Synthesis, characterization and catalytic properties of an N-heterocyclic carbene palladium-based complex

Razali

et al. 2014

A series of new benzimidazolium salts as N-heterocyclic carbene (NHC) precursors has been synthesized. Reactions of these salts with Ag 2 O with varying metal-to-salt ratio facilitate the formation of a series of new binuclear and mononuclear Ag(I)-NHC complexes. All compounds were characterized using physicochemical and spectroscopic techniques. Single-crystal X-ray diffraction study reveals a binuclear structure for one of the complexes and a mononuclear one for two others. These complexes exist as cationic Ag(I)-NHC complexes with the chelation of carbene carbons to the silver centre in an almost linear manner. The compounds were screened for their anti-bacterial activities against Staphylococcus aureus (ATCC 12600) as a Gram-positive bacterium and Escherichia coli (ATCC 25922) as a Gram-negative bacterium. The results show that both bacteria appear markedly inhibited. Furthermore, the results suggest the possibility of steric variation as a modulation of the anti-bacterial activities. The nuclease activities of the compounds were assessed using gel electrophoresis and the results indicate that these complexes can cleave or degrade DNA and RNA via a non-oxidative mechanism.

Section: Resultssupporting

confidence: 87%

mentioning

confidence: 99%

Benzimidazole‐based silver(I)–N‐heterocyclic carbene complexes as anti‐bacterials: synthesis, crystal structures and nucleic acids interaction studies

Asekunowo

Razali

et al. 2014

“…The multiplets in the range δ 7.41–8.19 and 1.3–4.2 are due to the resonance of aromatic and aliphatic protons. Spectra also evidenced a characteristic downfield resonance in the range δ 9.87–10.06 corresponding to the NCHN proton, indicating the successful formation of benzimidazolium salts . This down‐field shift of the NCHN protons is due to their deshielding by two adjacent electronegative nitrogen atoms that withdraw higher electron density from around the benzimidazolium proton compared to other protons.…”

Section: Resultsmentioning

confidence: 97%

Nitrile‐functionalized Hg(II)‐ and Ag(I)‐N‐heterocyclic carbene complexes: synthesis, crystal structures, nuclease and DNA binding activities

Budagumpi

Choo

et al. 2012

Various nitrile‐functionalized benzimidazol‐2‐ylidene carbene complexes of Hg(II) and Ag(I) were synthesized by the interaction of 1‐benzyl/1‐butyl‐3‐(cyano‐benzyl)‐3 H‐benzimidazol‐1‐ium mono/dihexafluorophosphate with Hg(OAc)2/Ag2O in acetonitrile. Two of the benzimidazolium salts were structurally characterized by single crystal X‐ray diffraction technique. Structures of reported compounds were characterized by 1 H, 13C NMR, FT‐IR, UV–visible spectroscopic techniques, and molar conductivity and elemental analyses. For bis‐benzimidazolium salt, dinuclear Hg(II)– and Ag(I)–carbene complexes were obtained. Nuclease activity and binding interactions of the synthesized benzimidazolium salts and their Ag(I)–carbene complexes with DNA were studied using agarose gel electrophoresis and, absorption spectroscopy and viscosity measurements, respectively. Ag(I)–carbene complexes showed higher DNA binding activity compared to their respective benzimidazolium salts. However, a benzimidazolium salt and two of the Ag(I) complexes showed remarkably higher nuclease activity both, in the presence and absence of an oxidizing agent. Copyright © 2012 John Wiley & Sons, Ltd.

“…Both bromide and hexafluorophosphate salts were characterized by NMR spectral method over the range δ 0–12. In the 1 H NMR spectra of the salts, a characteristic downfield resonance in the range δ 10.18–10.31 corresponding to the NCHN proton indicated the successful formation of benzimidazolium salts . Spectra also evidenced the presence of a set of peaks in the range δ 7.4–7.9 and 5.7–6.1, ascribed to the resonance of aromatic and benzyl protons, respectively.…”

Section: Resultsmentioning

confidence: 98%

Binuclear meta‐xylyl‐linked Ag(I)‐N‐heterocyclic carbene complexes of N‐alkyl/aryl‐alkyl‐substituted bis‐benzimidazolium salts: synthesis, crystal structures and in vitro anticancer studies

Iqbal

Budagumpi

et al. 2013

Salts of meta‐xylyl‐linked N‐ethyl/n‐butyl/benzyl‐substituted bis‐benzimidazolium having hexafluorophosphate counterions have been synthesized. The corresponding binuclear Ag(I)‐N‐heterocyclic carbene complexes were prepared by the reaction of Ag2O. The N‐heterocyclic carbene (NHC) ligand precursor 7 and Ag(I)–NHC complexes 10 and 11 have been structurally characterized by single‐crystal X‐ray diffraction technique. All of the reported compounds have been tested for their anticancer activity using human colorectal (HCT 116) cancer cell lines. Sterically varied benzimidazolium salts displayed significant activity against HCT 116 cell line, yielding IC50 values in the range 0.1–19.4 µ m, while Ag(I)–carbene complexes showed exceptionally good activity (0.2–1.3 µ m) against tested cancer cell lines. Copyright © 2013 John Wiley & Sons, Ltd.