Fluorescent Azaphosphinines in Supramolecular Chemistry and Recognition

With the support from the Macromolecular, Supramolecular and Nanochemistry Program in the NSF Division of Chemistry, Prof. Michael Haley, Prof. Darren Johnson and their students at the University of Oregon will investigate an underexplored class of molecules that contain adjacent phosphorous and nitrogen centers.

Properly known as azaphosphinines, these “PN-heterocycles” feature a strong hydrogen bond donor adjacent to a strong hydrogen bond acceptor within a compact, fluorescent core. This research will explore and expand the utility of these fluorescent molecules as strong hydrogen bonding motifs for self-assembly and molecular recognition. This project provides interdisciplinary research training to both graduate and undergraduate researchers.

The broader impacts of this project also include: (1) individual development plans, (2) regional, national, and international collaborations, (3) internship opportunities at universities, national labs, and companies, and (4) mentoring opportunities to ensure students receive both a depth of technical training as well as a breadth of professional training to launch their careers. The PIs’ commitment to mentoring, undergraduate research, and innovation ensures the research will have the broadest possible impacts.

This fundamental research aims to design and synthesize azaphosphinines as new fluorophores and as recognition motifs in supramolecular chemistry, organic materials, and molecule/ion recognition. The aims of this project involve study of: (1) quadruple hydrogen-bonded azaphosphinines, (2) azaphosphinine/phenylurea hybrid hosts for oxoanion binding, (3) reduction to PIII azaphosphinines, and (4) azaphosphinines in higher order supramolecular structures.

The goal of our research program is to expand the fundamental understanding of our PN-heterocycles and extend these studies into supramolecular chemistry and molecular recognition. These uncommon heterocycles have the advantage of a very strong hydrogen bonding motif within 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 NMR spectroscopic and UV-Vis 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.

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.