Synthesis, Reactivity and Catalysis of Novel Metallacarboranes

无机化学、生物无机化学和金属有机化学项目的这一奖项支持了密苏里大学罗拉分校的弗雷德里克·霍索恩教授的研究，他将依赖氧化还原的分子构象(纳米级)转化为具有为纳米机器提供动力的分子旋转马达的潜力。驱动运动由两个稳定的双-7，8-二羧基镍结构组成，它们具有形式的Ni(III)和Ni(IV)氧化态，通过单电子氧化还原过程相互转化，伴随着金属碳烷结构从顺相Ni(IV)到跨固相Ni(III)的可逆旋转变化(相对于笼状-C原子)。主要研究内容包括：(1)用2H和10B变温核磁共振法研究了双-7，8-二甲内酯类抗磁性化合物中取代二甲内酯配体围绕Ni、Fe和Co中心的旋转动力学。(2)核磁共振研究表明，取代马达的旋转使这些取代基在顺式构象中相互靠近，从而导致分子内配体间相互作用。(3)通过观察两个染料分子之间Forster共振能量转移(FRET)的变化，在溶液中演示了由氧化还原控制的这些取代基从变形体旋转到顺式关系而导致的具有Py取代基的可逆分子内准分子形成，以及(4)通过观察两个染料分子之间的Forster共振能量转移(FRET)的变化，证明了溶液中电机的旋转是受控的。(5)重复上述FRET实验，但通过连接基将马达分子锚定到溶胶凝胶表面。通过这种方式，可以演示浸没在液体、惰性气体或真空中的表面安装电机的操作。这种类型的成功纳米电机的工业和社会应用将使新一代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可以导致如下应用：(1)旋转式纳米阀的控制，(2)表面亲水性的控制，(3)表面的颜色或其他光学性质的控制，(4)催化中心活性的节流，(5)手性中心和开关之间的光学活性的机械转移，用于化学或电化学控制电子和光子。由于这一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，各级学生将获得广泛的经验，以便在学术界、政府或行业继续研究。

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.