C-H Amidation and Amination of Arenes and Heteroarenes with Amide and Amine using Cu-MnO as a Reusable Catalyst under Mild Conditions.

An atom-economical and efficient route for the direct amidation and amination of aryl C-H bonds using our synthesized recyclable heterogeneous Cu-MnO catalyst is reported here. The direct C-H amidation was carried out using a simple amide without any preactivated coupling partner, and simple air was used as the sole oxidant. The reaction proceeds very smoothly with a broad range of substrates containing numerous functional groups in very good to excellent yields.

N-Doped Yellow TiO Hollow Sphere-Mediated Visible-Light-Driven Efficient Esterification of Alcohol and N-Hydroxyimides to Active Esters.

Herein we report a simple synthetic protocol for N-doped yellow TiO (N-TiO ) hollow spheres as an efficient visible-light-active photocatalyst using aqueous titanium peroxocarbonate complex (TPCC) solution as precursor and NH OH. In the developed strategy, the ammonium ion of TPCC and NH OH acts as nitrogen source and structure-directing agent. The synthesized N-TiO hollow spheres are capable of promoting the synthesis of active esters of N-hydroxyimide and alcohol through simultaneous selective oxidation of alcohol to aldehyde followed by cross-dehydrogenative coupling (CDC) under ambient conditions upon irradiation of visible light.

Novel nanocomposite derived from ZnO/CdS QDs embedded crosslinked chitosan: An efficient photocatalyst and effective antibacterial agent.

A novel nanocomposite (cl-Ch-pMAc@ZnO/CdSQDs) has been developed under microwave irradiation via fabrication of ZnO/CdS quantum dots on anionically functionalized chitosan [i.e. poly (methacrylic acid) crosslinked chitosan (cl-Ch-pMAc) in the presence of diethylene glycol dimethacrylate (DEGDMA) crosslinker].

Enhanced Thermocatalytic Activity of Porous Yellow ZnO Nanoflakes: Defect- and Morphology-Induced Perspectives.

Herein, we report a simple and effective strategy for the synthesis of yellow ZnO (Y-ZnO) nanostructures with abundant oxygen vacancies on a large scale, through the sulfidation of ZnO followed by calcination. The developed strategy allows retention of the overall morphology of Y-ZnO compared with pristine ZnO and the extent of oxygen vacancies can be tuned. The influence of oxygen deficiencies, the extent of defect sites, and the morphology of ZnO on its solution-phase thermocatalytic activity has been evaluated in the synthesis of 5-substituted-1H-tetrazoles with different nitriles and sodium azide.

Hydrogenation of Furfural with Nickel Nanoparticles Stabilized on Nitrogen-Rich Carbon Core-Shell and Its Transformations for the Synthesis of γ-Valerolactone in Aqueous Conditions.

In this article, we report the synthesis of nitrogen-rich carbon layer-encapsulated Ni(0) nanoparticles as a core-shell structure (Ni@N/C-g-800) for the catalytic hydrogenation of furfural to furfuryl alcohol. The nickel nanoparticles were stabilized by the nitrogen-rich graphitic framework, which formed during the agitation of nickel acetate-impregnated cucurbit[6]uril surface in a reducing atmosphere. Furthermore, the catalyst was characterized using various physicochemical methods such as powder X-ray diffraction, Raman, field emission-scanning electron microscopy, high-resolution transmission electron microscopy, X-ray photoelectron spectroscopy, Brunauer-Emmett-Teller surface area, CO-temperature-programmed desorption, inductive coupled plasma, and CHN analyses.

Visible-light-driven Efficient Photocatalytic Reduction of Organic Azides to Amines over CdS Sheet-rGO Nanocomposite.

CdS sheet-rGO nanocomposite as a heterogeneous photocatalyst enables visible-light-induced photocatalytic reduction of aromatic, heteroaromatic, aliphatic and sulfonyl azides to the corresponding amines using hydrazine hydrate as a reductant. The reaction shows excellent conversion and chemoselectivity towards the formation of the amine without self-photoactivated azo compounds. In the adopted strategy, CdS not only accelerates the formation of nitrene through photoactivation of azide but also enhances the decomposition of azide to a certain extent, which entirely suppressed formation of the azo compound.

Hydrogenated MoS QD-TiO heterojunction mediated efficient solar hydrogen production.

