Synthesis, structures, antimicrobial activity and biosafety evaluation of pyridine-2-formaldehyde- N -susbtituted-thiosemicarbazonates of copper( ii )

• Published in: New journal of chemistry 2018, Vol.42 (19), p.15879-15894
• Main Authors: Kaushal, Mani, Lobana, Tarlok S., Nim, Lovedeep, Kaur, Jaskamal, Bala, Ritu, Hundal, Geeta, Arora, Daljit S., Garcia-Santos, Isabel, Duff, Courtney E., Jasinski, Jerry P.
• Format: Article
• Language: English
• Subjects: Acetonitrile; Antiinfectives and antibacterials; Antimicrobial agents; Coordination compounds; Copper; Copper compounds; Crystallography; Dichloromethane; E coli; Formaldehyde; Halides; Infrared spectroscopy; Klebsiella; Mass spectrometry; Microorganisms; Nitrogen; Pathogens; Salmonella; Single crystals; Substitutes; Toxicity; Yeast
• ISSN: 1144-0546; 1369-9261
• DOI: 10.1039/C8NJ03619E

Pyridine-2-formaldehyde- N 1 -substituted-thiosemicarbazones {(C 5 H 4 N 4 )HC 2 N 3 –N 2 (H)–C 1 (S)N 1 HR} (abbrev. HL 1 -R: R = Me, Et, Ph) with copper( i ) halides in an acetonitrile–dichloromethane mixture (1 : 1, v/v) have yielded a novel series of Cu II complexes with a central coordination core: [Cu II X(N,N,S-L 1 -R)] (R = Me, Et, Ph: X = I, 1–3 ; Br, 4–6 , Cl, 7–9 ), which have been characterized with the help of analytical data, IR, UV-visible and ESR spectroscopy, ESI-mass spectrometry and single crystal X-ray crystallography. The thio-ligands coordinate to Cu II as anions (L 1 -R) − through pyridyl nitrogen-N 4 , azomethine nitrogen-N 3 and thiolato sulfur and Cu II is further bonded to iodide, bromide or chloride. In order to explore their bio-activity, complexes ( 1–9 ) as well as the previously reported Cu II complexes of 2-benzoylpyridine- N -substituted thiosemicarbazones {(C 5 H 4 N 4 )(C 6 H 5 )–C 2 N 3 –N 2 (H)–C 1 (S)–N 1 HR; HL 2 -R}, namely, [Cu II X(N,N,S-L 2 -R)] (R = Me, Et, Ph: X = I, 10–12 ; Br, 13–15 ; Cl, 16–18 ), have been evaluated for their antimicrobial potential against different microbial strains. The microbial strains investigated are Staphylococcus aureus (MTCC740), Klebsiella pneumoniae (MTCC530), Shigella flexneri (MTCC1457), Salmonella typhimurium 1 (MTCC98), Salmonella typhimurium 2 (MTCC1251), Escherichia coli (MTCC119), Staphylococcus epidermidis (MTCC435), methicillin resistant Staphylococcus aureus (MRSA) and a yeast culture Candida albicans (MTCC227). Several complexes tested have shown high antimicrobial activity; specifically, against methicillin resistant Staphylococcus aureus, Staphylococcus epidermidis and Salmonella typhimurium 2; the activity is found to be high at low minimum inhibitory concentration (MIC) values as compared to that of the standard Gentamicin. Using MTT cytotoxicity assay {MTT = 3-[(4,5-dimethylthiazol-2-yl)-2,5-diphenyl]tetrazolium bromide}, complexes tested were found to be biosafe with high cell viability (90–98%).