Pyrazolyl-functionalised Ag(i)-NHC complexes: synthesis, characterisation, antibacterial activity, and computational...

Area of Science:

• Medicinal Chemistry
• Organic Synthesis
• Computational Chemistry

Background:

• N-heterocyclic carbenes (NHCs) are versatile ligands in coordination chemistry and catalysis.
• Pyrazolyl-functionalised azolium salts and their metal complexes are explored for various biological activities.
• Developing new antibacterial agents is crucial due to rising antimicrobial resistance.

Purpose of the Study:

• To synthesize novel pyrazolyl-functionalised azolium salts and their corresponding silver(I)-NHC complexes.
• To evaluate the in vitro antibacterial activity of these synthesized compounds.
• To investigate the structure-activity relationship, including the effect of N-substituents and the benzimidazole core.

Main Methods:

• Synthesis of five pyrazolyl-functionalised azolium salts (1a-e) and their silver(I)-NHC complexes (2a-e).
• Characterization using spectroscopic (e.g., NMR, IR) and analytical techniques.
• In vitro antibacterial assays against a broad spectrum of bacterial strains.
• Computational studies including DFT calculations and SWISSADME predictions.

Main Results:

• All synthesized compounds (salts and complexes) were successfully characterized.
• The silver(I)-NHC complexes exhibited in vitro antibacterial activity.
• Compound 2c, with a benzyl N-substituent on the benzimidazole core, displayed the highest potency, comparable to the standard drug neomycin.
• DFT and SWISSADME analyses suggested enhanced activity for benzimidazole derivatives and highlighted the role of the N-benzyl group.

Conclusions:

• Pyrazolyl-functionalised silver(I)-NHC complexes represent a promising class of antibacterial agents.
• The N-benzyl substituent and the benzimidazole scaffold significantly contribute to enhanced antibacterial efficacy.
• Further research into these compounds could lead to the development of new therapeutic strategies against bacterial infections.