Ligand Dynamics and Chemistry on Locally Curved Metallic Nanoparticle Surfaces

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With the support of the Macromolecular, Supramolecular and Nanochemistry Program in the Division of Chemistry, Dr. Hui Wang of University of South Carolina aims at developing quantitative understanding of the dynamic interactions between molecular ligands and nanoparticle surfaces as well as surface curvature-dependent ligand chemistry and photochemistry. The inorganic cores and the organic ligand shells are two structurally distinct but strongly interplaying components that synergistically determine the collective optical, electronic, and catalytic properties of the nanoparticles. The insights to be gained from this research project will serve as a central knowledge framework that guides the rational optimization of the surface functionalities of colloidal nanoparticles toward targeted applications in catalysis, photocatalysis, photonics, sensing, and biomedicine. This project will create valuable research training opportunities for students at various levels and will be further integrated with outreach activity development. Specifically, Dr. Wang will develop a highly interdisciplinary research and education program on nanoparticle surface chemistry involving broad participation of graduate, undergraduate, and high school students. In addition, Dr. Wang and his students will collaborate with Benedict College, a Historically Black College and University (HBCU) in South Carolina, to develop a long-term partnership on both research and education. Furthermore, the Wang group will work closely with the Electron Microscopy Center at the University of South Carolina on developing educational outreach activities that specifically target the students from local public schools and the participants of the South Carolina State Science Fair.Virtually all chemically synthesized inorganic colloidal nanoparticles, regardless of their dimensions, crystalline structures, and chemical compositions, are coated with a thin layer of organic molecular ligands. This research project involves systematic comparative studies of several deliberately selected nanoparticle-ligand systems to investigate the interfacial dynamics and chemical/photochemical transformations of molecular adsorbates on locally curved metallic nanoparticle surfaces through integrated experimental and computational research efforts. Dr. Wang and his research team will utilize surface-enhanced Raman spectroscopy (SERS) as an ultrasensitive plasmon-enhanced spectroscopic tool to quantitatively correlate the interfacial ligand dynamics with detailed molecular structures under a diverse set of ligand adsorption, desorption, and exchange conditions. SERS will also be used as an in situ spectroscopic tool to fine-revolve detailed structural evolution of the transforming molecular adsorbates on structurally tailored metallic nanoparticle surfaces in real time during chemical and photochemical reactions. The thermodynamic and kinetic results obtained through deliberately designed SERS measurements will be further corroborated by density functional theory calculations to fully unravel how the chemical nature of nanoparticle-adsorbate interactions and the local curvature of nanoparticle surfaces profoundly influence the dynamic interfacial behaviors and the chemical/photochemical reactivities of various types of surface-bound ligand molecules, such as organothiols, isocyanide compounds, terminal alkynes, and diazonium-derived aryl ligands.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.