Hemicarcerand ligands for the systematic investigation of sigma-alkane complexes

烷烃的选择性功能化是当代重要的一个领域，其动机是希望在有机合成和化学工业的原料中高效和有效地利用这些廉价和丰富的碳氢化合物。这些目标受到烷烃的化学惰性的阻碍，这些惰性是由碳-碳和碳-氢键所赋予的。通过可溶性过渡金属催化剂的作用，在克服这些限制方面取得了进展，尽管大规模的实际实施仍面临许多实质性的挑战。其中一个关键的障碍已经被证明是建立这些过程的基本机制化学：由于它们的瞬态和极易反应的性质，涉及烷烃活化过程的金属基中间体非常难以使用传统方法进行研究。这些信息构成了合理开发有用催化体系的重要前提知识。拟议的研究项目涉及开发一种前所未有的超分子方法，用于系统地研究过渡金属介导的烷烃活化，特别是难以捉摸的西格玛烷烃中间体。该方法需要制备和使用定义明确的大分子腔体和配体，它们通过将烷烃包封在大分子内部来促进和稳定过渡金属西格玛-烷烃配合物的形成。在这些超分子体系中包含烷烃有效地规避了与传统策略相关的有害问题，并允许有效地询问金属-烷烃相互作用。最终，这种方法将产生一个明确的基础化学体系，这将使人们对烷烃活化方法的理解发生重大变化。

The selective functionalisation of alkanes is an area of contemporary importance - motivated by the desire to make efficient and effective use of these inexpensive and abundant hydrocarbons in organic synthesis and as feedstocks for the chemical industry. Such objectives are encumbered by the chemical inertness of alkanes, conferred upon them by the strong constituent C-C and C-H bonds. Through the action of soluble transition metal catalysts, progress has been made in overcoming these limitations although many substantial challenges remain for large-scale practical implementation. One of the key stumbling blocks has proven to be establishing the fundamental mechanistic chemistry of these processes: encumbered by their transient and extremely reactive nature, metal-based intermediates involved in alkane activation processes are exceedingly difficult to investigate using conventional approaches. Such information constitutes vital prerequisite knowledge for the rational development of useful catalytic systems.The proposed research project involves the development of an unprecedented supramolecular approach for systematically investigating the transition metal mediated activation of alkanes, in particular elusive sigma-alkane intermediates. The approach entails the preparation and use of well-defined macromolecular cavitand ligands, which both promote and stabilise the formation of transition metal sigma-alkane complexes through encapsulation of the alkane within the interior of the macromolecule. The inclusion of the alkanes within these supramolecular systems effectively circumvents detrimental problems associated with conventional strategies and allows effective interrogation of the metal-alkane interaction. Ultimately, this approach will generate a definitive body of fundamental chemistry that will enable a step change in understanding of alkane activation methods.