NSF Award
2420332
The NSF Center for Aqueous Supramolecular Chemistry (CASC) is supported by the Centers for Chemical Innovation (CCI) Program of the Division of Chemistry. The ability of custom-designed molecules to 1) selectively recognize and bind to negatively charged molecules (anions), 2) transport these anions across membranes and/or 3) enable chemical transformations to new products is an all-but-unmet challenge. This Center will overcome these challenges by synthesizing novel molecules that target two anions of particular importance to society: bicarbonate and perfluorooctanoic acid (PFOA). Carbon dioxide from greenhouse gas emissions resides predominantly in surface ocean waters as bicarbonate. PFOA is well recognized for its persistence and toxic effects in groundwater. The selective capture, transport and transformation of these two anions will foster numerous technological payoffs. Activities within this Center include the training of students in the commercialization of technology and the creation of custom Individual Development Plans for all incoming scholars. CASC will establish a summer undergraduate program that trains students to continue projects at their home institution, and for informal science communication will engage the public in hands-on activities at museums and science centers.<br/><br/>CASC will enable the supramolecular control, transport and transformation of oxy and fluorinated anions, a widely recognized and longstanding challenge. The two targeted anions, bicarbonate and PFOA, represent two extremes in terms of size, shape, and solvation, features that will aid in the establishment of fundamental supramolecular principles applicable to a broad chemical landscape. Supramolecular recognition of anions will be manifested via the incorporation of fluxional receptors whose primary recognition motifs are unique ionic, hydrogen, or halogen bonds that are exquisitely sensitive to the local electronic and electrostatic environment. CASC will demonstrate this by adjusting these forces within supramolecular host guest complexes; both the affinity and selectivity of the host guest complexes can be manipulated to enable the design of a new class of switchable receptors. By exploiting electronic and electrostatic forces between a host and its guest, on-demand allosteric control over both the binding and release processes will be established for the transport of ions across lipid bilayer or polymeric membranes. Switchable supramolecular receptors will be utilized as directing agents to improve the reactivity of catalysts and foster transformation. Bicarbonate receptors will be conjugated to reduction catalysts that include iron and iridium complexes, and PFOA receptors will be grafted onto alumina or conjugated with photobases such as malachite green carbinol molecules. The ability to control both affinity and selectivity will propel anion supramolecular chemistry into novel domains that extend beyond recognition and sensing. A newfound capability to simultaneously transport and transform anions in water will impact environmental chemistry, chemical biology, and catalysis.<br/><br/>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.
