Unusual stabilization of water-soluble colloidal MnO2 during the oxidation of paracetamol by

The kinetics of the formation and decomposition of water-soluble colloidal MnO₂ in the paracetamol– redox system have been investigated spectrophotometrically in aqueous-neutral media at 30 °C. Upon mixing aqueous solutions of permanganate and paracetamol, a readily distinguishable brown color appears and then disappears slowly. Experiments have been done to confirm the nature of intermediate (Mn(IV)) formed during the reduction of permanganate by paracetamol. The stoichiometry was found to be 1:1. Formation and decomposition of water-soluble colloidal MnO₂ depend upon the experimental conditions, i.e., [paracetamol] and [H⁺]. The effect of total [paracetamol], and [H⁺] on the rate of the reaction was determined. On the basis of various observations, two mechanisms are proposed: one for MnO₂ formation and the other for decomposition.     

Effects of anionic and cationic micelles on the oxidation of d-dextrose by diperiodatoargentate(III)

The oxidative behavior of d-dextrose toward diperiodatoargentate(III) (DPA) has been studied in the absence and presence of anionic and cationic micelles of sodium dodecyl sulfate (SDS) and cetyltrimethylammonium bromide (CTAB), respectively. The kinetics is based on the reduction of silver(III) to silver(I) by d-dextrose under pseudo-first-order conditions. The monoperiodatoargentate(III) ions act as active oxidants in comparison to that of DPA. The reactions are first- and fractional-order dependence with respect to [DPA] and [d-dextrose], respectively. The reaction rates decrease with [H⁺] and [periodate]. The premicellar environment of SDS and CTAB strongly inhibits the reaction rate. Inhibition is due to favorable thermodynamic/electrostatic binding between the Ag(III) complex and CTAB monomer aggregates. A suitable mechanism involving a one-electron transfer (rate-determining step) from d-dextrose to the silver(III) species has been proposed. Activation parameters have been evaluated and discussed.     

Synthesis and characterisation of four- and six-membered P-Se heterocycles

The preparation, spectroscopic characterisation and crystal structures of [FcP(mu-Se)Se]2, [FcP(mu-Se2)Se]2 and [PhP(mu-Se2)Se]2 are reported. Crystallographic data reveal planar four-membered PSePSe and skewed six-membered P2Se4 rings, respectively, in all cases with trans arrangement of organic substituents and exo selenium atoms. Whilst stable at room temperature in solid state, NMR data suggest the six-membered rings of both the ferrocenyl and phenyl compounds decompose in the solution with loss of red selenium, forming PSe2PSe five-membered rings.     

Semiquantitative determination of alkaloids by circular thin-layer chromatography

Summary A semiquantitative method for the determination of 13 alkaloids (nicotine, quinine, strychnine, brucine, ephedrine, pilocarpine, narcotine, cinchonine, ajmaline, atropine, cocaine, papaverine and morphine) from a single drop of solution by making circular spots on chromatoplate with the circular thin-layer Chromatographic apparatus and their comparison with sensitivity standard has been developed. The accuracy is ±5% and the procedure is rapid, simple and economical.

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Zusammenfassung Ein halbquantitatives Verfahren zur Bestimmung von 13 Alkaloiden (Nikotin, Chinin, Strychnin, Brucin, Ephedrin, Pilokarpin, Narkotin, Cinchonin, Aimalin, Atropin, Kokain, Papaverin und Morphin) in 1 Tropfen Lösung durch zirkuläre Dünnschichtchromatographie und Vergleich mit Standard-Ringen wurde ausgearbeitet. Die Genauigkeit des Verfahrens beträgt ±5%.

     

Structure of lithium (picrate) (2,2′-bipyridyl)

The title compound C₁₆H₁₀N₅O₇Li is triclinic, witha=14.51(1),b=6.90(2),c=9.10(1) Å,=101.5(1),=67.1(2), =105.6°(1),Z=2 and space groupP¯1. Data were measured by photographic methods. The structure was solved by direct methods, and refined by full matrix least-squares. The refinement, based on 1337 reflections, gave the rather highR value of 0.11 because of poor quality data. The complex is dimeric. The coordination around the cation is distorted square-pyramidal. Two coordination sites are occupied by the nitrogen atoms of the bipyridyl ligand, two by the phenolic oxygen and oxygen ofo-nitro group, and the fifth coordination site is occupied by the phenolic oxygen belonging to the symmetry-related molecule (1–x,–y,1–z). Both oxygens act as bridges to form the dimer. The bridging is unsymmetrical, with Li-O (phenolic)=1.84(2) Å and Li¹-O (phenolic)=2.16(2) Å (whereI=1–x,–y, 1–Z).     

