NSF Award
2404020
With the support of the Macromolecular, Supramolecular and Nanochemistry Program in the Division of Chemistry, Professor Jon Camden of the University of Notre Dame and Professor David Jenkins of the University of Tennessee will investigate the properties and application of N-heterocyclic carbenes (NHCs) as capping ligands on gold and silver nanoparticles. These noble metal nanoparticles and their assemblies are central components in wide-ranging chemical, biological, and environmental technologies. Critically, these nanoparticles do not work alone and in almost all cases, their function arises from the molecules adsorbed to the noble-metal surface. In the last decade, N-heterocyclic carbenes have emerged as an exciting alternative functionalization platform to sulfur ligands for noble metal nanoparticles. NHC-functionalized nanoparticles are now being studied for many applications including electrocatalytic reduction of carbon dioxide Despite this substantial success, current NHC ligands for nanoparticle applications are all structurally similar. For this proposal, the Camden and Jenkins research teams will rationally design new NHC ligands for nanoparticles to improve their robustness and expand their applicability. Finally, Professors Camden and Jenkins will support two positions in a STEM (science, technology, engineering and mathematics) Teaching Fellows Residency program that will take place during the summer.<br/><br/>This collaborative project between the Camden research team at the University of Notre Dame and the Jenkins research team of the University of Tennessee will address three outstanding fundamental scientific questions and challenges for use of N-heterocyclic (NHC) ligands in nanoparticle research. First, the collaborative team will perform a series of isotope labeling experiments to study the NHC transfer process and exchange dynamics on nanoparticle (NP) surfaces. Second, the researchers will synthesize new macrocyclic and hemispherical bidentate NHC ligands for gold nanoparticles to increase electrochemical and chemical resistance. Third, the team will design NHC ligands with chemically addressable functional groups that are capable of stabilizing gold nanoparticles (AuNPs) in aqueous or organic environments, respectively, to establish their potential for post-synthetic modifications with model analytes. These studies will focus on a top-down approach wherein the AuNPs are prepared and then functionalized NHCs transferred from isolated coinage metal NHC complexes. A top-down approach is beneficial because multiple sizes and shapes of AuNPs can be prepared and the NHC transfer reactions are more universal compared to a bottom-up approach where each individual reaction must be optimized to form AuNPs.<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.
