Ru Nanoparticles Ligated by an N-Heterocyclic Carbene Derived from Uracil Nucleoside as Selective Antimicrobial Agents

Metal nanoparticles (MNPs) effectively combat pathogens due to their nonspecific toxicity, reducing the chance of bacterial resistance. Natural-based stabilizing ligands enhance the stability and targeting of MNPs while minimizing toxicity to human cells. In this context, ura-NHC-stabilized Ru NPs (<b>Ru@ura-NHC</b>) have been successfully synthesized following an organometallic approach, employing Ru(COD)(COT) as the metal precursor and, for the first time, a zwitterionic uracil-6-yl-imidazolium betaine (<b>ura-zwt</b>) as the NHC precursor. The mesomeric properties of <b>ura-zwt</b> enabled its use as an air-stable NHC precursor for the one-pot synthesis of <b>Ru@ura-NHC</b> with 100% atom economy and without byproduct formation. A combined theoretical/experimental study was conducted to investigate the coordination of the uracil-based NHC onto the Ru surface, indicating that the coordination of the neutral form (<b>ura-NHC</b>) is preferred over the zwitterionic form (<b>ura-zwt</b>). Evaluation of the antimicrobial properties of <b>Ru@ura-NHC</b> revealed that the coated Ru NPs exhibit selective activity against <i>Staphylococcus aureus</i>, which is beneficial as it minimizes off-target effects and reduces selective pressure for resistance.