Electrostatic Regulation of Cavity-Mediated Catalysis

University Of South Dakota Main Campus, Vermillion SD

Investigators

Abstract

Catalysis is a process in which a small amount of a substance (a catalyst) accelerates the rate of desirable chemical reactions. Catalysis plays a vital role in many industrial applications. Manufacturing valuable products such as pharmaceuticals, plastics, agrochemicals, and clean fuels often requires properly designed catalysts. Traditional catalysts are highly effective in promoting a wide range of chemical reactions. However, it remains a daunting task to make catalysts that emulate the remarkable performance of enzymes, which are Nature's catalysts. The challenge arises largely from the difficulty of constructing molecules that resemble the complexity of enzymes. In this project, Dr. Zhenqiang Wang of the University of South Dakota is applying several biology-inspired principles to synthesize new classes of molecules that mimic enzymes. This research is integrated with educational outreach programs targeting Native American students to promote STEM (science, technology, engineering, and mathematics) education. These programs are engaging local tribal college students through tribal student-faculty research teams hosted in Dr. Wang's laboratory and through chemistry workshops at regional tribal colleges. The outreach also includes onsite hosting of students from local primarily undergraduate institutions (PUIs) and "at-home" support for student-faculty research teams at their home institutions. In this project funded by the Chemical Catalysis program of the Chemistry Division, the team led by Dr. Wang at the University of South Dakota is utilizing a unique class of synthetic receptors, known as metal-organic supercontainers (MOSCs), to investigate new concepts of catalysis. The MOSC-based supramolecular catalysts are structurally unique in that they are constructed from container-molecule precursors (i.e., sulfonylcalixarenes) and feature multiple nano-cavities that serve as substrate binding sites. The MOSC catalysts also feature functionally versatile metal-bound H2O species, which may promote hydrogen-bond, Bronsted-acid, Bronsted-base, and cascade catalysis. Two key strategies, namely, multifunctional nano-cavities and electrostatic regulation, are used to promote the catalytic efficacy, enhance reaction selectivity, and regulate supramolecular reactivity. The unique structural characteristics of the MOSCs, including their compositional versatility, structural modularity, and multi-pore architecture, distinguish them from other synthetic receptor molecules and provide unprecedented opportunities for functionalizing catalytic active sites and engineering supramolecular reactivity. The strategy to modulate supramolecular catalysis using ionic species as electrostatic regulators, which are catalytically inert on their own, is conceptually distinct from conventional methods that rely on encapsulating catalytically active species. The concept of electrostatic regulation is not yet fully recognized by chemists, but has the potential to not only significantly expand the scope of accessible reactions, but fundamentally transform how supramolecular catalysis can be designed. 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.