Synthesis, Reactivity and Catalysis of Novel Metallacarboranes

这个无机、生物无机和有机金属化学项目的奖项支持密苏里大学罗拉分校弗雷德里克·霍桑教授的研究，该研究将依赖氧化还原的分子构象（“纳米怪”）转化为具有为纳米机器提供动力潜力的分子旋转马达。驱动运动由两个稳定的双-7,8-二羰基镍结构组成，它们具有形式Ni（III）和Ni（IV）氧化态，通过单电子氧化还原过程相互转换，伴随着金属硼烷结构从顺面Ni（IV）到反面Ni（III）的可逆旋转变化（相对于笼- c原子）。本研究的重点是：(1)利用2H和10B变温核磁共振测量方法研究抗磁性共双-7,8-二碳核苷配合物中Ni、Fe和Co中心的取代二碳核苷配体旋转动力学。(2)核磁共振对分子内配体相互作用的解析，这种相互作用是由取代马达的旋转引起的，取代马达使这些取代基在顺流构象中彼此接近。(3)在溶液中证明了芘取代基的可逆分子内准分子形成是由这些取代基的氧化还原控制的由横切面到顺切面关系的旋转和反向旋转引起的。(4)通过观察附着在电机单独转子上的两个染料分子之间的福斯特共振能量转移（FRET）的变化，证明了溶液中电机的受控旋转。(5)重复上述FRET实验，但将马达分子通过连接基团锚定在溶胶-凝胶表面。通过这种方式，可以演示浸入液体，惰性气体或真空中的表面安装电机的操作。这种类型的纳米马达在工业和社会上的成功应用将使新一代的纳米分子和微型设备成为可能。将分子马达耦合到纳米器件上的应用包括：(1)旋转纳米阀的控制，(2)表面亲水性（亲水性/疏水性）的控制，(3)表面颜色或其他光学性质的控制，(4)催化位点活性的调节，(5)手性中心和开关之间光学活性的机械转移，用于电子和光子的化学或电化学控制。由于该领域的研究涉及分子设计、计算研究、合成、各种类型的光谱学、x射线衍射分子结构研究、电化学和纳米器件构建，各级学生将获得在学术界、政府或工业界继续研究的广泛经验。

This award in the Inorganic, Bioinorganic and Organometallic Chemistry program supports research by Professor Frederick Hawthorne at the Univesity of Missouri at Rolla to transform redox-dependent molecular conformers (a "nanowagger") into a molecular rotary motor with the potential for powering nanomachines. The driving motion consists of two stable bis-7,8-dicarbollynickel structures having formal Ni(III) and Ni(IV) oxidation states that are interconverted by single-electron redox processes accompanied by a reversible rotational change of the metallocarborane structure from cisoid Ni(IV) to transoid Ni(III) (with respect to cage-C atoms). The proposed research focuses on: (1) A study of the dynamics of substituted dicarbollide ligand rotation about Ni, Fe, and Co centers in diamagnetic commo-bis-7,8-dicarbollide complexes using both 2H and 10B variable temperature NMR measurements. (2) The NMR elucidation of intramolecular interligand interactions resulting from the rotation of substituted motors which brings these substituents into close proximity to one another in the cisoid conformation. (3) Demonstration in solution of reversible intramolecular excimer formation with pyrene substituents caused by redox-controlled rotation of these substituents from the transoid to the cisoid relationship and the reverse (4) Demonstration of controlled motor rotation in solution by the observation of changes in Forster resonance energy transfer (FRET) between two dye molecules each attached to a separate rotor of a motor. (5) Repetition of the FRET experiments described above, but with the motor molecule anchored by a linker group to a sol gel surface. In this way, the operation of surface-mounted motors immersed in liquids, inert gases or vacuum can be demonstrated. The industrial and societal applications of successful nanomotors of this type would enable a new generation of nanomolecular and micro devices. Coupling molecular motors to nanodevices could lead to applications including (1) the control of rotary nanovalves, (2) the control of the philicity of surfaces (hydrophilic / hydrophobic), (3) the control of the color or other optical properties of a surface, (4) the throttling of the activity of catalytic sites, (5) the mechanical transference of optical activity between chiral centers and switches for the chemical or electrochemical control of electrons and photons. Since research in this area involves molecular design, computational studies, syntheses, spectroscopy of all types, X-ray diffraction molecular structure studies, electrochemistry and nanodevice construction, students at all levels will receive broad experience for continued research in academia, government or industry.