Dr. Ahmadreza Nezamzadeh

Queens University, Canada

Abstract Title: Beyond Wingtips: The Influence of Backbone Alkylation on the Orientation of N-Heterocyclic Carbenes on Gold Nanoparticles

Biography:

My name is Ahmadreza. I received my B.Sc. in Chemistry from Isfahan University of Technology (IUT) in 2013. I remained at IUT to complete my M.Sc. in Organic-Polymer Chemistry. In 2017, I moved to Canada and joined Müller’s lab at the University of Saskatchewan (USASK) to pursue my Ph.D. My research focused on the synthesis of highly strained metallocenophanes bridged by silicon, phosphorus, and boron. These monomers serve as potential precursors for well-defined classes of polymers containing main group and/or transition metal centers. After a 12-year journey in the world of chemistry, I moved to Kingston in February 2023 and joined Crudden’s lab as a Postdoctoral Fellow. My current research focuses on examining the self-assembly of N-heterocyclic carbenes (NHCs) on metal surfaces and developing NHC-supported nanoparticles and nanoclusters.

Research Interest:

Interest in N-heterocyclic carbene (NHC)-based nanomaterials continues to grow, but a thorough understanding of NHC structure-function relationships remains elusive. For instance, previous studies have primarily focused on how tuning NHC wingtips influences the ligand orientation of NHC-decorated nanomaterials.1,2 In this work, we investigate how modifying NHC backbone substituents affects both the ligand orientation and thermal stability of NHC-functionalized gold nanoparticles (AuNPs). Specifically, a series of NHCs were functionalized with alkyl substituents on the backbone. NHC-functionalized AuNPs were then synthesized using either top-down or bottom-up approaches and characterized via UV-Vis spectroscopy, electron microscopy, mass spectrometry, and surface-enhanced Raman spectroscopy (SERS). Experimental SERS data were compared with simulated spectra for vertically and flat-lying NHC ligands. The findings demonstrate that tuning the NHC backbone and wingtips significantly influences ligand orientation on the nanoparticle surface. Moreover, the NHC supported AuNPs exhibited substantial improvements in thermal stability compared to the current state-of-the-art AuNPs. Collectively, these results highlight new synthetic strategies for NHC ligand design to modulate ligand orientation and enhance nanomaterial stability through backbone substituent modifications.