An insight into the potent antioxidant activity of a dithiocarbohydrazone appended cis-dioxidomolybdenum (VI) complexes

In search of antioxidants with enriched potency, the present study focus on the design and synthesis of a dithiocarbohydrazone, H₃TCL derived from thiocarbohydrazide and 3-ethoxysalicylaldehyde and its coordination complexes with molybdenum, viz, [MoO₂(HTCL)D] ( 1 – 2 ) (where D = methanol ( 1 ), DMSO ( 2 )) and [MoO₂(HTCL)D]·DMF (where D = H₂O ( 3 )). The synthesized compounds were characterised by elemental analysis, spectroscopic techniques (FT-IR, UV–vis and ¹H-NMR), conductivity measurements and cyclic voltammetry. Moreover the solid state structures of all the three complexes were established by single crystal X-ray diffraction analysis as mononuclear neutral species in which the molybdenum centre assumes a distorted octahedral geometry. The dithiocarbohydrazone binds to the molybdenum centre through its phenolate oxygen, O(1), azomethine nitrogen, N(1) and thioenolate sulfur, S(1) in a dianionic tridentate mode. The assessment of intermolecular contacts in the crystal arrangement was quantified using Hirshfeld surface analysis. Further the antioxidant potential of the dithiocarbohydrazone, H₃TCL and its molybdenum complexes 1 – 3 were evaluated using 1,1-diphenyl-2-picrylhydrazyl(DPPH), 2,2′-azinobis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS) and total antioxidant assays. The antioxidant activities were then compared with standard antioxidant, L-ascorbic acid. The antioxidant potential of the synthesized compounds were then validated by molecular docking studies. Molecular modelling study was achieved to evaluate the recognition of target compound at the binding pocket of the human antioxidant enzyme, 3MNG. The docking results showed that the complexes selectively bond to the vital amino acids present in the binding pocket of the target enzyme, 3MNG.     

High-performance thin-layer chromatography method for the quantification of quetiapine fumarate and its related genotoxic impurities using green solvents

A novel high-performance thin-layer chromatographic (HPTLC) analytical method has been developed and optimized for the quantification of quetiapine fumarate (QF) and its two genotoxic impurities in drug substance and drug product. The desired separation was achieved on 60F₂₅₄ pre-coated HPTLC plates using combination of green solvents, ethyl acetate‒ethanol‒n-heptane (5:1:4, V/V) as developing solvents. The detection wavelength used for quantification was 229 nm. QF and its two related genotoxic impurities, namely, 2-chloroaniline and 2-aminodiphenylsulfide, were well resolved from one another with retention factor values of 0.13 ± 0.02, 0.57 ± 0.02 and 0.76 ± 0.02, respectively. The optimized method was validated according to the guidelines laid down by the International Council for Harmonisation. The linearity was determined in the range of 100–600 ng/spot for QF and 10‒60 ng/spot for its two related genotoxic impurities; R² ≥ 0.993. The method exhibited precision along with good accuracy, where 0.51, 0.86 and 1.86. The percentage recoveries obtained for 2-chloroaniline and 2-aminodiphenylsulfide were 99.04‒101.04%. The developed method can be successfully used for the analysis of drug samples.

     

Chloride‐Anion‐Templated Synthesis of a Strapped‐Porphyrin‐Containing Catenane Host System

The synthesis, structure and anion‐recognition properties of a new strapped‐porphyrin‐containing [2]catenane anion host system are described. The assembly of the catenane is directed by discrete chloride anion templation acting in synergy with secondary aromatic donor–acceptor and coordinative pyridine–zinc interactions. The [2]catenane incorporates a three‐dimensional, hydrogen‐bond‐donating anion‐binding pocket; solid‐state structural analysis of the catenane?chloride complex reveals that the chloride anion is encapsulated within the catenane’s interlocked binding cavity through six convergent CH????Cl and NH???Cl hydrogen‐bonding interactions and solution‐phase ¹H NMR titration experiments demonstrate that this complementary hydrogen‐bonding arrangement facilitates the selective recognition of chloride over larger halide anions in DMSO solution.     

Twin liquid crystals and segmented thermotropic polyesters containing azobenzene—effect of spacer length on LC properties

We report systematic studies on a homologous series of twin liquid crystalline (LC) molecules based on phenyl and naphthyl azobenzene ( PnP and NpnNp ) as well as segmented copolyesters based on them. The twin series had the structure azobenzene–oligooxyethylene–azobenzene, where the ethyleneoxy length was varied from 2 to 6 units. The LC properties of the twin series depended on the chemical structure of the azochromophore and also the length of the central oligooxyethylene segment. The PnP series exhibited smectic LC properties for n > three oligooxyethylene units. Conversely, NpnNp series exhibited spherulitic phases only for the shortest member – Np2Np . One non‐LC short spacer twin ( P2P ) and one LC long spacer twin ( P6P ) were incorporated as part of a main chain polyester composed of fully aliphatic segments of sebacate and di or tetraethylene glycol (DEG/TEG) units by melt polycondensation. Non‐LC P2P formed LC polymers even at low (5 mol %) incorporation in DEG‐based copolymers, whereas the LC‐ P6P could do so only at 30 mol % incorporation. The LC properties of the twin molecules as well as copolymers were studied using differential scanning calorimetry, polarized light microscopy (PLM) along with variable temperature wide angle X‐ray diffraction. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Regioselective Synthesis of Diltiazem Analogue Pyrazolo[4,3-c][1,5]benzothiazepines and Antifungal Activity

A dry media procedure has been developed for the synthesis of a series of new class of pyrazolo [4,3-c][1,5]benzothiazepines 6 under microwave irradiation using montmorillonite K10 as solid support. The catalyst can be recovered and reused. Thus, the procedure provides a simple and green synthetic methodology under environmentally friendly conditions. Antifungal screening of synthesized compounds has shown promising activity.

Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file.     

IR, Raman and SERS spectra of 2-phenoxymethylbenzothiazole

The FT-IR and FT-Raman spectra of 2-phenoxymethylbenzothiazole were recorded and analyzed. The surface enhanced Raman scattering (SERS) spectrum was recorded in a silver colloid. The vibrational wavenumbers of the compound have been computed using the Hartree–Fock/6-31G* basis and compared with the experimental values. The appearance of the Ag–O stretching mode at 237 cm⁻¹ in the SERS spectrum along with theoretically calculated atomic charge density, leads us to suggest that the molecule is adsorbed through the oxygen atom with the molecular plane tilted on the colloidal silver surface. The direction of charge transfer contribution to SERS has been discussed from the frontier orbital theory.     

Polymer blend nanocomposites: effect of mercapto silane modified kaolin clay on the thermal properties of Polypropylene/Polystyrene blend

Nanocomposites based on polypropylene/polystyrene blends were prepared by melt mixing in a Thermo Haake Rheochord mixer. The effect of mercapto silane modified kaolin clay on the properties of nanocomposites has been studied. The characterization of polypropylene/polystyrene/clay nanocomposites was made by dynamic mechanical analysis, scanning electron microscope, and transmission electron microscopic, and the thermal stability was determined by using Thermogravimetric analysis. The activation energy of degradation was determined using three mathematical models, namely Horowitz–Metzger, Coats–Redfern and Broido's methods, and the results were compared. TGA results show an improved thermal stability for nanocomposite than the pure blend. The improvement in thermal stability of nanocomposites was confirmed by increasing the activation energy. Transmission electron microscopic observations showed that nanoclay layers were intercalated on the polymer matrix and were located at the interface between the two polymers Copyright © 2014 John Wiley & Sons, Ltd.