TY - JOUR
T1 - Chlorido-containing ruthenium(II) and iridium(III) complexes as antimicrobial agents
AU - Pandrala, Mallesh
AU - LI, Fangfei
AU - Feterl, Marshall
AU - Mulyana, Yanyan
AU - Warner, Jeffrey M.
AU - Wallace, Lynne
AU - Richard Keene, F.
AU - Collins, J. Grant
N1 - Funding Information:
The Australian Research Council is thanked for financial support and F.L. thanks the China Scholarship Council (CSC) for a PhD scholarship.
Publisher Copyright:
© The Royal Society of Chemistry 2013
PY - 2013/1/29
Y1 - 2013/1/29
N2 - A series of polypyridyl-ruthenium(II) and -iridium(III) complexes that contain labile chlorido ligands, [{M(tpy)Cl}2{μ-bbn}]2/4+ {Cl-Mbbn; where M = Ru or Ir; tpy = 2,2′:6′,2′′-terpyridine; and bbn = bis[4(4′-methyl-2,2′-bipyridyl)]-1,n-alkane (n = 7, 12 or 16)} have been synthesised and their potential as antimicrobial agents examined. The minimum inhibitory concentrations (MIC) and minimum bactericidal concentrations (MBC) of the series of metal complexes against four strains of bacteria – Gram positive Staphylococcus aureus (S. aureus) and methicillin-resistant S. aureus (MRSA), and Gram negative Escherichia coli (E. coli) and Pseudomonas aeruginosa (P. aeruginosa) – have been determined. All the ruthenium complexes were highly active and bactericidal. In particular, the Cl-Rubb12 complex showed excellent activity against all bacterial cell lines with MIC values of 1 μg mL−1 against the Gram positive bacteria and 2 and 8 μg mL−1 against E. coli and P. aeruginosa, respectively. The corresponding iridium(III) complexes also showed significant antimicrobial activity in terms of MIC values; however and surprisingly, the iridium complexes were bacteriostatic rather than bactericidal. The inert iridium(III) complex, [{Ir(phen)2}2{μ-bb12}]6+ {where phen = 1,10-phenanthroline) exhibited no antimicrobial activity, suggesting that it could not cross the bacterial membrane. The mononuclear model complex, [Ir(tpy)(Me2bpy)Cl]Cl2 (where Me2bpy = 4,4′-dimethyl-2,2′-bipyridine), was found to aquate very rapidly, with the pKa of the iridium-bound water in the corresponding aqua complex determined to be 6.0. This suggests the dinuclear complexes [Ir(tpy)Cl}2{μ-bbn}]4+ aquate and deprotonate rapidly and enter the bacterial cells as 4+ charged hydroxo species.
AB - A series of polypyridyl-ruthenium(II) and -iridium(III) complexes that contain labile chlorido ligands, [{M(tpy)Cl}2{μ-bbn}]2/4+ {Cl-Mbbn; where M = Ru or Ir; tpy = 2,2′:6′,2′′-terpyridine; and bbn = bis[4(4′-methyl-2,2′-bipyridyl)]-1,n-alkane (n = 7, 12 or 16)} have been synthesised and their potential as antimicrobial agents examined. The minimum inhibitory concentrations (MIC) and minimum bactericidal concentrations (MBC) of the series of metal complexes against four strains of bacteria – Gram positive Staphylococcus aureus (S. aureus) and methicillin-resistant S. aureus (MRSA), and Gram negative Escherichia coli (E. coli) and Pseudomonas aeruginosa (P. aeruginosa) – have been determined. All the ruthenium complexes were highly active and bactericidal. In particular, the Cl-Rubb12 complex showed excellent activity against all bacterial cell lines with MIC values of 1 μg mL−1 against the Gram positive bacteria and 2 and 8 μg mL−1 against E. coli and P. aeruginosa, respectively. The corresponding iridium(III) complexes also showed significant antimicrobial activity in terms of MIC values; however and surprisingly, the iridium complexes were bacteriostatic rather than bactericidal. The inert iridium(III) complex, [{Ir(phen)2}2{μ-bb12}]6+ {where phen = 1,10-phenanthroline) exhibited no antimicrobial activity, suggesting that it could not cross the bacterial membrane. The mononuclear model complex, [Ir(tpy)(Me2bpy)Cl]Cl2 (where Me2bpy = 4,4′-dimethyl-2,2′-bipyridine), was found to aquate very rapidly, with the pKa of the iridium-bound water in the corresponding aqua complex determined to be 6.0. This suggests the dinuclear complexes [Ir(tpy)Cl}2{μ-bbn}]4+ aquate and deprotonate rapidly and enter the bacterial cells as 4+ charged hydroxo species.
UR - https://www.scopus.com/record/display.uri?eid=2-s2.0-84874820653&origin=inward
U2 - 10.1039/C3DT32775B
DO - 10.1039/C3DT32775B
M3 - Journal article
SN - 1477-9226
VL - 42
SP - 4686
EP - 4694
JO - Dalton Transactions
JF - Dalton Transactions
IS - 13
ER -