New anti‐bacterial polychelates: synthesis,characterization, and anti‐bacterial activities of thiosemicarbazide–formaldehyde resin and its polymer–metal complexes

New polymeric ligand (resin) was prepared by the condensation of thiosemicarbazides with formaldehyde in the presence of acidic medium. Thisemicarbazide–formaldehyde polymer–metal complexes were prepared with Mn(II), Co(II), Ni(II), Cu(II) and Zn(II) in 1:2 metal:ligand molar ratio. The polymeric ligand and its polymer–metal complexes were characterized by elemental analysis, thermogravimetric analysis (TGA), FTIR, ¹³C NMR and ¹H NMR. The geometry of central metal ions was conformed by electronic (UV–vis) and EPR spectra. The antibacterial activities of all the synthesized polymers were investigated against Bacillus subtilis and Staphylococcus aureus (Gram‐positive) and Escherichia coli and Salmonella typhi (Gram‐negative). These compounds showed excellent activities against these bacteria using the shaking flask method. Copyright © 2008 John Wiley & Sons, Ltd.     

In vitro antibacterial and antifungal assay of poly‐(ethylene oxamide‐N,N′‐diacetate) and its polymer–metal complexes

A new polyester, poly‐(ethylene oxamide‐N,N′‐diacetate) (PEODA), containing glycine moiety was synthesized by the reaction of oxamide‐N,N′‐diacetic acid and ethylene glycol and its polymer–metal complexes were synthesized with transition metal ions. The monomer oxamide‐N,N′‐diacetic acid was prepared by the reaction of glycine and diethyl oxalate. The polymer and its metal complexes were characterized by elemental analysis and other spectroscopic techniques. The in vitro antibacterial activities of all the synthesized polymers were investigated against some bacteria and fungi. The analytical data revealed that the coordination polymers of Mn(II), Co(II) and Ni(II) are coordinated with two water molecules, which are further supported by FTIR spectra and TGA data. The polymer–metal complexes showed excellent antibacterial activities against both types of microorganisms; the polymeric ligand was also found to be effective but less so than the polymer–metal complexes. On the basis of the antimicrobial behavior, these polymers may be used as antifungal and antifouling coating materials in fields like life‐saving medical devices and the bottoms of ships. Copyright © 2007 John Wiley & Sons, Ltd.     

Adsorption modeling and mechanistic insight of hazardous chromium on para toluene sulfonic acid immobilized-polyaniline@CNTs nanocomposites

The development of highly efficient adsorbents materials for the purification of wastewater has caught a considerable deal of attention these days. Conducting polymers functionalized adsorbents has become a favorable route for enhancing their adsorption capability due to their ease of synthesis at laboratory scale. In this study, functionalized multiwalled carbon nanotube (CNT)-polyaniline (Pani) composites were fabricated using an oxidation polymerization methodology and later doped with para toluene sulfonic acid (pTSA). The CNTs provided an adequate substrate for the adhesion of Pani as well as a large surface area due to its nano size, and pTSA provided additional functionality for the adsorption of differently charged moieties through strong or weak interactions. The as-synthesized pTSA-Pani@CNT nanocomposite was analyzed by the scanning electron microscopy, transmission electron microscopy for the morphological studies and the structural analysis were done by the X-ray diffraction, and X-ray photoelectron spectroscopy (XPS). The characterization results confirmed that the Pani was adhered to the CNTs as well as its successful functionalization with pTSA. The pTSA-Pani@CNT composite was then applied to the adsorptive removal of hexavalent chromium (Cr(VI)) and the composite showed higher adsorption for Cr(VI) than pTSA-CNT and pTSA-Pani, and the maximum removal level was detected at acidic pH. The analyses of the equilibrium isotherms and adsorption kinetics were performed to elucidate the adsorption mechanism. The XPS analysis indicated that Cr(VI) was strongly bounded to the adsorbent and it further indicated that the amine, imine, and hydroxyl functional groups were involved in the adsorption process. This study presents a new insight for the fabrication of highly functional polymer-carbonaceous nanocomposites for the scavenging of heavy metals from water bodies.     

Chemical and pharmacological comparison of modern and traditional dosage forms of Joshanda

Recently, a traditional remedy (Joshanda) has been replaced largely by modern ready-to-use dosage forms, which have not been compared to the original remedy. Therefore, the present study aimed to compare a number of modern dosage forms with traditional remedy. Seven brands, 3 batches each, were compared with a Lab-made formulation with reference to analytical (proximate analyses, spectroscopic and chromatographic metabolomes) and pharmacological profiles (anti-inflammatory and antibacterial activities). Chemical and pharmacological differences were found between Lab-made Joshanda and modern dosage forms. Such variations were also found within the brands and batches of modern formulations (p < 0.05). The Lab-made Joshanda showed significantly higher pharmacological activities as compared to modern brands (p ). The results of the present study indicate that modern dosage forms are unstandardised and less effective than the traditional remedy. Characteristic profiles obtained from Lab-made Joshanda may be used as reference to produce comparable dosage forms.     

Estimation of the proton affinity values of fifteen matrix-assisted laser desorption/ionization matrices under electrospray ionization conditions using the kinetic method

The kinetic method, which is known to be simple, fast and precise, is used for the measurement of proton affinity values of fifteen selected matrix-assisted laser desorption/ionization matrices under electrospray ionization conditions. The stabilization of [M - H](-)/[M + Matrix - H](-) ions for beta-cyclodextrin in negative ion mode has been rationalized based on the proton affinity values of the matrices.