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黛安·史密斯教授将探索利用电子转移和质子转移相结合来选择性控制分子间相互作用强度的新方法。所涉及的分子可以被认为是连接DNA双螺旋两条链的天然碱基对的合成亲戚。这些天然碱基对以一种高度特定的方式连接在一起，这是遗传信息可靠传递所必需的特征。在研究中的合成版本中，这些键也是高度特异性的，但是，与它们的天然表亲不同的是，这些键的强度应该是可切换的，通过利用电子转移来诱导碱基对之间的质子转移，可以从弱到强可逆地转换。由此产生的高选择性ON/OFF结合可以应用于各种智能材料和传感系统，以及分子设备和机器。此外，这项涉及多种技能的研究本身，将为包括研究生、本科生和高中生在内的不同学生群体提供优质、全面的教育，其中许多人来自科学领域代表性不足的群体。更具体地说，本项目的主要目标是通过诱导氢键上的质子转移，探索利用电子转移来极大地改变氢键（h键）异源二聚体（碱基对）结合强度的普遍性和测试局限性。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。在这个项目的目标1中，Smith教授和她的学生们的目标是显著扩展先前的结果，即通过使用相同的还原基氧化还原对来创建4和6氢键异二聚体，并通过探索使用两种不同的氧化基对来创建新的高度氧化还原反应的3氢键二聚体，观察到3氢键二聚体的结合强度增加了10^5倍。此外，控制效应强度的基本问题将在专门为本科生设计的子项目中通过简单的2氢键系统进行探索，并且，在目标2中，在高中实习生的帮助下，团队将确定通过将电活性成分附着在电极表面来将溶液化学转化为表面的难易程度。目的3将研究在氧化态之间结合强度变化非常大的氢键二聚体是否可以用于构建高度氧化还原反应的超分子聚合物。该奖项反映了美国国家科学基金会的法定使命，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.