Sreekantha B. Jonnalagadda

Mineralization and toxicity reduction of textile dye neutral red in aqueous phase using BiOCl photocatalysis.

The BiOCl catalyst was prepared by hydrolysis method. The compound was extensively characterized by XRD, SEM, TEM, UV-vis measurements and BET surface area. The prepared material had average pore diameter about 6-13 nm. The BET surface area of the sample is about 40 m(2)/g. The photocatalytic degradation and toxicity reduction of textile dye neutral red (NR) was investigated in the presence of as prepared BiOCl. The analysis of (·)OH radical formation was performed by fluorescence technique. The intermediates and the final products of degradation were detected by high-performance liquid chromatography-photodiode array-electrospray ionization-mass spectrometry (HPLC-ESI-DAD-MS) technology. Decrease in chemical oxygen demand (COD) and dye absorbance of the photodegraded dye solution revealed a complete mineralization of NR into CO(2) and inorganic ions. The recycling experiments confirmed the relative stability of the catalyst. Finally, the luminescent marine bacteria Vibrio fischeri was used to assess the acute toxicity of samples prior to and after the photocatalytic treatment and it was found that toxicity was fully eliminated following photocatalytic degradation.

Heavy metal uptake by two edible Amaranthus herbs grown on soils contaminated with lead, mercury, cadmium, and nickel.

The uptake of an element by a plant is primarily dependent on the plant species, its inherent controls, and the soil quality. Amaranthus hybridus (green herbs) and Amaranthus dubius (red herbs) were chosen to investigate their response and ability to accumulate and tolerate varying levels of elements in their roots and shoots. Red herbs and green herbs were grown in soil pots contaminated with three mixtures of Cd(II), Ni(II), Pb(II), and Hg(II). Plants in the control treatment were grown in the absence of the heavy metals mixture. The distribution of Cd, Ni, Pb, and Hg in the plants (in roots, stems, and leaves) was determined in two stages. Stage 1, after 5 weeks of plant growth and stage 2, full grown after 10 weeks of growth. In the red herbs the Cd concentration in the leaves at stage 2 was 150 ppm and was present in higher concentrations than Ni, Hg, and Pb. At the highest contamination level, in the green herbs plant, Hg was present in the highest concentration in the root, i.e., 336 ppm at stage 1, while the level in the leaves was 7.12 ppm. Both the green and red herbs species showed an affinity for Ni and Cd with moderate to high levels detected in the leaves, respectively.

Effectiveness of carbon nanotube–cobalt ferrite nanocomposites for the adsorption of rhodamine B from aqueous solutions

The efficiency of adsorption of rhodamine B (RhB) from aqueous solution was investigated through a series of batch experiments by using cobalt ferrite nanoparticles (CoFe2O4), acid-functionalized multiwalled carbon nanotubes (MWCNT–COOH) and carbon nanotube–cobalt ferrite nanocomposites. The adsorption capacity was evaluated as a function of pH, contact time, adsorbent dose, dye concentration and temperature. The effect of increasing the percentage of MWCNT–COOH in the nanocomposites was also studied. The adsorption capacity was lowest in CoFe2O4 (5.165 mg g−1) and highest with MWCNT–COOH (42.68 mg g−1). For the nanocomposites, the adsorption capacity was enhanced with an increase in the amount of MWCNT–COOH. The optimum pH for adsorption was observed at 7 at which equilibrium was reached after 360 min. The kinetics of adsorption was fitted to the pseudo-first order, pseudo-second order, Elovich and intraparticle diffusion models. The results showed that the pseudo-second order model best described the data as reflected in the lowest value for the sum of squared residuals. Among the various adsorption isotherms tested, the Langmuir isotherm provided the best fit to the equilibrium data. The thermodynamic parameters, ΔH°, ΔS° and ΔG°, were obtained over a temperature range of 20–45 °C. Adsorption was spontaneous, endothermic and entropy-driven, except for one of the doped nanocomposites for which adsorption was exothermic. A good desorption of RhB from the loaded adsorbents was obtained by using either acetone or ethanol with a desorption efficiency in the range of 62–95%.

