Size controlled, structural characterization and applications of glucopyranoside-based N-heterocyclic carbenes stabilized gold nanoparticles.

• Extra-small and ultra-stable sugar-substituted NHC stabilized AuNPs were synthesized by one-pot method. • Chiral AuNPs were characterized by UV–Vis, NMR, HR-TEM, TGA, CD, FT-IR, and XPS spectroscopy. • Chiral AuNPs with core diameters ranging from 2.3 to 3.8 nm remained ultra-stable against glutathione. • Chiral AuNPs exhibited excellent antibacterial activity against bacterium Xanthomonas citri susp. citri. • Chiral AuNPs exhibited excellent catalytic activity towards the reduction of nitroarenes. N -heterocyclic carbenes (NHCs) have evidenced wonderful alternatives as surface ligands, while synthetic challenges have limited their application in chiral gold nanoparticles (AuNPs). To avoid using difficult-to-synthesize and light-sensitive NHC-Au(I) complex, we synthesized four glucopyranoside-based benzimidazolium bromide salts (1a – 1d-Br) and their corresponding haloaurate(III) salts (2a – 2d-AuCl 4). Then, the first-generation sugar-substituted NHCs stabilized extra-small and ultra-stable chiral AuNPs (Au@NHCs-sugar NPs, 3a – 3d-AuNPs) was synthesized though two mild, efficient, and operation-friendly one-pot chemical reduction methods. The obtained 3a – 3d-AuNPs were characterized by UV–Vis, NMR, HR-TEM, TGA, CD, FT-IR, and XPS spectroscopy. The designed 3a – 3d-AuNPs with core diameters ranging from 2.3 to 3.8 nm remained stable against glutathione for up to 24 h over a wide temperature range of 95 to −78 °C, and over 4 years in air. The absence of NC H N proton in 1H NMR and FT-IR of 3a – 3d-AuNPs confirmed the formation of NHC-Au bond, and clearly showed that all acetyl groups, benzimidazolium heterocycle, and N -substituents maintained. XPS analyses revealed the presence of Au(0) and Au(I) in all Au@NHCs-sugar NPs. This result leads us to postulate that 3a – 3d-AuNPs exhibit a monolayer of Au(I) surrounding an Au(0) core. These designed 3a – 3d-AuNPs were studied for their self-assembly behavior, antibacterial activity against bacterium Xanthomonas citri susp. citri (Xcc), and catalytic activity towards the reduction of nitroarenes. All of them demonstrated strong antibacterial activity against Xcc with minimum inhibitory concentration value <0.03125 mg·mL−1. [ABSTRACT FROM AUTHOR]