Herein, we report the development of a hydrogenated MoS QD-TiO (HMT) heterojunction as an efficient photocatalytic system via a one-pot hydrothermal reaction followed by hydrogenation. This synthetic strategy facilitates the formation of MoS QDs with an enhanced band gap and a proper heterojunction between them and TiO, which accelerates charge transfer process. Hydrogenation leads to oxygen vacancies in TiO, enhancing the visible light absorption capacity through narrowing its band gap, and sulfur vacancies in MoS, which enhance the active sites for hydrogen adsorption.

Visible-Light-Induced Efficient Selective Oxidation of Nonactivated Alcohols over {001}-Faceted TiO with Molecular Oxygen.

In the presence of molecular oxygen, a {001}-faceted nanocrystalline anatase TiO catalyst enabled the selective oxidation of nonactivated aliphatic alcohols to the corresponding aldehydes or ketones under visible light. The reaction shows excellent conversion and selectivity towards the formation of the carbonyl products without over-oxidation to the corresponding carboxylic acids. The exceptional reactivity of the catalyst is possibly due to the absorption of visible light originating from a stronger interaction of alcohol with the {001} facet, which facilitates the modification of the band structure of TiO , thus facilitating the photogenerated hole transfer and subsequent oxidation processes.

pH triggered superior selective adsorption and separation of both cationic and anionic dyes and photocatalytic activity on a fully exfoliated titanate layer-natural polymer based nanocomposite.

A fully exfoliated titanate layer-natural polymer amylopectin based nanocomposite, with pH responsive superior selective adsorption, separation of both cationic (MB: 599 mg g(-1) at pH 9) and anionic (MO: 558 mg g(-1) at pH 3) dyes and photodegradation properties, has been realized through simultaneous in situ layered titanate formation, exfoliation and polymerization.

Stimulus-Responsive, Biodegradable, Biocompatible, Covalently Cross-Linked Hydrogel Based on Dextrin and Poly(N-isopropylacrylamide) for in Vitro/in Vivo Controlled Drug Release.

A novel stimulus-sensitive covalently cross-linked hydrogel derived from dextrin, N-isopropylacrylamide, and N,N'-methylene bis(acrylamide) (c-Dxt/pNIPAm), has been synthesized via Michael type addition reaction for controlled drug release application. The chemical structure of c-Dxt/pNIPAm has been confirmed through Fourier transform infrared (FTIR) spectroscopy and (1)H and (13)C NMR spectral analyses. The surface morphology of the hydrogel has been studied by field emission scanning electron microscopic (FE-SEM) and environmental scanning electron microscopic (E-SEM) analyses.

Efficient photocatalytic selective nitro-reduction and C-H bond oxidation over ultrathin sheet mediated CdS flowers.

We report here a visible light driven selective nitro-reduction and oxidation of saturated sp(3) C-H bonds using ultrathin (0.8 nm) sheet mediated uniform CdS flowers as catalyst under a household 40 W CFL lamp and molecular oxygen as oxidant. The CdS flowers were synthesized using a simple surfactant assisted hydrothermal method.

Dextrin and poly(acrylic acid)-based biodegradable, non-cytotoxic, chemically cross-linked hydrogel for sustained release of ornidazole and ciprofloxacin.

Herein, novel biodegradable, stimulus-responsive, chemically cross-linked and porous hydrogel has been synthesized to evaluate its applicability as an efficient carrier for sustained release of ornidazole and ciprofloxacin. The cross-linked hydrogel (c-Dxt/pAA) has been developed from dextrin and poly(acrylic acid) using N,N'-methylene bis(acrylamide) cross-linker via Michael-type addition reaction. With the variation of reaction parameters, various c-Dxt/pAA hydrogels have been synthesized to optimize the best one.

Chitosan derivatives cross-linked with iodinated 2,5-dimethoxy-2,5-dihydrofuran for non-invasive imaging.

Radiopaque polymer derivatives were successfully prepared through surface diffusion mediated cross-linking of chitosan with iodinated 2,5-dimethoxy-2,5-dihydrofuran. The incorporation of iodine in 2,5-dimethoxy-2,5-dihydrofuran was validated by (1)H NMR and mass spectroscopy. The cross-linking of the glucosamine moieties of chitosan with the iodinated product was confirmed by (13)C NMR and energy-dispersive X-ray spectroscopy.

Fluoride free synthesis of anatase TiO2 nanocrystals with exposed active {001} facets.

