Silver(I)‐N‐heterocyclic carbene complexes of bis‐imidazol‐2‐ylidenes having different aromatic‐spacers: synthesis, crystal structure, and in vitro antimicrobial and anticancer studies

Abstract

A series of Ag(I) complexes (6-9) derived from imidazol-2-ylidenes was synthesized by reacting Ag 2 O with an o-, m-, p-xylyl or 1,3,5-triazine-linked imidazolium salts (1-4) and then characterizing these using various spectro-analytical techniques. Additionally, triazine-linked bis-imidazolium salt 5 was characterized using the single-crystal X-ray diffraction method. Complexes 6-9 were formed from the N-heterocyclic carbene ligand precursors 1-3 as PF 6 salts in good yields. Conversely, salt 5 does not form Ag(I) complex even under various reaction conditions. Using ampicillin as a standard, complexes 6-9 were tested against bacteria strains Escherichia coli and Staphylococcus aureus as Gram-negative and Gram-positive bacteria, respectively, showing potent antimicrobial activities against the tested bacteria even at minimum inhibition concentration and bacterial concentration levels. Furthermore, the potential anticancer activities of the reported complexes were evaluated against the human colorectal cancer (HCT 116) cell lines, using 5-fluorouracil as a standard drug. The highest anticancer activities were observed for complex 8 with an IC 50 value of 3.4 mM, whereas the lowest was observed for complex 9 with an IC 50 value of 18.1 mM. Copyright

Benzimidazolium-based novel silver N-heterocyclic carbene complexes: synthesis, characterisation and in vitro antimicrobial activity

“…Ag + in low concentrations is non-toxic to humans, therefore a compound that releases Ag + to the environment in a steady rate make an effective antimicrobial agent [2][3][4][5][6][7][8][9][10] . The effectiveness of a silver complex as an antimicrobial agent depends on the bioavailability of Ag + when the compound is solubilised.…”

“…Many factors can influence this bioavailability of Ag + including the solubility and ionisation of the compound, the delivery route and the presence of anions in the environment such as chloride, bromide and sulphide [1][2][3]7 . It has also been well established that silver N-heterocyclic carbenes (Ag-NHCs) are a class of organometallic compounds that are stable in the presence of air or moisture; the release of Ag + to the environment is slow and consistent 4,5,7,8 . As Ag-NHC complexes can be easily and efficiently synthesised, the characterisation of this class of compounds has generated considerable interest in order to determine their effectiveness as antimicrobial agents.…”

N -Heterocyclic Carbene Metal Complexes as Bio-Organometallic Antimicrobial and Anticancer Drugs

“…44d >50 KB-V1/Vbl [113] 44d >50 HF [113] 45a 8.7 ± 1.5 Caki-1 [114] 45b 4.6 ± 0.1 Caki-1 [114] 45c 5.5 ± 0.5 Caki-1 [114] 45d 35 ± 1 Caki-1 [114] 45e 42 ± 4 Caki-1 [114] 45f 29 ± 1 Caki-1 [114] 45g 23 ± 1 Caki-1 [114] 45h -Caki-1 [114] 45i 100 ± 2 Caki-1 [114] 45a 4.7 ± 0.5 MCF-7 [114] 45b 2.1 ± 0.8 MCF-7 [114] 45c 3.4 ± 0.6 MCF-7 [114] 45d 15 ± 2 MCF-7 [114] 45e 25 ± 7 MCF-7 [114] 45f 14 ± 3 MCF-7 [114] 45g 13 ± 1 MCF-7 [114] 45h -MCF-7 [114] 45i 21 ± 5 MCF-7 [114] 46 44 ± 3 Caki-1 [114] 46 24 ± 3 MCF-7 [114] 60 18.1 HCT 116 [118] 61 3.4 HCT 116 [118] 62 14.6 HCT 116 [118] 63 11.5 HCT 116 [118] 64a 1.7 ± 0.4 HCT 116 [119] 64b 6.0 ± 0.7 HCT 116 [119] 64c 1.7 ± 0.2 HCT 116 [119] 64d 27.2 ± 1.1 HCT 116 [119] 64e 6.0 ± 0.2 HCT 116 [120] 64f 14.0 ± 0.6 HCT 116 [120] 64g 4.0 ± 0.2 HCT 116 [120] 64g 0.9 ± 0.4 MCF-7 [120] [109] 45a S. aureus 0.44 μmol 5 mm [114] 45b S. aureus 0.44 μmol 2 mm [114] 45c S. aureus 0.44 μmol 3 mm [114] 45d S. aureus 0.44 μmol 4 mm [114] 45e S. aureus 0.44 μmol 3 mm [114] 45f S. aureus 0.44 μmol 5 mm [114] 45g S. a...…”

“…aureus 3 μl 5 ± 1 mm [116] 55 S. aureus 6 μl 7 ± 1 mm [116] 55 S. aureus 9 μl 8 ± 1 mm [116] 55 S. aureus 12 μl 9 ± 1 mm [116] 56 S. aureus 100 μg/ml 13.7 ± 1.2 mm [117] 56 E. coli 100 μg/ml 12.4 ± 1.5 mm [117] 57 S. aureus 100 μg/ml 26.0 ± 0.8 mm [117] 57 E. coli 100 μg/ml 25.6 ± 0.5 mm [117] 58 S. aureus 100 μg/ml 27.5 ± 2.0 mm [117] 58 E. coli 100 μg/ml 27.0 ± 0.7 mm [117] 59 S. aureus 100 μg/ml 16.0 ± 0.4 mm [117] 59 E. coli 100 μg/ml 14.0 ± 0.7 mm [117] 60 E. coli 3 μl 10 ± 1 mm [118] 60 E. coli 6 μl 12 ± 1 mm [118] 60 E. coli 9 μl 14 ± 1 mm [118] 60 E. coli 12 μl 14 ± 1 mm [118] 60 S. aureus 3 μl 10 ± 1 mm [118] 60 S. aureus 6 μl 12 ± 0 mm [118] 60 S. aureus 9 μl 15 ± 0 mm [118] 60 S. aureus 12 μl 15 ± 0 mm [118] 61 E. coli 3 μl 11 ± 1 mm [118] 61 E. coli 6 μl 12 ± 1 mm [118] 61 E. coli 9 μl 14 ± 1 mm [118] 61 E. coli 12 μl 14 ± 1 mm [118] 61 S. aureus 3 μl 10 ± 1 mm [118] 61 S. aureus 6 μl 12 ± 0 mm [118] 61 S. aureus 9 μl 14 ± 1 mm [118] 61 S. aureus 12 μl 14 ± 1 mm [118] 62 E. coli 3 μl 13 ± 1 mm [118] 62 E. coli 6 μl 15 ± 1 mm [118] 62 E. coli 9 μl 17 ± 1 mm [118] 62 E. coli 12 μl 18 ± 1 mm [118] 62 S. aureus 3 μl 15 ± 0 mm [118] 62 S. aureus 6 μl 16 ± 1 mm [118] 62 S. aureus 9 μl 17 ± 1 mm [118] 62 S. aureus 12 μl 20 ± 1 mm [118] 63 E. coli 3 μl 8 ± 0 mm [118] 63 E. coli 6 μl 9 ± 1 mm...…”

Synthesis and Cytotoxicity of Dinuclear Silver(I)-N-Heterocyclic Carbene Complexes

“…Silver(I)-NHC complexes have shown excellent anticancer results against various types of cancerous cell lines [7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23]. Silver containing organometallic compounds, other than silver(I)-NHC complexes, have also shown significant biological activities [23,24].…”