MOLECULAR ENCAPSULATION AND ELECTRON TRANSFER

美国国家科学基金会化学部的有机和大分子化学项目支持迈阿密大学的Angel E. Kaifer教授，他将研究分子结构和电子转移反应之间的关系和相互作用。这一建议旨在阐明与电子转移（ET）反应有关的基本问题，以及在超分子系统中，寄主如何影响ET速率。为了更好地理解发生在非共价包封氧化还原中心内的电子转移反应，这是先前工作的主要持续努力。通过使用氧化还原活性客体和合适的宿主，所得到的包合物是氧化还原中心部分或完全被宿主腔包裹的结构。它可以看作是类似于生物主-客大分子系统。这些实验将试图了解包封分子反应性的定量和定性变化，如重组能率和相关热力学参数。具体目标是i)通过非共价结合相互作用研究二茂铁及其衍生物在各种葫芦[n]脲（CBn）和空腔和宿主中的作用，ii)研究完全封装的铁中心和电极表面之间的介导电子转移，iii)继续研究CBn宿主在一系列包合物中的结合特性。iv)开展利用氮氧化物自旋标签探测分子胶囊内部空间的新研究，以更好地了解控制自组装的复杂因素。由于CBn宿主在结合亲和力和选择性上超过了环糊精（一类类似的环状低聚糖），因此这些研究将为更好地理解一类有价值的分子的超分子组装和分子识别提供有意义的信息。葫芦素是一种高效的分子识别宿主分子，可以作为超分子催化剂、药物传递载体、信息存储设备或其他材料科学应用中发挥作用。Kaifer教授将继续积极地让女性和少数族裔从高中到博士后都参与到他的研究项目中。除了正在进行的优秀研究外，Kaifer教授还强调学生的培养超越了传统化学学科的界限。所有小组成员都需要发展合成专业知识，必须进行自己的电化学和光谱实验，以表征电子转移反应，主客体结合相互作用，自组装和/或聚集过程，他们的目标化合物可能参与。π吗?S集团一直为弱势群体的研究人员的发展和培训提供友好和培育的氛围。这个应用程序的几个研究部分是专门为本科生设计的，因为他们的研究工作经常受到时间表限制，而不影响研究生和博士后助理。就少数民族培训的可衡量成果而言，Kaifer教授承诺，本项目的研究参与者将包括：(a)每年一名少数民族/女本科生，(b)每年一名少数民族/女高中生，(b)在资助周期内至少有一名少数民族/女博士后或研究生。

The Organic and Macromolecular Chemistry Program in the Chemistry Division at the National Science Foundation supports Professor Angel E. Kaifer at the University of Miami, who will study the relationship and interplay between molecular structures and electron transfer reactions. This proposal is aimed at elucidating fundamental questions related to electron transfer (ET) reactions and how the ET rates are affected by a host in supramolecular systems. This is a major continuing effort of previous work to better understand electron transfer reactions that occur within noncovalent encapsulated redox centers. By using a redox active guest and a suitable host, the resulting inclusion complex is a structure in which the redox center is partially or completely encapsulated by the host cavity. It may be viewed as analogous to biological host-guest macromolecular systems. These experiments will seek to understand quantitative and qualitative changes in reactivity of encapsulated molecules, such as reorganization energy rates and related thermodynamic parameters. Specific objectives are to i) investigate ferrocene and its derivatives in various cucurbit[n]uril (CBn) and cavitand hosts via noncovalent binding interactions, ii) investigate mediated electron transfer between fully encapsulated ferrocence centers and electrode surfaces, iii) continue binding property studies of CBn hosts within a range of inclusion complexes, and iv) begin new research on the use of nitroxide spin labels to probe the interior space of molecular capsules to better understand the complex factors controlling self-assembly. Since CBn hosts surpass cyclodextrins, a similar class of cyclical-shaped oligosaccharides, in binding affinity and selectivity, these studies will generate meaningful information to better understand supramolecular assembly and molecular recognition of a valuable class of molecules. Cucurbiturils are efficient host molecules in molecular recognition and may find applications as supramolecular catalysts, drug delivery vehicles, play a role in information storage devices, or other materials science applications. Professor Kaifer will continue to actively engage women and underrepresented minorities from high school to post-doctoral levels in his research program. In addition to the excellent research being carried out, Professor Kaifer emphasizes student training beyond the boundaries of the traditional disciplines of chemistry. All group members are required to develop synthetic expertise and must perform their own electrochemical and spectroscopic experiments to characterize the electron transfer reactions, host-guest binding interactions, self-assembly and/or aggregation processes in which their target compounds may engage. The PI?s group has always bestowed a friendly and nurturing atmosphere for the development and training of underrepresented minorities as researchers. Several research components of this application are specifically designed for undergraduate students, since their research work often suffers from schedule limitations that do not affect graduate students and postdoctoral associates. In terms of measurable outcomes in minority training, Professor Kaifer makes the commitment that the research participants in this project will include: (a) a minority/female undergraduate every year, (b) a minority/female high school student every year, and (b) at least a minority/female postdoctoral associate or graduate student during the grant cycle.