A novel fluoride free protocol for highly truncated anatase TiO2 nanocrystals with exposed {001} facets by preferential adsorption of CO3(2-) ions is developed. Experimental observations were corroborated by first principle quantum chemical DFT calculations. The synthesized anatase TiO2 showed improved photocatalytic activity.

Heterogeneously porous γ-MnO₂-catalyzed direct oxidative amination of benzoxazole through C-H activation in the presence of O₂.

Oxidative amination of azoles through catalytic C-H bond activation is a very important reaction due to the presence of 2-aminoazoles in several biologically active compounds. However, most of the reported methods are performed under homogeneous reaction conditions using excess reagents and additives. Herein, we report the heterogeneous, porous γ-MnO2-catalyzed direct amination of benzoxazole with wide range of primary and secondary amines.

Enhanced removal of methylene blue and methyl violet dyes from aqueous solution using a nanocomposite of hydrolyzed polyacrylamide grafted xanthan gum and incorporated nanosilica.

The synthesis and characterization of a novel nanocomposite is reported that was developed as an efficient adsorbent for the removal of toxic methylene blue (MB) and methyl violet (MV) from aqueous solution. The nanocomposite comprises hydrolyzed polyacrylamide grafted onto xanthan gum as well as incorporated nanosilica. The synthesis exploits the saponification of the grafted polyacrylamide and the in situ formation of nanoscale SiO2 by a sol-gel reaction, in which the biopolymer matrix promotes the silica polymerization and therefore acts as a novel template for nanosilica formation.

Guar gum and guar gum-oligomeric poly(vinyl alcohol) blends as novel flocculants for kaolinated waste water.

This is probably the first report on kaolin flocculation done with aqueous guar gum (GG) at various pH. Dynamic light scattering and reduced viscosity proved the polyelectrolytic feature (zeta potential) of aqueous GG which changed on changing pH. Interestingly, the molecular size of GG did not always increased with rising zeta potential due to strong intermolecular repulsion leading to macromolecular recoiling.

Acrylic acid grafted guargum-nanosilica membranes for transdermal diclofenac delivery.

Green, hydrophobic device for controlled transdermal release of diclofenac sodium was designed from in situ nanosilica/acrylic acid grafted guargum membranes. Best grafting condition was assigned and nanocomposites were formed in situ using varying proportions of aqueous nanosilica sol. Nanocomposite/drug conjugates were formed by bringing down the medium pH from 9.

Novel biodegradable nanocomposite based on XG-g-PAM/SiO2: application of an efficient adsorbent for Pb2+ ions from aqueous solution.

This article highlights the development of a novel nanocomposite based on nanosilica filled modified natural polymer (i.e. xanthan gum grafted with polyacrylamide:XG-g-PAM) for removal of Pb(2+) ions from aqueous solution.

Onion slice shaped assembled ZnS quantum wires.

Ultra-narrow wurtzite ZnS quantum wires assembled towards an onion slice shape are synthesized in water using a simple hydrothermal procedure. Wires are formed through an oriented attachment mechanism from wurtzite ZnS spherical particles. Strong confinement effect originated from the narrow width was observed and holds promise for use in broad optoelectronic device application.

Room temperature synthesis of protonated layered titanate sheets using peroxo titanium carbonate complex solution.

We report the synthesis of peroxo titanium carbonate complex solution as a novel water-soluble precursor for the direct synthesis of layered protonated titanate at room temperature. The synthesized titanates showed excellent removal capacity for Pb(2+) and methylene blue. Based on experimental observations, a probable mechanism for the formation of protonated layered dititanate sheets is also discussed.

Synthesis, assembly, and optical properties of shape- and phase-controlled ZnSe nanostructures.

Shape-, size-, and phase-controlled ZnSe nanostructures were synthesized by thermolysis of zinc acetate and selenourea using liganding solvents of octadecylamine (ODA) and trioctylphosphineoxide (TOPO) at different molar ratios. Materials synthesized in pure ODA resulted in uniform ultranarrow nanorods and nanowires of 1.3 nm in diameter.

Microwave synthesis of highly aligned ultra narrow semiconductor rods and wires.

We report on the rapid production, characterization, and spectral properties of highly uniform, ultra narrow semiconductor (ZnS, ZnSe, CdS, CdSe) nanorods and nanowires by microwave irradiation. Quantum-confinement effects are manifested in the light absorption and the PL of the rods and wires. The uniformity of the rods and of the wires is demonstrated in their spontaneous assembly into highly ordered 2D supercrystals.