Templated synthesis and assembly with sustainable cellulose nanomaterial for functional nanostructure

Cellulose - Templated synthesis and assembly for nanostructured materials with tailored properties have received considerable attention. The powerful templates with predefined structures can guide...     

Decolorization of textile dye effluent by genetically improved bacterial strains

Synthetic dyes are released into the environment from textile industrial effluents. The discharge of this colored wastewater into rivers and lakes leads to a reduction in sunlight penetration in natural water bodies, which, in turn, decreases both photosynthetic activity and dissolved oxygen concentration and is toxic to living beings. Bacterial isolates are optimized for growth and biomass production before using them for decolorizing dye effluent. The bacterial isolates Bacillus sp. 1 and Bacillus sp. 2 were employed at different percentages by volume with standard nutrient concentration. Of these bacterial isolates Bacillus sp. 2 recorded maximum color reduction. The pH and electrical conductivity (EC) were reduced in the decolorized effluent, and a reduction in biologic oxygen demand, chemical oxygen demand, total suspended solids, and total dissolved solids (TDS) were also observed.     

Synthesis and characterization of 1,3-bis(2-hydroxyethoxy) benzene based saturated and unsaturated polyesters

Polyesterification of adipic acid and maleic anhydride with 1,3-bis(2-hydroxyethoxy)benzene (HER) in the presence of toluene-4-sulphonic acid was carried out using melt condensation technique. The structural characterization of the synthesized polyesters had been carried out using Fourier transform infrared (FTIR) and proton nuclear magnetic resonance (¹H NMR) spectroscopic methods. The thermal properties of the polyesters were studied using differential thermal analysis (DTA) and thermogravimetric analysis (TGA). The activation energies for the thermal degradation of the polyesters were calculated by the method of Dharwadkar and Kharkhanavala and discussed. The char residue value at 600 °C indicated maleic anhydride based polyester is thermally more stable compared to the adipic acid based polyester. The mechanism of degradation of these polyesters is discussed.     

Isolation of eupatorin (3′,5-dihydroxy-4′,6,7-trimethoxyflavone) from Albizia odoratissima and its application for l-tryptophan sensing

Research on Chemical Intermediates - A simple fluorescence sensor for selective detection of L-Tryptophan (Trp) was developed by isolation of naturally occurring flavone Eupatorin...     

Synthesis and photophysical,antibacterial studies of some novel molecular tweezers

Zeroth and first generation dendritic wedges with thiophene amide as surface group and 1, 2, 3-triazole as bridging unit which can function as molecular tweezers are synthesised by both convergent and divergent approaches. All the synthesised dendritic wedges displayed the absorbance band between 256 and 294 nm and fluorescence maximum between 357 and 528 nm supporting their self complementary property. Dendritic wedge 5 showed better antibacterial activity than other dendritic wedges in the assay against the human pathogens viz Staphylococcus aureus, Escherichia coli, Bacillus cereus and Klebsiella pneumonia and the dentritic wedge 5 was also effective in the computational molecular docking studies.     

Green Chemical Synthesis of N-Cholyl-L-Cysteine Encapsulated Gold Nanoclusters for Fluorometric Detection of Mercury Ions

Herein we report a simple, single-step, cost-effective, environmentally friendly, and biocompatible approach using sodium salt of N-cholyl-L-cysteine (NaCysC) capped gold nanoclusters (AuNCs) with green emission properties at above the CMC in aqueous medium under UV-light irradiation. The primary and secondary CMC of NaCysC was found to be 4.6 and 10.7 mM respectively using pyrene as fluorescent probe. The synthesized AuNCs exhibit strong emission maxima at 520 nm upon excitation at 375 nm with a large Stokes shift of 145 nm. The surface functionality and morphology of NCs are studied by fourier transform infrared spectroscopy, dymanic light scattering studies and transmission electron microscopy. The formation of AuNCs was completed within 5 h and exhibit high stability for more than 6 months. The NaCysC templated AuNCs selectively quenches the Hg²⁺ ions with higher sensitivity in aqueous solution over the other metal ions. The fluorescence analysis of Hg²⁺ showed a wide linear range from 15 to 120 µM and a detection limit was found to be 15 nM.

