Fluorescent PN-Heterocycles in Supramolecular Chemistry and Recognition

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With the support from 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 will investigate a new class of molecules that contain adjacent phosphorous and nitrogen centers as part of overall structure. These "PN-heterocycles" feature a strong hydrogen bond donor adjacent to a strong acceptor within a compact, fluorescent core. Fundamental supramolecular chemistry is at the heart of this proposal, and our studies will explore and expand the utility of these easily-prepared molecules as fluorescent materials, strong hydrogen bonding motifs for self-assembly and molecular recognition, and supramolecular materials. This project provides interdisciplinary research training to graduate and undergraduate researchers. The broader impacts of this project also include (1) internship opportunities at universities, national labs, and companies, (2) individual development plans, (3) regional/international collaborations; and (4) mentoring opportunities to ensure students receive both a depth of technical training and a breadth of professional training to launch their careers. The PI's commitment to mentoring undergraduate research and to innovation suggests that the research will have broad impact.This fundamental research aims to design and synthesize PN-heterocycles as new fluorophores and as recognition motifs in supramolecular chemistry, organic materials, and molecule/ion recognition. The aims of this project are organized around the following two complementary primary objectives: (1) to perform fundamental studies on these PN-heterocycles in the areas of chiral resolution, organic materials, and new fused-arenes featuring extended conjugation and/or prototropic tautomerism; and (2) to explore the utility of PN-heterocycles in supramolecular chemistry in the areas of hydrogen bond-driven self-assembly, oxoanion recognition, and chiral recognition. The ultimate goal of this research program is to expand the fundamental understanding of these new PN-heterocycles and extend these studies into supramolecular chemistry and molecular recognition. These new heterocycles have the advantage of featuring a very strong hydrogen bonding motif with an inherently fluorescent scaffold, putting both chiral recognition and signal transduction elements directly at the site of recognition and assembly. This research employs a combination of methods, including calorimetric, NMR spectroscopic, 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. The studies provide the researchers with broad experience in organic synthesis, physical organic chemistry, supramolecular chemistry, computational chemistry, X-ray crystallography, and the interplay between electronic structure and molecular architecture.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.