Small molecule activation and sensing

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The proposed research program is focused on the activation and detection of small molecules. The first objective is to develop fundamentally new and green ways to capture carbon dioxide, which is a potent greenhouse gas and carbon waste from the combustion of all fossil fuels, and to utilize it as sustainable one-carbon feedstock to prepare value-added organic products. In 2013, our group developed a series of compounds (including a metal-free one), which can selectively break one of their own carbon-hydrogen bonds and store one molecule of carbon dioxide in between. We will apply the knowledge gained from this recent breakthrough to design new systems that can selectively break other types of bonds and store carbon dioxide in between. Moreover, we will develop catalytic processes to convert the stored carbon dioxide into organic compounds (such as formate) which have important industrial applications. The second objective is to solve the mystery of how nature converts atmospheric dinitrogen into ammonia and to learn how to make other nitrogen compounds directly from dinitrogen. We will prepare novel iron compounds that structurally resemble the active site of nitrogenase (nature’s enzyme that converts dinitrogen into ammonia) and investigate the reactivity of these compounds toward dinitrogen to deduce the nitrogenase behaviours. One puzzling feature of the nitrogenase activity is the loss of dihydrogen upon dinitrogen binding on an iron centre at the active site. In 2010, our group observed an analogous reactivity when heating a ruthenium (the element right below iron in the periodic table) compound under dinitrogen, i.e., dinitrogen binds with the ruthenium centre with concomitant loss of dihydrogen. Prompted by this analogy, we will further explore the reactivity of the ruthenium-bound dinitrogen, which may provide insight into the reactivity patterns of metal-bound dinitrogen. Information gained from this research will shed light on how nature converts dinitrogen into ammonia and help us harness dinitrogen reactivity to make nitrogen-containing organic compounds directly from the abundant dinitrogen gas from air. The third objective is to design luminescent sensors for detecting ecotoxins. In 2013, our group developed a selective sensor for DMF vapor, which is responsible for several occupational health problems at leather and synthetic fibre factories, and studied the underlying mechanism. We will apply this knowledge to the design of sensors for detecting nitrate and formaldehyde; the former is a prevalent harmful chemical found worldwide in urban homes and furniture, while the latter is a pollutant in drinking water caused by the overuse of fertilizers. Efforts will also be made to generalize the principle of our sensor design toward the sensing of other environmentally concerned chemicals. The successful outcome will result in portable sensors for the facile detection of pollutants in air and water. All these projects have positive environmental impacts, and contribute to the advancement of knowledge at both fundamental and practical levels.