RUI: Exploring Halogen Bonding as a Fundamental Interaction Toward the Development of Nanoparticle-Based Screening Methods for Explosive Molecule Detection

在化学系大分子、超分子和纳米化学(MSN)计划的支持下，里士满大学的Michael C.Leopold教授和他的本科生将探索卤素键的化学，努力利用其独特的有吸引力的相互作用来开发爆炸物和结构相关化合物的纳米颗粒传感平台。长期的实际目标是开发快速、非专家可操作、现场可携带、执法和军方可部署的基于卤素结合纳米颗粒的爆炸物传感工具。在根本方面，该项目促进了对依赖于结构的卤键相互作用的知识和基础理解，并将这种知识应用于在传感方案中发挥功能作用的纳米材料的设计。该项目让本科生从事根本性的、多学科的、实用的以结果为导向的研究。除了身临其境的实验室体验外，本科生还将帮助开发基于课程的本科生研究材料，并将积极参与社区教育和外联计划，旨在激发和保持当地资源不足的K-12学校对STEM领域的兴趣。本项目的重点是结构优化的卤素键(XB)，作为战略设计的XB选择器分子与金纳米颗粒(NPs)偶联的XB分子与目标爆炸分子之间的基本分子间相互作用。促进这些功能化的NPs和非芳香族炸药之间强烈的XB相互作用应该会导致分析信号，光谱或电化学，表明目标分子的存在。为了实现这一总体目标，有一些具体的目标，包括：(1)使用19F和1H核磁共振(核磁共振)滴定测量来确定特定的卤化化学结构和实验条件，以使X-B与炸药和/或与爆炸相关的分子发生最强的相互作用；(2)合成具有优化的X-B促进化学结构的硫醇端基配体；(3)探索单层保护的纳米团簇(MPC)的表面结构/化学，以通过核磁共振测量监测的位置交换反应，有效地使其外围层与X-B选择配体官能化；(4)使用精密的二维核磁共振、核增强谱(NOESY)和异核增强谱(HOESY)方法表征官能化MPC与炸药/炸药相关靶分子之间的X-B相互作用：(5)探索在炸药分子存在下X-B诱导选择剂修饰的MPC的溶液聚集；(6)展示了X-B选择器在组装薄膜中的功能化MPC，作为通过电化学测量检测化学蒸气中的爆炸物和/或与爆炸物相关的分子的接口。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势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 (MSN) Program in the Division of Chemistry, Professor Michael C. Leopold of the University of Richmond and his undergraduate students will explore the chemistry of the halogen bond in an effort to exploit its unique attractive interactions to develop nanoparticle sensing platforms for explosives and structurally-related compounds. The long-term practical objective is to develop halogen bonding nanoparticle-based explosive sensing tools that are fast, operable by non-experts, field portable and deployable by law enforcement and the military. On the fundamental side, the project advances knowledge and fundamental understanding of structure-dependent halogen bond interactions and adapts this knowledge to the design of nanomaterials that serve a functional role within sensing schemes. The project engages undergraduate students in fundamentally-sound, multidisciplinary, practical outcome-oriented research. In addition to an immersive laboratory experience, undergraduate students will assist in the development of curriculum-based undergraduate research material and will actively participate in community educational and outreach programs aimed at inspiring and retaining interest in STEM fields at local under-resourced K-12 schools. This project focuses on structure-optimized halogen bonding (XB) as a fundamental intermolecular interaction between strategically-designed XB selector molecules coupled to gold nanoparticles (NPs) and the targeted explosive molecules. Promotion of strong XB interactions between these functionalized NPs and non-aromatic explosives should lead to analytical signaling, spectroscopic or electrochemical, that indicates the presence of targeted molecules. To accomplish this overarching goal, there are a number of specific objectives including: (1) the use of 19F and 1H NMR (nuclear magnetic resonance) titration measurements to identify specific halogenated chemical structure and experimental conditions for the strongest X-B interactions with explosives and/or explosive-related molecules; (2) synthesis of thiol-terminated ligands with optimized X-B promoting chemical structure; (3) exploration of the surface structure/chemistry of monolayer protected nanoclusters (MPCs) to effectively functionalize their peripheral layer with X-B selector ligands via place-exchange reactions monitored with NMR measurements; (4) the use of sophisticated 2-D NMR, NOESY (Nuclear Overhauser Enhancement Spectroscopy) and HOESY (Heteronuclear Overhauser Enhancement Spectroscopy) methods, to characterize X-B interactions between functionalized MPCs and explosive/explosive-related target molecules; (5) exploration of X-B induced solution aggregation of selector-modified MPCs in the presence of explosive molecules; (6) demonstration of X-B selector functionalized MPCs within assembled films as an interface for detecting explosives and/or explosive-related molecules in chemical vapor via electrochemical measurements.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.