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

点击翻译按钮获取中文摘要

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.