Heterogeneous phase catalysis plays a fundamental role in terrestrial industrial chemistry, and its importance in the synthesis of Complex Organic Matter (COM) in cosmic environments is steadily increasing. Our group has focused on a reliable theoretical model cluster, the Polyhedral Oligomeric Silsesquioxanes, or POSSs. The POSS models are based on the known prevalence of silicon/oxygen-containing solid matter found on comets and rocky body surfaces like asteroids, planetoids, and moons with the terrestrially well-recognized catalytic activity of siloxyl radicals (SiO●) exposed on a silica surface. The SiO● radicals catalyze several important organic chemical reactions at relatively low temperature (much less than 200 K). The POSS-SiO● system works as a “defective” silica surface, where further chemical defects such as natural dopants like catalytic transition metals, have enormous potential to contribute to astrochemistry and prebiotic/Origin of Life chemistry. Recently, we proposed a mechanism for polymerization of various astrochemically relevant species (CO, HCN, N<sub>2</sub>, NH<sub>3</sub>, etc.) on a SiO● radical (T=200 K) on the POSS surface. Such temperatures can be experienced, for example, by comets where temperature rises periodically by surface heating to release CO and H molecules or by dust particles or greater bodies in the turbulent phase of a proto-planetary disk. Overall, polymerization gives rise to the formation of prebiotic molecules such as polyols, carbohydrates, ketones, aldehydes, keto-nitriles, and more.  Most recently, we have shown the POSS cluster model can catalyze an effectively barrierless and regioselective hydrocyanation reaction of propene when one silicon is replaced with a Ni(I) center. Finally, proposed heterogenous mechanisms computed with Density Functional Theory have been calibrated with domain-based local pair natural orbital coupled-cluster theory [DLPNO-CCSD(T)] and both levels of theory show satisfactory agreement.

Catalytic “chemical defects” contributing to origin of life chemistry

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