NOPR Collection:

Synthesis and characterization of novel chelation-free Zn(II)-azole complexes: Evaluation of antibacterial, antioxidant and DNA binding activity

2020-06-17T08:28:22Z

Title: Synthesis and characterization of novel chelation-free Zn(II)-azole complexes: Evaluation of antibacterial, antioxidant and DNA binding activity Authors: Nandanwar, Sondavid K; Borkar, Shweta B; Wijaya, Bryan Nathanael; Bayarra, Enkhnaran; Piad, Lei Lottice Anne; Jin, QiuLi; Tiara, Celine Sheila; Kim, Hak Jun; Tarte, Naresh H. Abstract: Here, we synthesized novel chelation-free Zn(II)-complexes (1-3) [ZnCl₂L₂] of monodentate ligands with L = 2-isopropylimidazole (L1), 2-methylbenzimidazole (L2), and 2-methylbenzoxazole (L3) and evaluated their antibacterial, antioxidant and DNA binding activities. The chelation-free properties of these coordination complexes were confirmed by UV-visible spectroscopy, ¹H NMR spectroscopy, single X-ray crystallography and elemental analysis. Complexes 1-3 exhibited substantial antibacterial activity against all antibiotic susceptible bacteria within a concentration range of 100-200 µg/ml while free ligands L1 and L2 exhibited weak antibacterial activity considerably concentration above 200 µg/ml. Also, both complexes 2 and 3 were twice more active against methicillin-resistant Staphylococcus aureus (MRSA) than complex 1. Furthermore, we found that complexes 1-3 showed DNA binding activity with E. coli plasmid DNA and calf thymus DNA, which may be a plausible mechanism for their antibacterial activity. We also investigated the antioxidant activity of complexes 1-3 and found that complex 2 exhibited potential antioxidant activity compared to complexes 1 and 3. All these results suggest that the chelation-free Zn(II)-complexes can be the future candidates for more advance biological studies. Page(s): 589-597

Copper(I) complexes with N-(2-quinolinylmethylene)-1, 5-dimethyl- 2-phenyl-1-pyrazole-3-(2H)-one and phosphine as ligands: Effective catalyst for Sonogashira cross-coupling reaction

2020-06-17T08:24:03Z

Title: Copper(I) complexes with N-(2-quinolinylmethylene)-1, 5-dimethyl- 2-phenyl-1-pyrazole-3-(2H)-one and phosphine as ligands: Effective catalyst for Sonogashira cross-coupling reaction Authors: Chavan, S. S.; Devkule, S. S. Abstract: A new series of copper(I) complexes of the type [Cu(L)(PPh₃)₂]X (1a-c) and [Cu(L)(dppe)]X (2a-c) have been prepared by the reaction of Cu(MeCN)₄]X (where X = ClO, BF and PF) with N-(2-quinolinylmethylene)-1,5-dimethyl-2-phenyl-1-pyrazole-3-(2H)-one (L) in presence of triphenylphosphine (PPh₃) or 1,2-bis(diphenylphosphino)ethane (dppe) as an ancillary ligand. The UV-visible spectra indicate that, the ancillary phosphine ligands significantly perturb the MLCT state of copper(I) complexes. The thermally stable 1a-c and 2a-c complexes exhibit quasireversible redox behaviour corresponding to Cu(I)/Cu(II) couple. All complexes are tested as catalyst for Sonogashira cross-coupling of phenylacetylene with aryl iodide. The results show that all complexes worked as an effective catalyst at low temperature yielding substituted aryl alkynes as a product. The nature of phosphine ligands and size of counter anions shows marked effect on catalytic properties of all the complexes. Page(s): 598-607

Synthesis, spectral studies and antibacterial activity of iron(III) complexes with hydrazone functionalized ligands: X-Ray structure determination of a novel five coordinate complex containing labile ligands

2020-06-17T08:58:57Z

Title: Synthesis, spectral studies and antibacterial activity of iron(III) complexes with hydrazone functionalized ligands: X-Ray structure determination of a novel five coordinate complex containing labile ligands Authors: Kasimbi, Dudekula; Reddy, Katreddi Hussain; Devanna, N. Abstract: Iron(III) complexes having general formula FeLCl₂ [where, L = 2-acetylpyridine acetoylhydrazone (APAH), 2-acetylpyridine benzoylhydrazone (APBH), 2-acetylthiophene acetoylhydrazone (ATAH), and 2-acetythiophene benzoylhydrazone (ATBH)] have been synthesized and characterized based on molar conductivity, electronic and IR spectroscopy. The structure of iron(III) complex with APBH ligand is determined using single crystal X-ray crystallography. The complex crystallizes in monoclinic space group P21/n with a = 7.8490(6) Å, b = 15.1018(11) Å, c = 13.2263(10) Å, α = 90°, β=100.183(3)°, γ = 90°, V = 1543.1(2) Å³ and Z = 4 with central Fe(III) ion coordinated by one tridentate APBH ligand. The iron is involved in 5-coordinate bonding with one organic (hydrazone) unit and two labile chloride ligands. The ligand acts as NNO–tridentate donor system. Iron is coordinated to pyridine ring nitrogen, azomethine nitrogen and benzoyl oxygen atoms and the two chloride ligands bind with metal completing distorted square pyramidal structure. The ligands and iron complexes are screened for their anti-bacterial activities against Pseudomonas aureoginos and Bacillus cereus. Among ligands, acetoyl hydrazones show more activity than the corresponding benzoyl hydrazones. The hydrazones having a methyl/ and pyridine groups show higher antibacterial activity. The iron complexes show higher activity than the metal free ligands. Page(s): 608-615

Flexible modified plastic strips coated polyaniline/graphene composite for electrochemical biosensors

2020-06-17T07:29:11Z

Title: Flexible modified plastic strips coated polyaniline/graphene composite for electrochemical biosensors Authors: Sangeetha, D. N.; Pooja, H; Bhandary, Savisha; Shetty, Yashaswini; Subashchandrabose, Raghu; Selvakumar, M. Abstract: Polyaniline(PANI)/graphene modified flexible, disposable polyester overhead projector (OHP) strips for non-enzymatic detection of ascorbic acid (AA) and uric acid (UA) is demonstrated in the current work. The deposition of PANI on the 3-aminopropyltrimethoxy silane (APTMS) modified OHP have been optimized through electrochemical impedance spectroscopy. Graphene is coated on another end. The PANI/graphene coating is confirmed through scanning electron microscopy. UA and AA detection have been carried out using the standard electrochemical techniques like cyclic voltammetry and chronoamperometry. The study reveals that the composite of PANI/graphene exhibits good sensing towards the detection of UA and AA. During the detection of UA and AA, PANI/graphene has showed enhanced current density with quick response and a linear concentration range of 10 to 300 μM for UA and 30 to 80 μM for AA. These flexible sensor strips may be of great potential in real-time UA and AA detection. Page(s): 616-624