Thermal and Photochemical Reactions of Transition Metal Complexes of the Nitrogen Oxides and other Small Molecules

美国国家科学基金会无机化学、生物无机化学和金属有机化学项目的这一奖项支持加州大学圣巴巴拉分校的Peter C.Ford教授继续研究过渡金属络合物所涉及的氮氧化物化学的两个方面。首先，福特教授和他的学生正在研究复杂化合物的合成和光化学性质，其中一部分含有一氧化氮(NO)的前体，当用光激发时，NO可以释放到靶上。复合体的第二部分是一个强吸收天线，它将用于收集光线并将能量转移到NO前体。鉴于NO作为多种生化功能调节因子的重要性，这种NO供体在哺乳动物生物学中具有潜在的应用前景。此外，阐明这类材料的光化学性质的基本原理可以扩展到其他小分子生物调节剂的潜在输送。沿着这些思路，Ford小组发起了一个新的项目，研究纳米材料的制备和基本光物理行为，其中的光吸收天线是直径为2-5 nm的半导体量子点(QD)。量子点具有可调的光学性质，我们现在已经证明了量子点的激发导致了表面上没有前体的反应。正在进行的研究准备了新的材料，并将利用最先进的光物理技术来阐明这些天线将能量传递到反应中心的机制，并探索是否可以利用量子点的非线性光学性质来增强其作为天线的有效性。该项目的另一个技术方面涉及各种氮氧化物在与哺乳动物的氮氧化物生物化学有关的适当配基环境中与铁和铜等金属的反应。正在进行的研究正在使用低温隔离和光谱分析来阐明NOx-金属键合模式和在仔细控制反应物输送和温度变化的情况下的简单反应。对溶液中反应性的相关研究可以表征反应的动力学，如氧原子从配位的NOx物种转移到各种有机分子的反应。例如，人们对亚硝酸盐离子在生理学中的作用越来越感兴趣，目前对该物种的生物无机研究旨在更好地了解所涉及的基本化学过程。在该奖项下进行的研究也作为UCSB本科生和研究生培训的模板，并为博士后学者在创造性奖学金的细微差别方面提供继续教育的模板。与苏必利尔湖州立大学(MI)的Alexei Iretskii教授的持续合作也为Iretskii博士和路易斯安那州立大学本科生提供了研究机会。福特团队的成员与UCBS的其他人员一起积极参与到当地K-12学校的科学推广计划中。离开该群体的本科生进入了研究生和医学院项目，博士和博士后毕业生(包括几个未被充分代表的少数民族)转向独立的工业、政府和教师职位，增强了美国的科学人才库。

This award in the Inorganic, Bioinorganic and Organometallic Chemistry program of the National Science Foundation supports continuing investigations by Prof. Peter C. Ford at the University of California, Santa Barbara into two aspects of nitrogen oxide chemistry involving transition metal complexes. In the first, Prof. Ford and his students are studying the synthesis and photochemical properties of complex compounds for which one part contains a precursor of nitric oxide (NO) that can release this NO to a target upon excitation with light. The second part of the complex is a strongly absorbing antenna, which will serve to gather light and transfer that energy to the NO precursor. Such NO donors have potential applications in mammalian biology given the importance of NO as a regulator of various biochemical functions. Moreover, the fundamental principles in elucidating the photochemical properties of such materials can be extended to the potential delivery of other small molecule bioregulators. Along these lines, the Ford group has initiated a new project investigating the preparation and fundamental photophysical behavior of nanomaterials in which the light absorbing antenna is a semiconductor quantum dot (QD) with diameter of 2-5 nm. Quantum dots have tunable optical properties, and we have now demonstrated that excitation of QDs leads to reactions from NO precursors at the surface. Ongoing studies prepare new materials and will employ state-of-the-art photophysical techniques to elucidate the mechanisms by which these antennas transfer energy to the reactive center and to probe whether the non-linear optical properties of QDs can be exploited to enhance their effectiveness as antennas. The other technical aspect of this project is concerned with the reactions of various nitrogen oxides (NOx) with metals such as iron and copper in appropriate ligand environments relevant to the mammalian biochemistry of the nitrogen oxides. Ongoing studies are using low temperature isolation and spectroscopy to elucidate the NOx--metal bonding modes and simple reactions under carefully controlled delivery of reactants and variation of temperatures. Related studies of the reactivity in solutions allow characterizing the dynamics of reactions such as oxygen atom transfer reactions from coordinated NOx species to various organic molecules. For example, there is increasing interest in the role of nitrite ion in physiology, and the present bioinorganic studies of this species are directed toward providing a better understanding of the fundamental chemical processes that are involved. The research performed under this award also serves as a template for the training of UCSB undergraduate and graduate students and for the further education of postdoctoral scholars in the nuances of creative scholarship. A continuing collaboration with Prof. Alexei Iretskii at Lake Superior State University (MI) also provides research opportunities for Dr. Iretskii and undergraduate LSSU students. Members of the Ford group have participated actively with other UCBS personnel in scientific outreach programs to local K-12 schools. Undergraduates leaving the group have entered graduate and medical school programs and the Ph.D. and postdoctoral graduates (including several underrepresented minorities) have moved on to independent industrial, government and faculty positions, enhancing the US scientific talent pool.