Picolyl and benzyl functionalized biphenyl NHC carbenes and their silver complexes: Sigma donating and antimicrobial properties

Picolyl and benzyl linked biphenyl NHC ligands L(1)H(2)Br(2)to (LH2Br2)-H-4(L1-L4 ) and their silver-N-heterocyclic carbene complexes [AgL2]PF6(1), [AgL3]PF6(2), and [AgL4]PF6(3) were synthesized and characterized. Sigma donating properties of the NHC ligands were calculated by proton-coupled C-13-NMR spectroscopy. Silver-N-heterocyclic carbene complexes were synthesized via in situ deprotonation of azolium salts with silver(I) oxide under the light exclusion. One of the silver complexes, [AgL3]PF6(2), was confirmed by a single crystal XRD. All the ligands and silver-N-heterocyclic carbene complexes were investigated for antimicrobial activity against the bacterial strains grown from human clinical isolates. The NHC ligands and Ag-NHC complexes showed better antimicrobial activity than the reported phenyl-substituted NHC precursors and their Silver-NHC complexes against Gram-positive Staphylococcus aureus and Gram-negative Pseudomonas aeruginosa bacterial strains. (C) 2021 Elsevier B.V. All rights reserved.

Automated summary

Picolyl and benzyl linked biphenyl NHC ligands and their silver-N-heterocyclic carbene complexes were synthesized and characterized, showing better antimicrobial activity against Staphylococcus aureus and Pseudomonas aeruginosa bacterial strains compared to reported precursors.