Heteroleptic Coumarin-Based Silver(I) Complexes: Possible New Antimicrobial Agents

Heteroleptic coumarin-based silver(I) complexes with improved solubility profiles were synthesised using either triphenylphosphine or an <i>N</i>-heterocyclic carbene as adduct ligands, and were fully characterised using IR and NMR spectroscopy, elemental analysis, and, where possible, X...

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Main Authors: Erika Mooney, Brendan Twamley, Gordon Cooke, Emma Caraher, Matthias Tacke, Fintan Kelleher, Bernadette S. Creaven
Format: Article
Language:English
Published: MDPI AG 2024-12-01
Series:Molecules
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Online Access:https://www.mdpi.com/1420-3049/29/24/5917
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author Erika Mooney
Brendan Twamley
Gordon Cooke
Emma Caraher
Matthias Tacke
Fintan Kelleher
Bernadette S. Creaven
author_facet Erika Mooney
Brendan Twamley
Gordon Cooke
Emma Caraher
Matthias Tacke
Fintan Kelleher
Bernadette S. Creaven
author_sort Erika Mooney
collection DOAJ
description Heteroleptic coumarin-based silver(I) complexes with improved solubility profiles were synthesised using either triphenylphosphine or an <i>N</i>-heterocyclic carbene as adduct ligands, and were fully characterised using IR and NMR spectroscopy, elemental analysis, and, where possible, X-ray crystallography. The triphenylphosphine adducts formed well-resolved structures, where the oxyacetate ligands asymmetrically chelated the silver(I) ion in a bidentate chelating mode, and the silver(I) ion was also bound to two triphenylphosphine ligands. The solubility profile and photostability of the adducts were considerably improved compared to those of previously isolated simple coumarin silver(I) complexes. Analysis of the coumarin <i>N</i>-heterocyclic carbene(NHC) silver(I) adduct indicated that it likely formed as a complex aggregate species with an overall stoichiometry of 1:1:1 coumarin:Ag(I):NHC. The Kirby Bauer assay and broth microdilution assays were used to assess the silver(I) complexes’ and adducts’ antimicrobial activity against pathogenic strains of <i>Pseudomonas aeruginosa</i>, <i>Escherichia coli</i>, and MRSA. Interestingly, the formation of more soluble complexes did not increase the activity of the silver(I) complexes and, in effect, made them less effective antimicrobial agents, particularly against <i>Escherichia coli</i> and <i>Pseudomonas aeruginosa</i>, although they retained their activity against MRSA.
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spelling doaj-art-cf1722f4f20543e4b701da78c1e332702025-08-20T02:57:27ZengMDPI AGMolecules1420-30492024-12-012924591710.3390/molecules29245917Heteroleptic Coumarin-Based Silver(I) Complexes: Possible New Antimicrobial AgentsErika Mooney0Brendan Twamley1Gordon Cooke2Emma Caraher3Matthias Tacke4Fintan Kelleher5Bernadette S. Creaven6School of Chemical and BioPharmaceutical Sciences, Technological University Dublin, TU Dublin, Tallaght Campus, D24 FKT9 Dublin, IrelandSchool of Chemistry, Trinity College Dublin, D02 PN40 Dublin, IrelandSchool of Chemical and BioPharmaceutical Sciences, Technological University Dublin, TU Dublin, Tallaght Campus, D24 FKT9 Dublin, IrelandSchool of Chemical and BioPharmaceutical Sciences, Technological University Dublin, TU Dublin, Tallaght Campus, D24 FKT9 Dublin, IrelandUCD School of Chemistry, Science Centre South, University College Dublin, Belfield, D04 V1W8 Dublin, IrelandSchool of Chemical and BioPharmaceutical Sciences, Technological University Dublin, TU Dublin, Tallaght Campus, D24 FKT9 Dublin, IrelandCentre for AMR and One Health Research, Technological University Dublin, TU Dublin, Tallaght Campus, D24 FKT9 Dublin, IrelandHeteroleptic coumarin-based silver(I) complexes with improved solubility profiles were synthesised using either triphenylphosphine or an <i>N</i>-heterocyclic carbene as adduct ligands, and were fully characterised using IR and NMR spectroscopy, elemental analysis, and, where possible, X-ray crystallography. The triphenylphosphine adducts formed well-resolved structures, where the oxyacetate ligands asymmetrically chelated the silver(I) ion in a bidentate chelating mode, and the silver(I) ion was also bound to two triphenylphosphine ligands. The solubility profile and photostability of the adducts were considerably improved compared to those of previously isolated simple coumarin silver(I) complexes. Analysis of the coumarin <i>N</i>-heterocyclic carbene(NHC) silver(I) adduct indicated that it likely formed as a complex aggregate species with an overall stoichiometry of 1:1:1 coumarin:Ag(I):NHC. The Kirby Bauer assay and broth microdilution assays were used to assess the silver(I) complexes’ and adducts’ antimicrobial activity against pathogenic strains of <i>Pseudomonas aeruginosa</i>, <i>Escherichia coli</i>, and MRSA. Interestingly, the formation of more soluble complexes did not increase the activity of the silver(I) complexes and, in effect, made them less effective antimicrobial agents, particularly against <i>Escherichia coli</i> and <i>Pseudomonas aeruginosa</i>, although they retained their activity against MRSA.https://www.mdpi.com/1420-3049/29/24/5917silver(I)coumarinhybridantimicrobialphotostability
spellingShingle Erika Mooney
Brendan Twamley
Gordon Cooke
Emma Caraher
Matthias Tacke
Fintan Kelleher
Bernadette S. Creaven
Heteroleptic Coumarin-Based Silver(I) Complexes: Possible New Antimicrobial Agents
Molecules
silver(I)
coumarin
hybrid
antimicrobial
photostability
title Heteroleptic Coumarin-Based Silver(I) Complexes: Possible New Antimicrobial Agents
title_full Heteroleptic Coumarin-Based Silver(I) Complexes: Possible New Antimicrobial Agents
title_fullStr Heteroleptic Coumarin-Based Silver(I) Complexes: Possible New Antimicrobial Agents
title_full_unstemmed Heteroleptic Coumarin-Based Silver(I) Complexes: Possible New Antimicrobial Agents
title_short Heteroleptic Coumarin-Based Silver(I) Complexes: Possible New Antimicrobial Agents
title_sort heteroleptic coumarin based silver i complexes possible new antimicrobial agents
topic silver(I)
coumarin
hybrid
antimicrobial
photostability
url https://www.mdpi.com/1420-3049/29/24/5917
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AT gordoncooke heterolepticcoumarinbasedsilvericomplexespossiblenewantimicrobialagents
AT emmacaraher heterolepticcoumarinbasedsilvericomplexespossiblenewantimicrobialagents
AT matthiastacke heterolepticcoumarinbasedsilvericomplexespossiblenewantimicrobialagents
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