INFEWS N/P/H2O: SusChEM: New Molecular Receptors to Complete the Loop on Nitrogen/Phosphorus Fertilizer Use and Detection

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Nitrogen and phosphorus compounds are the main ingredients of fertilizers used to increase crop yields on farms. While nitrogen and phosphorus are helpful plant nutrients in low dosage, excess fertilizer can cause environmental problems when the same compounds are washed by rainwater from the soil into streams and rivers. There is a pressing need to develop sensors able to measure, in real-time, accurate concentrations of nitrogen and phosphorus concentrations. These measurement inform decisions on fertilizer management in agriculture and wastewater treatment. Such measurements can be used to maximize fertilizer benefits while minimizing environmental impacts. With the support of the Macromolecular, Supramolecular and Nanochemistry Program of the NSF Chemistry Division, Professors Michael Haley and Darren Johnson, and their students at the University of Oregon are designing improved sensors for fertilizer management and environmental protection. This project provides interdisciplinary training to graduate and undergraduate researchers. The broader impacts of this project also include industrial internships of graduate students at local and regional companies and continued involvement of undergraduates in chemical research via programs that promote participation of underrepresented groups. This fundamental research aims to design and synthesize molecular probes that are selective for environmentally relevant components of fertilizers. The long-term goal is to produce molecular receptors with improved precision and accuracy for the agriculture industry. The researchers design and synthesize two new families of molecular receptors for binding and sensing important anions such as nitrite and dihydrogen phosphate. The first family is based on aryl-acetylene scaffolding and the second is based on the facile synthesis of highly fluorescent phosphaquinolin-2-ones. This research employs a combination of methods (including calorimetric, NMR, and spectrophotometric titrations) to determine the binding properties of the supramolecular receptors and to gain a better understanding of how structural changes influence their binding affinity, selectivity, and optoelectronic properties. In addition, the team develops high throughput assays to efficiently identify receptors for nutrient sensing. The studies provide the researchers with broad experience in organic synthesis, physical organic chemistry, computational chemistry, x-ray crystallography, and the interplay between electronic structure and molecular architecture. Industrial internships at local and regional companies are available for graduate students. Undergraduate chemical research opportunities promote participation of underrepresented groups.