Medium Matters: Merging Photochemistry with Supramolecular-, Nano-, and Green Chemistries

生物系统中化学过程的效率和选择性通常源于反应物在高度受限和有组织的环境中的定位。 这些过程中的一些（例如，光合作用）利用光作为驱动反应的能量来源。 迈阿密大学的Vaidhyanathan Ramamurthy教授的研究项目侧重于对受限空间中分子性质的基本理解，并探索利用光在水中引发反应。 长期目标是解决国家在可持续性方面的需求，方法是开发有效的方法，通过水的转化（避免与使用有机溶剂有关的环境问题），捕获阳光（一种可持续的能源）并将其转化为化学能。 这个涉及国内和国际合作的跨学科项目为研究生和博士后研究人员提供研究培训。此外，Ramamurthy教授还接触了美国国内外大学的本科生和研究生，并通过他的一般讲座激励年轻研究人员成为成功的科学家，这些讲座强调了基础科学在日常应用中的重要性。为了了解分子在受限环境中的行为并提高水中反应的选择性和有效性，Ramamurthy教授的团队合成了水溶性空腔，这些空腔封装了有机分子，并作为具有几埃尺寸的反应容器。 该研究小组研究了通过光诱导电子从封装的供体穿过囊壁转移到受体（例如，水溶性敏化剂或TiO 2），利用太阳能在水中进行化学转化。 正在研究的光化学反应包括烯烃和环丙烷的几何异构化、产生高能环丁烷的环加成反应、产生高应变分子的价异构化和环反转反应。 光谱研究，包括超快（ns-fs）实验，用于测量电子转移速率，识别自由基离子中间体，确定中间体的反应性，并阐明产品结构。该奖项反映了NSF的法定使命，并被认为是值得通过使用基金会的智力价值和更广泛的影响审查标准进行评估的支持。

The efficiency and selectivity of chemical processes in biological systems often stem from the localization of reactants in highly restricted and organized environments. Some of these processes (e.g., photosynthesis) harness light as the source of energy for driving the reactions. The research program of Prof. Vaidhyanathan Ramamurthy at University of Miami focuses on fundamental understanding of the properties of molecules in confined space and exploring the use of light to initiate reactions in water. The long-term goal is to address the national needs in sustainability by developing efficient methods for capturing and converting sunlight (a sustainable source of energy) into chemical energy through transformations in water (that avoids environmental issues associated with the use of organic solvents). This interdisciplinary project involving domestic and international collaborations provides research training to graduate students and postdoctoral researchers. Additionally, Prof. Ramamurthy reaches out to undergraduate and graduate students at universities within and outside USA and motivates young researchers toward becoming successful scientists through his general lectures that highlight the importance of basic science in the context of everyday applications. With the goal of understanding the behavior of molecules in confined environments and enhancing the selectivity and efficacy of reactions in water, Prof. Ramamurthy's group synthesizes water-soluble cavitands that encapsulate organic molecules and serve as reaction vessels with dimensions of a few angstroms. The research team investigates the generation of reactive organic radical ions in the capsule by photoinduced electron transfer from encapsulated donors across the capsular wall to acceptors (e.g., a water-soluble sensitizer or TiO2) present outside, harnessing solar energy for chemical transformations in water. The photochemical reactions being studied include the geometric isomerization of olefins and cyclopropanes, cycloaddition reactions to produce energy rich cyclobutanes, valence isomerization to generate highly strained molecules and cycloreversion reactions. Spectroscopic studies, including ultrafast (ns-fs) experiments, are performed to measure the rates of electron transfer, identify the radical ion intermediates, determine the reactivity of the intermediates, and elucidate the product structures.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.