     

Effect of structure on the thermal degradation and flame retardancy of hexolic anhydride based polyesters

Based on the anhydrides like hexolic (5,6,7,8,10,10-hexachloro -3a,4,4a,5,8,8a,9,9a-octahydro-5,8-methanonaphtho-[2,3-c]-furan-1,3-dione), maleic and phthalic and diols like 1,4-butanediol, cis-2-butene-1,4-diol and 2,3-dichloro-2-butene-1,4-diol, a family of polyesters has been synthesized using azeotropic condensation technique. The structural characterizations of the polyesters have been carried out using infra-red, 1^H - and ¹³C- nuclear magnetic resonance spectroscopic methods. The thermal properties of the polyesters have been studied using thermogravimetric technique. The off-line pyrolysis of these materials was done. The qualitative and semi-quantitative analyses of the volatiles as well as the heavy mass fractions of the degradation products were carried out using a gas chromatograph coupled to a mass selective detector (GC-MSD). Thermogravimetric data indicate that the thermal stability and the char residue of the polyester resins decrease in the order 1,4-butanediol based>cis-2-butene-1,4-diol based>2,3-dichloro-2-butene-1,4-diol based polyesters. The GC-MSD data indicate that the amount of flame cooling agents (hexa-, isomeric penta-, tetra- and isomeric tri-chlorocyclopentadienes) produced during the pyrolysis of the polyesters increases in the order 2,3-dichloro-2-butene-1,4-diol based<cis-2-butene-1,4-diol based<1,4-butanediol based polyesters. The trends observed in these two parameters which are contributing factors to the flame retardancy of the polyester materials were suitably explained on the basis of the effect of the structural changes in the diol part of the polyesters on the primary degradation mechanism, the β-chain scission process.     

Synthesis,characterization and catalytic studies of ruthenium(II) Schiff base complexes

Complexes of the type [Ru(CO)(EPh₃)(B)(L)] (E = P or As; B = PPh₃, AsPh₃, py or pip; L = dianion of the Schiff bases derived from the condensation of salicyloyl hydrazide with acetone, ethyl methyl ketone and salicylaldehyde have been synthesised by the reaction of equimolar amounts of [RuHCl(CO)(EPh₃)₂(B)] and Schiff bases in benzene. The resulting complexes have been characterized by analytical and spectral (i.r., electronic, n.m.r.) data. The arrangements of Ph₃P groups around the Ru metal was determined from ³¹P-n.m.r. spectra. An octahedral structure has been assigned to all the new complexes. All the complexes exhibit catalytic activity for the oxidation of benzyl alcohol and cyclohexanol in the presence of N-methylmorpholine-N-oxide as co-oxidant.     

Thermal degradation studies on PMMA–HET acid based oligoesters blends

Imparting thermal stability to polymethyl methacrylate (PMMA) without affecting its optical clarity is attempted by incorporating HET acid based oligoesters. Pure PMMA and PMMA containing five and 20 wt% of four different oligoesters are separately prepared using bulk polymerization. The thermal properties of the materials studied using DSC, TG, TG–FTIR and Pyr–GC–MS are presented. The main volatile degradation products identified are CO, HCl, CO₂, H₂O, hexachlorocyclopentadiene, hexachloroendomethylene tetrahydrophthalic acid/anhydride and methyl methacrylate. A detailed mechanism for the influence of the degradation products of HET acid based oligoesters on the thermal degradation of PMMA is also presented.     

Chlorinated thermal stabilizer for optically clear PMMA

Optically clear poly(methyl methacrylate) (PMMA) blends with HET‐EG oligoester (synthesized by condensation of chlorendic acid with ethylene glycol) at six different compositions were prepared by bulk polymerization. The effect of HET‐EG in the PMMA matrix on the optical clarity of PMMA blend was measured using ultraviolet‐visible spectroscopic study. The thermal stability of PMMA blends was investigated using differential scanning calorimetric (DSC) and thermogravimetric (TG) analyses. The parameters to deduce the thermal stability of pure PMMA and PMMA blends were calculated from DSC and TG results. The thermal stability of PMMA was found to increase effectively by loading 5% of HET‐EG oligoester without marring optical clarity. The probable physical and chemical actions of HET‐EG oligoester on the thermal stability of PMMA are discussed. Copyright © 2011 John Wiley & Sons, Ltd.