Redox-Responsive H-Bonding Systems for Supramolecular Applications

在化学系大分子，超分子和纳米化学项目的支持下，圣地亚哥州立大学的Diane Smith教授将探索新的方法来选择性地控制分子之间的相互作用强度，使用电子转移结合质子转移。 所涉及的分子可以被认为是天然碱基对的合成亲属，天然碱基对将DNA双螺旋的两条链连接在一起。 这些天然碱基对以高度特异性的方式连接在一起，这是可靠传递遗传信息所必需的特征。 在研究中的合成版本中，连接也是高度特异性的，但是，与它们的天然表亲不同，连接的强度应该是可切换的，通过使用电子转移诱导碱基对之间的质子转移，可逆地从弱到强。 由此产生的高度选择性的ON/OFF结合可以在各种智能材料和传感系统以及分子器件和机器中找到应用。 此外，研究本身涉及各种技能，将为所涉及的不同学生群体提供优秀，全面的教育，包括研究生，本科生和高中生，其中许多人来自科学代表性不足的群体。本计画的主要目标是探讨利用电子转移来大幅改变氢键结合强度的一般性，并测试其局限性（H-键）异二聚体（碱基对）通过诱导质子转移穿过H-键。这改变了二级氢键的性质，众所周知二级氢键会强烈影响整体结合强度。在该项目的目标1中，Smith教授和她的学生的目标是显着扩展先前的结果，其中通过使用相同的基于还原的氧化还原对来创建4和6个H-键异二聚体，并通过探索使用2种不同的基于氧化的对来创建新的高度氧化还原响应的3 H-键二聚体，观察到3 H-键二聚体的结合强度增加了10^5倍。此外，在专门为本科生设计的子项目中，将使用简单的2 H键系统探索控制效应强度的基本问题，并且在目标2中，在高中实习生的帮助下，该团队将确定溶液化学的难易程度可以通过将电活性成分附着到电极表面来将其转化到表面。目标3将研究氢键二聚体与氧化态之间的结合强度有很大的变化，是否可以用于构建高度氧化还原响应的超分子聚合物。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

With the support of the Macromolecular, Supramolecular and Nanochemistry Program in the Division of Chemistry, Professor Diane Smith of San Diego State University will be exploring new methods to selectively control the strength of interactions between molecules using electron transfer combined with proton transfer. The molecules involved can be thought of as synthetic relatives of the natural base pairs that link together the two strands of the DNA double helix. These natural base pairs link together in a highly specific fashion, a feature necessary for the reliable transfer of genetic information. In the synthetic versions under investigation, the linkages also are highly specific, but, unlike their natural cousins, the strength of the linkage should be switchable, reversibly going from weak to strong by using electron transfer to induce proton transfer between base pairs. The resulting highly selective ON/OFF binding may find application in a variety of smart materials and sensing systems, as well as molecular devices and machines. In addition, the research itself, which involves a variety of skill sets, will provide an excellent, well-rounded education to the diverse group of students involved, including graduate, undergraduate and high school students, many of whom are from groups underrepresented in science.More specifically, the primary goal of this project is to explore the generality and test the limits of using electron transfer to greatly alter binding strength in hydrogen bond (H-bond) heterodimers (base pairs) by inducing proton transfer across a H-bond. This changes the nature of the secondary H-bonds, which are well-known to strongly affect overall binding strength. In Aim 1 of this project, Professor Smith and her students aim to significantly expand upon a previous result in which a 10^5-fold increase in binding strength in a 3 H-bond dimer is observed by using the same reduction-based redox couple to create 4 and 6 H-bond heterodimers and by exploring the use of 2 different oxidation-based couples to create new highly redox-responsive 3 H-bond dimers. Furthermore, fundamental issues governing the strength of the effect will be explored with simple 2 H-bond systems in a sub-project specifically designed for undergraduates, and, in Aim 2, aided by high school interns, the team will determine the ease with which the solution chemistry can be translated to surfaces by attaching the electro-active component to electrode surfaces. Aim 3 will investigate whether H-bond dimers with very large changes in binding strength between oxidation states can be used to advantage for the construction of highly redox-responsive supramolecular polymers.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.