Polyaniline nanostructures expedient as working electrode materials in supercapacitors

Granular type polyaniline (PANi), PANi nanofibers (NFs), and PANi nanotubes (NTs) expedient as working electrode materials for supercapacitors are synthesized. The synthesis procedure used in this work facilitates not only the synthesis of solid powders of the PANi nanostructures, but also thin films constituted by the same PANi nanostructures in the same experiment. PANi NFs are found to exhibit faster electrode kinetics and better capacitance when compared to PANi NTs and granular PANi. Specific capacitance and energy storage per unit mass of PANi NFs are 239.47 Fg^?1 (at 0.5 Ag^?1) and 43.2 Wh?kg^?1, respectively. Electrical conductivity of PANi NFs is also better when compared to the other two nanostructures. Properties of the three PANi nanostructures are explicated in correlation with crystallinity, intrinsic oxidation state, doping degree, BET surface area, and ordered mesoporosity pertaining to the nanostructures.     

Label-free flow cytometry using multiplex coherent anti-Stokes Raman scattering (MCARS) for the analysis of biological specimens

We present the first demonstration, to our knowledge, of a label-free flow cytometer for the analysis of biological specimens using multiplex coherent anti-Stokes Raman scattering (MCARS) and elastic scatter measurements. The MCARS system probes the Raman vibrational energy levels and the elastic scatter provides morphological information. We demonstrate these capabilities by probing a culture of Saccharomyces cerevisiae at 100 spectra/s and constructing a background-free Raman reconstruction using a Kramers-Kronig relation. A theoretical analysis shows that this system could operate at speeds of 10 kHz with appropriate hardware; thus facilitating integration into commercial flow cytometers or use as a high-speed, stand-alone device.     

Yb(OTf)3 catalyzed new cascade reaction: a facile assembly of fused quinazolinones

A one-pot Yb(III)-mediated cascade reaction has been developed leading to small molecules based on a novel structural motif, i.e. quinazolin-4-one moiety fused with an isoquinoline ring, for potential inhibition of TNF-α.     

Synthesis of Novel Isoxazolyl 1,6-Dithia-4,9-diazaspiro[4,4]nonane-3,8-diones and 1-Oxa-6-thia-2,4,9-triazaspiro[4,4]non-2-ene-8-ones

The key intermediates, 3-(5-methyl-3-isoxazolyl)-2-arylimino-1,3-thiazolan-4-ones (3), were obtained from 3-amino-5-methylisoxazole (1) by reaction with chloroacetyl chloride followed by treatment with aryl isothiocyanates. Cyclocondensation of 3 with mercapto acetic acid furnished novel isoxazolyl 1,6-dithia-4,9-diazaspiro[4,4]nonane-3,8-diones (4). Cycloaddition of 3 with benzonitrile oxides afforded novel isoxazolyl 1-oxa-6-thia-2,4,9-triazaspiro[4,4]non-2-ene-8-ones (5).     

Synthesis,antibacterial and anti-inflammatory activity of bis(indolyl)methanes

A series of bioactive bis(indolyl)methanes are synthesized by one-pot green reaction of indole with various substituted aldehydes by microwave irradiation under solvent free conditions. The antibacterial activity against Staphylococcus aureus and anti-inflammatory activity of the synthesized bis(indolyl)-methanes are evaluated in vitro and compared to standard drugs tetracycline and diclofenac, respectively. The majority of the compounds showed good antibacterial and anti-inflammatory activity. Interestingly, compounds 3j, 3i, 3k and 3g exhibited much higher anti-inflammatory activity than the standard diclofenac drug and thus qualify for clinical trials to be used as an anti-inflammatory compound.     

A convenient one-pot synthesis of thiazol-2-imines: application in the construction of pifithrin analogues

For the first time a reaction intermediate has been isolated giving further insight into the mechanism of thiazol-2-imine formation. The first step of the reaction requires a basic medium, while the second step is an acid mediated E1 elimination reaction. An efficient one-pot synthesis of substituted thiazol-2-imines have been achieved by the condensation of carbonyl compounds with thioureas and 1,3-disubstituted thioureas using 1,1′-(ethane-1,2-diyl)dipyridinium bistribromide (EDPBT). Unsymmetrical 1,3-disubstituted thioureas give regioselective products with symmetrical ketones, which are mainly governed by the pK_as of NH protons of thiourea, whereas symmetrical 1,3-disubstituted thioureas give regioselective products with symmetrical carbonyl compounds owing to the regioselective bromination of ketones. The methodology is extended to access novel neurodegenerative drug candidate pifithrin-α analogues in good yields in shorter reaction time. This method is simple, versatile and is applicable for different 1,3-disubstituted thioureas as well as a range of carbonyl compounds.     

Biosorption of nickel from aqueous solutions by Acacia leucocephala bark: Kinetics and equilibrium studies

The biosorption of nickel(II) ions from aqueous solution by Acacia leucocephala bark was studied in a batch adsorption system as a function of pH, initial metal ion concentration, adsorbent dosage, contact time and temperature. The maximum Ni(II) adsorption was obtained at pH 5. Further, the biosorbents were characterized by Fourier Transformer Infrared Spectroscopy (FTIR). The experimental data were analysed using three sorption kinetic models viz., the pseudo-first- and second-order equations and the intraparticle diffusion model. Results show that the pseudo-second-order equation provides the best correlation for the biosorption process. The equilibrium nature of Ni(II) adsorption at different temperatures of 30, 40 and 50 °C have been described by the Langmuir and Freundlich isotherm models. The equilibrium data fit well Langmuir isotherm. The monolayer adsorption capacity of A. leucocephala bark as obtained from Langmuir isotherm at 30 °C was found to be 294.1 mg/g. The Chi-square (χ²) and Sum of the square errors (SSE) tests were also carried out to find the best fit adsorption isotherm and kinetic model. Isotherms have been used to determine thermodynamic parameters of the process, viz., free energy change (ΔG°), enthalpy change (ΔH°), and entropy change (ΔS°) were calculated indicating that this system was a spontaneous and endothermic process. Present investigation emphasized that A. leucocephala bark may be utilized as a low cost adsorbent for nickel removal.     

Efforts towards the synthesis of microsporin B: ready access to both the enantiomers of the key amino acid fragment

Both the isomers methyl-(2S,8R)-2-((tert-butoxycarbonyl)amino)-8-hydroxydecanoate and methyl-(2S,8S)-2-((tert-butoxycarbonyl)amino)-8-hydroxydecanoate of an unusual amino acid residue and the key fragment of microsporin B are prepared. The key steps include cross metathesis and enzymatic kinetic resolution. In addition, a linear tetrapeptide with desired components towards total synthesis is also reported.