Anion Binding in Chiral Cyclotribenzoin Esters

In this NSF-funded project, Prof. Miljanic and his research group at the University of Houston will study the binding of anions—negatively charged ions with important roles in the environment (nitrate and phosphate anions), energy (nitrate, pertechnetate, perchlorate), and biology (chloride, sulfate, organic phosphates, carboxylates). Anion binding is important for diagnostics, environmental remediation, and in nuclear, space, and explosives industries. Miljanic and his team will use a family of small organic molecules known as cyclotribenzoin esters, which they pioneered. The project aims to study the impact of molecular structure on binding strength and to develop binders that can distinguish between biologically relevant anions. Results from this project will impact efforts in advanced manufacturing by offering blueprints for the development of environmentally responsive next-generation materials. Apart from its scientific impact, this project will benefit society at large by workforce training at the interface of organic and supramolecular chemistry, involvement of high school students in original scientific research, curriculum advances at the University of Houston, and technology transfer. Cyclobenzoin esters are readily prepared organic macrocycles whose cone-shaped structures project multiple carbon–hydrogen convergently toward a single point, where anion binding occurs. Using the tools of synthetic and physical organic chemistry, this project will examine the impact of structural modifications—such as expansion of the aromatic skeleton, bromination, deuteration, or side-group modification—on the strength of anion binding. As cyclobenzoin esters are also inherently chiral, they will be exploited to create anion receptors capable of discriminating between enantiomeric anions of biological relevance. Anion binding will be analyzed using nuclear magnetic resonance spectroscopy and X-ray crystallography. 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.