Exploratory Syntheses of Borometallic Molecular Wheels and Borospherenes

非技术摘要：本EAGER提案旨在通过液相激光烧蚀的方法，验证新型固体形式硼基纳米团簇的原理合成。如果概念验证工作取得成功，可能会发现使用湿化学的更好的合成路线，以提高合成收率。开发有效的大规模合成这些新型硼纳米结构的方法将代表材料科学的重大进步。块状的硼纳米结构将提供具有潜在有趣的电子、磁性和催化性能的新型材料。EAGER项目还将为本科生和研究生提供跨学科的研究培训。技术摘要：在过去的十年中，对尺寸选择硼团簇的研究导致了从平面团簇到硼烯和硼球烯的各种有趣的纳米结构。硼苯（或原子薄硼层）是近年来在银衬底上合成的一类新的二维材料。这个EAGER项目旨在探索固体形式硼球烯（全硼笼簇）的体合成，以及过渡金属中心硼环型簇，M©Bn (n = 8-10)，这是芳香硼金属分子轮。由于硼的电子缺陷性质，硼金属团簇和硼球状体的边缘或表面原子具有空的2p轨道，并且有望与路易斯碱类型的配体（如酰胺或磷化氢）发生反应，这些配体将用于保护团簇。M©Bn型团簇和硼球将通过激光烧蚀合适的硼/金属复合材料或纯硼靶在含有合适配体的溶液中产生。配体将协调到新生的硼纳米团簇，使其分离和随后的结构和性质表征。激光烧蚀也可以在溶液外进行，这样就可以捕获新生的簇。该合成方法将采用物理和化学相结合的方法，不像富勒烯合成方法完全是物理方法（碳弧在He中）。

Non-Technical Summary: This EAGER proposal is aimed at proof-of-principle syntheses of novel boron-based nanoclusters in solid forms using laser ablation in the liquid phase. If the prove-of-concept efforts are successful, better synthetic route using wet chemistry may be found to improve the synthetic yields. Development of effective large-scale synthetic methods of these novel boron nanostructures would represent significant advances in materials science. The boron nanostructures in bulk form will provide new classes of materials with potentially interesting electronic, magnetic, and catalytic properties. The EAGER project will also provide research training for undergraduate and graduate students across disciplines. Technical Summary: Studies on size-selected boron clusters over the past decade have led to a variety of interesting nanostructures from planar clusters to borophenes and borospherenes. Borophenes (or atomic thin boron layers) have recently been synthesized on silver substrates as a new class of 2D materials. This EAGER project seeks to explore bulk syntheses in solid forms of borospherenes (all-boron cage clusters), as well as transition metal centered boron ring type clusters, M©Bn (n = 8-10), which are aromatic borometallic molecular wheels. Due to the electron deficient nature of boron, the edge or surface atoms of the borometallic clusters and borospherenes have empty 2p orbitals and are expected to be reactive with Lewis base types of ligands, such as amides or phosphines, which will be used to protect the clusters. The M©Bn type clusters and borospherenes will be produced by laser ablation of appropriate boron/metal composite or pure boron targets in solutions, which contain the appropriate ligands. The ligands will coordinate to the nascent boron nanoclusters to allow their isolation and subsequent structural and property characterization. The laser ablation can also take place outside the solution, which can then capture the nascent clusters. The synthetic method will be a combination of physical and chemical approach, unlike the fullerene synthetic method, which is a completely physical method (carbon arc in He).