This talk will describe microdroplet chemistry where chemical reactions are carried out in micro-sized liquid droplets (microdroplets) and its application to Catalysis, Material Synthesis, and Biology. I have found unique and interesting properties of molecular behaviors and chemical reactions occurring in microdroplets. We have found a markedly high acceleration of reaction rates in microdroplets compared to bulk solutions by factors of 10<sup>3</sup> to 10<sup>6</sup> for the reactions including protein unfolding, protein-ligand interaction, redox reaction, and chlorophyll demetallation. This enhanced reaction rates in microdroplets allow an efficient and environmentally benign synthesis of difficult reaction products without using any catalyst. Thermodynamically unfavorable reactions in bulk solution, such as phosphorylation of various sugars and ribonucleosides, can proceed in microdroplets at room temperature without any added chemical, catalyst, or energy source due to the lowered entropic barrier at the water surface. The rapid fusion of microdroplets also enables kinetically controlled crystallization of gold nanoparticles. Interestingly, we have found that microdroplet surface allowed reducing agent-free and template-free crystallization of gold ions and the formation of metal nanostructures including nanoparticles, nanowires, and nanosheets. The application of these nanostructures for oxygen reduction reaction (ORR), oxygen evolution reaction (OER), and the hydrogen evolution reaction (HER) will be discussed. I will also discuss about how new findings from the microdroplet chemistry can impact the biological science or engineering through the studies of mesoscale chemistry, chemistry occurring in the range from the size of assembled molecules (~100 nm) to eukaryotic cells (~10 µm) where different molecular behaviors arise, which cannot be well described by the laws on the atomic or bulk scale.

Microdroplet chemistry for catalysis, material synthesis, and biology

2019 Fall National Meeting

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