们的研究计划侧重于在催化剂的中心使用地球上丰富的元素，以铝、铁和硼为目标。我们将使用我们的催化剂从二氧化碳中制造新的分子，并制备可再生和可降解的聚合物。研究地球上丰富的催化元素是具有挑战性的，但与贵金属相比，它使化学家能够获得机械上不同的反应，因此我们的一些发现将是不可预见的。我们最近发现了一种无金属的方法，通过与合适的环氧化物反应，将二氧化碳转化为环状碳酸盐或聚碳酸酯产品。这种工作是在大气压力下进行的，每小时翻转频率超过1200次。初步结果表明，我们可以利用硼烷固有的反应活性，在一锅连续串联催化过程中产生功能聚合物，我们将在未来5年内进一步探索这些反应。我们还将开发基于铝和铁配位化合物的新型均相催化剂。铁化合物本身将表现出依赖于氧化态的反应活性，并且将二茂铁（一种铁分子）引入铝和硼化合物中将导致氧化还原可切换的催化剂系统，其中不同的催化行为可以开启和关闭。开关也可能影响物理性质，如在表面上的溶解度和吸附，这可以很容易地从产物中分离出均相催化剂。这种催化剂行为的结合可以减少使用二氧化碳的商业过程所需的时间。在我们的工作中，使用二氧化碳与环氧化物和氮化吡啶反应的新催化剂，包括那些来自生物原料（如萜烯，氨基酸）的催化剂，我们将通过原位红外光谱反应监测，紫外-可见滴定（在铁的情况下）和多核核磁共振研究（包括硼和铝），对我们的催化剂系统有一个基本的了解。世界范围内的研究人员对环氧化物的氮类似物，氮嘧啶的研究程度要小得多，并且有可能从可再生氨基醇中制备。我们预计，我们的硼和铝催化剂体系将在氮吡啶和二氧化碳的反应中比更常见的过渡金属催化剂更活跃。此外，在这些反应中扩大共试剂的范围，使叠氮嘧啶更广泛地使用或在串联过程中实现聚合物改性是至关重要的。除了基础科学发现外，该研究项目还将吸引和培养下一代绿色化学研究人员，他们将对加拿大的科学、技术和教育产生重大影响。

Discovery of new catalysts is key to the production of energy, chemicals and materials in an environmentally-friendly way. Our research program focuses on using earth-abundant elements at the centre of our catalysts by targeting aluminum, iron and boron. We will use our catalysts to build new molecules from carbon dioxide, and to prepare renewable and degradable polymers. Studying earth-abundant elements in catalysis is challenging but allows chemists to access mechanistically distinct reactions compared with precious metals, and so some of our discoveries will be unforeseen. We recently discovered a metal-free process for converting carbon dioxide to either cyclic carbonate or polycarbonate products upon reaction with suitable epoxides. This works at atmospheric pressure and turnover frequencies in excess of 1200 per hour have been observed. Preliminary results show that we can exploit the inherent reactivity of boranes to yield functional polymers in a one-pot, sequential tandem catalytic process, and we will explore these reactions further during the next 5 years. We will also develop new homogeneous catalysts based on aluminum and iron coordination compounds. The iron compounds themselves will show oxidation state dependent reactivity, and introduction of ferrocene (an iron molecule) into aluminum and boron compounds will lead to redox-switchable catalyst systems where different catalytic behaviours can be turned on and off. The switching may also affect physical properties such as solubility and adsorption on surfaces, which could be used to easily separate homogeneous catalysts from products. Incorporation of such catalyst behaviours could decrease the time required for commercial processes that use carbon dioxide. In our work using new catalysts for the reactions of carbon dioxide with epoxides and aziridines, including those derived from biological feedstocks (e.g. terpenes, amino acids), we will develop a fundamental understanding of our catalyst systems through in situ IR spectroscopic reaction monitoring, UV-Vis titrations (in the case of iron), and multinuclear NMR studies (including boron and aluminum). The nitrogen-analogs of epoxides, aziridines, have been studied to a much lesser extent by researchers worldwide, and can potentially be prepared from renewable amino alcohols. We anticipate that our boron and aluminum catalyst systems will be more active in the reactions of aziridines and carbon dioxide compared with more commonly studied transition metal catalysts. Furthermore, expanding the scope of co-reagents in these reactions so aziridines are more widely employed or polymer modification can be achieved in a tandem process is critically important. In addition to fundamental scientific discoveries, this research program will attract and train the next generation of green chemistry researchers who will make a considerable impact in Canadian science, technology and education.