Localized canting of spins structure in the spinel oxide system: ZnzTizFe2−x−zCrx−zCoO4

The spinel oxide system Zn_zTi_zFe_2−x−zCr_x−zCoO₄; z=x²; x=0.60, 0.65, 0.70 and 0.80, was studied using neutron diffraction technique, low field DC magnetization measurements (ZFC–FC measurements), magnetic hysterisis, Mössbauer spectroscopy and low field AC susceptibility measurements. All the compositions show significantly less B-site magnetic moments at 10 K temperature derived from neutron diffraction data than the free ions site moments deduced assuming collinear arrangement of spins. This combined with some other features seen in the low temperature neutron diffraction patterns suggest localized canting of spins (LCS) type of magnetic ordering in the present system where a long range order of longitudinal component of moments co-exists along with totally disordered transverse component of moments. The conclusion is also supported by the features seen in the other measurements. The magnetic moments derived from 10 K neutron diffraction data are explained using the LCS approach for different exchange integrals ratios.     

Design,synthesis, evaluation,and molecular dynamic simulation of triclosan mimic diphenyl ether derivatives as antitubercular and antibacterial agents

In the present work, we have explored triclosan mimic diphenyl ether derivatives as inhibitors of Mycobacterium tuberculosis enoyl acyl carrier protein reductase (InhA) using a structure-based drug design approach. The virtual library of diphenyl ethers was designed and compounds with acceptable absorption, distribution, metabolism, excretion, and toxicity properties were docked. The compounds with higher dock score (5a-g) than triclosan were synthesized, characterized, and evaluated for in vitro antitubercular activity against Mycobacterium tuberculosis H37Rv. Among the synthesized compounds, compounds 5f and 5c appeared to be the most promising with minimum inhibitory concentration of 18 μM and 36 μM respectively. The molecular dynamics simulation study of the most active compound 5f and triclosan was performed, which correlates with its activity in comparison with triclosan. All the compounds were further evaluated for cytotoxicity studies against Vero, and HepG2 were found to be safe. Furthermore, compound 5f was evaluated for in vitro cytotoxicity against mouse macrophage cell lines (RAW 264.7), and the study indicated its safety in eukaryotes at 50-μM concentration. In addition, compounds 5a-g were also screened for their in vitro antibacterial activity against two gram-positive and two gram-negative bacteria by resazurin-based microtiter dilution assay method. Among the synthesized compounds, 5f and 5b appeared to be promising, against various gram-positive and gram-negative microorganisms, indicating its broad-spectrum potential.

     

Zeolite-Y entrapped bivalent transition metal complexes as hybrid nanocatalysts: density functional theory investigation and catalytic aspects

The intriguing research toward the exploitation of zeolite-Y-based hybrid nanocatalysts for catalytic oxidation reactions has been growing significantly. In the present investigation, we describe the synthesis of zeolite-Y entrapped transition metal complexes of the general formulae [M(SFCH)·xH₂O]-Y (where, M = Mn, Fe, Co, Ni (x = 3) and Cu (x = 1)); H₂SFCH = (E)-N′-(2-hydroxybenzylidene)furan-2-carbohydrazide]. These nanocatalysts have been characterized by various physicochemical techniques. Density functional theory calculations are performed to address the relaxed geometry, bond angle, bond length, dihedral angle, highest occupied molecular orbital (HOMO)–lowest unoccupied molecular orbital (LUMO) energy gap, and electronic density of states of H₂SFCH ligand and their neat transition metal complexes. The observed HOMO–LUMO gap and the Fermi energy is higher for Cu(II) complexes, which demonstrates the better catalytic activity of this nanocatalyst. The catalytic activity was performed in liquid-phase oxidation of cyclohexane using hydrogen peroxide as oxidant to give cyclohexanone (CyONE) and cyclohexanol (CyOL). Among them, [Cu(SFCH)·H₂O]-Y catalyst has the highest selectivity toward CyONE (84.5%).     

Synthesis of novel biaryl 2-benzimidazoles and 2-benzothiazoles

Herein, we describe the synthesis of the novel 4-(1H-benzo[d]imidazol-2-yl)isoxazol-5-amine (7) and 4-(1H-benzo[d]thiazol-2-yl)isoxazol-5-amine scaffolds (8). Initial attempts following literature procedures for the synthesis of similar compounds did not yield the desired product. Instead we obtained the ring-opened adduct 2-(1H-benzo[d]imidazol-2(3H)-ylidene)-2-cyanoacetamide (5). We were able to modify reaction conditions and successfully synthesize the desired product. We also describe a convenient one-pot microwave-assisted relay reaction for the synthesis of novel and reported 2-substituted benzimidazoles and benzothiazoles from inexpensive, commercially available reagents, 2-benzothiazole acetonitrile (2) and 2-benzimidazole acetonitrile (1). In all cases, good yields of products were obtained and reaction times were significantly reduced.     

Synthesis, spectral investigation and thermal aspects of coordination polymeric chain assemblies of some transition metal ions with bis-pyrazolones

A few coordination chain polymeric assemblies of the type [M(SB)(H(2)O)(2)](n).xH(2)O or [VO(SB)(H(2)O)](n).H(2)O [where M=Mn(II), Cu(II) and Zn(II), x=1; Co(II) and Ni(II) x=2, H(2)SB=(4Z,4'Z)-4,4'-(2,2'-(4,4'-methylenebis(4,1-phenylene)bis(azanediyl))bis(1-hydroxy ethan-2-yl-1-ylidene))bis(3-methyl-1-phenyl-1H-pyrazol-5(4H)-one)] have been investigated. Structural and spectroscopic properties have been studied on the basis of elemental analyses, infrared spectra, (1)H and (13)C NMR spectra, electronic spectra, magnetic measurements and thermo gravimetric analyses. FT-IR, (1)H and (13)C NMR studies reveal that the ligand (H(2)SB) exists in the tautomeric enol form in both the states with intramolecular hydrogen bonding. Magnetic moment and reflectance spectral studies reveal that an octahedral geometry has been assigned to all the prepared coordination polymers. The kinetic parameters such as order of reaction (n) and the energy of activation (E(a)) have been reported using Freeman-Carroll method. The pre-exponential factor (A), the activation entropy (DeltaS(#)), the activation enthalpy (DeltaH(#)) and the free energy of activation (DeltaG(#)) have been calculated.     

Assessment of the metabolic profile in Type 2 diabetes mellitus and hypothyroidism through proton MR spectroscopy

The metabolic changes in the brain of patients affected with Type 2 diabetes mellitus (DM) alone, both Type 2 DM and hypothyroidism and hypothyroidism only were investigated using proton magnetic resonance spectroscopy ((1)H MRS). Single-voxel spectroscopy was carried out in right and left frontal lobe white matter, left parietal white matter and left occipital gray matter. Choline (Cho)/creatine (Cr) value was found to be increased in the left occipital gray matter of the subjects affected with Type 2 DM and both Type 2 DM and hypothyroidism as compared to controls. No significant change in the Cho/Cr value in the occipital gray matter was observed in hypothyroid subjects as compared to controls. However, they showed an increased level of Cho/Cr in the frontal white matter. High Cho is associated with altered membrane phospholipid metabolism. The high Cho in frontal white matter in hypothyroids and occipital gray matter in diabetic patients suggests that, though both the diseases are endocrine disorders, they differ from each other in terms of regional brain metabolite changes.     

Green approach for the synthesis of 3‐methyl‐1‐phenyl‐4‐((2‐phenyl‐1H‐indol 3‐yl)methylene)‐1H‐pyrazole‐5(4H)‐ones and their DNA Cleavage,antioxidant, and antimicrobial activities

3‐Methyl‐1‐phenyl‐4‐((2‐phenyl‐1H‐indol‐3‐yl)methylene)‐1H‐pyrazol‐5(4H)‐ones (5a‐i) was prepared by the condensation reaction of different 3‐formyl‐2‐phenylindole derivatives (2a‐i) and 3‐methyl‐1‐phenyl‐2‐pyrazoline‐5‐one in quantitative yield by applying various green synthetic methods as grinding, microwave irradiation using different catalysts under solvent‐free mild reaction conditions with high product yields. The structures of the synthesized compounds were characterized on the basis of elemental analysis, infrared, ¹HNMR, ¹³C NMR, and mass spectral data. The synthesized compounds were screened for free radical scavenging, antimicrobial, and DNA cleavage activities. Most of the tested compounds belonging to the 3‐methyl‐1‐phenyl‐4‐((2‐phenyl‐1H‐indol‐3‐yl)methylene)‐1H‐pyrazol‐5(4H)‐ones series exhibited promising activities.     

Calix[4]pyrrole virtuous sensor: a selective and sensitive recognition for Pb(II) ions by spectroscopic and computational study

A novel supramolecular sensor derived from calix[4]pyrrole system i.e. calix[4]pyrrole bearing aminoanthraquinone derivative (CAAQ) have been designed and synthesized. The complexation behavior of metal cations [Ag(I), Ba(II), Ca(II), Ni(II), Co(II), Fe(III), Hg(II), Cu(II), Cr(II), Pb(II), Zn(II), (1 × 10^?4 M)] with CAAQ (1 × 10^?6 M) was studied by spectrophotometry and spectrofluorometry. Metal ion like Pb(II) produces red shift in absorption spectra and quenching in emission spectra likelihood of strong complexation of Pb(II) ions with CAAQ. Fluorescence cell imaging also supports the complexation of Pb(II) ions with CAAQ. The binding constants, quantum yield, stoichiometry of complex, mechanism of quenching by Stern–Volmer equation and Density functional theory calculation have been determined.     

Plasma analysis of celiprolol by HPTLC: a useful technique for pharmacokinetic studies

A rapid and sensitive high performance, thin-layer chromatographic (HPTLC) method has been developed for the measurement of celiprolol in human plasma and its use in pharmacokinetic studies has been evaluated. Detection and quantitation were performed without using an internal standard. A simple extraction procedure was followed for extracting celiprolol from plasma and a known amount of the extract was spotted on precoated silica gel 60 F254 plates using a Camag Linomat IV autosampler. Celiprolol was quantitated using a Camag TLC Scanner 3. The average recovery of authentic analytes (20 to 200 ng/mL) added to plasma was 72.06 +/- 2.8% and the lowest amount of celiprolol that could be detected was 10 ng/mL. The method provides a direct estimate of the amount of celiprolol present in plasma. Pharmacokinetic parameters of 2 marketed preparations have also been determined after oral administration to 12 healthy human volunteers.