Mn doped ZrO2 as a green, efficient and reusable heterogeneous catalyst for the multicomponent synthesis of pyrano[2,3-d]-pyrimidine derivatives

A simple and an efficient method has been developed for the one-pot multicomponent synthesis of pyrano[2,3-d]-pyrimidine derivatives. This was achieved through the condensation reaction between dimethylbarbituric acid, aromatic aldehyde and malononitrile in the presence of a Mn/ZrO2 heterogeneous catalyst with ethanol/water mixture as solvent for only 1 hour. Further advantages of this synthesis methodology include excellent yields, mild reaction conditions, atom economy, environmentally friendliness, reusable catalyst and no need for chromatographic separations.

Eco-efficient ultrasonic responsive synthesis of pyrimidines/pyridines.

Using ultrasound irradiation, two simple one-pot multicomponent methods are described for syntheses of highly functionalized pyrimidine/pyridine derivatives in excellent yields in the presence of NaOH at room temperature. While one route involved aromatic aldehyde, thiourea and acetoacetanilide, the other employed aromatic aldehyde, malononitrile and benzyl mercaptane or EtOH. These approaches afford several advantages over former and contemporary reaction methodologies in terms of operational simplicity, simple work-up procedure, higher yield, short reaction time and environment friendly protocols.

Ceria–Vanadia/Silica‐Catalyzed Cascade for C−C and C−O Bond Activation: Green One‐Pot Synthesis of 2‐Amino‐3‐cyano‐4H‐pyrans

Abstract We designed a ceria–vanadia/silica (Ce–V/SiO2) heterogeneous catalyst and used it for the green and efficient synthesis of 2‐amino‐3‐cyano‐4H‐pyran derivatives. The green reaction was a multicomponent one‐pot condensation of 5,5‐dimethylcyclohexane‐1,3‐dione, aromatic aldehyde, and malononitrile in an eco‐compatible solvent (ethanol). The catalyst was synthesized and fully characterized by powder X‐ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and Brunauer–Emmett–Teller (BET) surface area analysis. The reported procedure offers a number of advantages including decreased reaction times, mild conditions, high yields, operational simplicity, and environmentally benign and simple work‐up procedures. Furthermore, the catalyst is economical, fully recyclable, and reusable for over five runs while preserving its high activity. The synthesized 2‐amino‐3‐cyano‐4H‐pyran products can later be used for pharmaceutical purposes.

Synthesis and characterization of Pd(II) dispersed over diamine functionalized graphene oxide and its scope as a catalyst for selective oxidation

A protocol for synthesis of active palladium(II) over diamine functionalized graphene oxide (Pd(II)-AAPTMS@GO) is described. The catalyst gave excellent conversion (96%) of benzyl alcohol with 99% selectivity towards benzaldehyde. The active catalytic material was fully characterized by BET surface area analysis, X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Based on the FT-IR results, the organic amine was successfully grafted over the graphene surface. The palladium distribution on the graphene oxide surface was confirmed by TEM. The catalytic activity remained unaltered in the first five cycles, but the efficiency of conversion and yield dropped to 89% in the 6th cycle.

Ultrasonic-accelerated rapid protocol for the improved synthesis of pyrazoles.

A simple, catalyst-free, green synthetic protocol is described for the one-pot synthesis of pyrazoles via multicomponent reaction of aromatic aldehydes, hydrazine monohydrate and ethyl acetoacetate and malononitrile/ammonium acetate in water under ultrasound irradiation. This protocol avoids traditional chromatography and purification steps and it affords highly selective conversion with no byproducts.

Synthesis and Biological Activity of Ethyl 2-(substituted benzylthio)-4-(3′-(ethoxycarbonyl)biphenyl-4-yl)-6-methyl-1,4-dihydropyrimidine-5-carboxylate Derivatives

In the present study, a new series of ethyl 2‐(substituted benzylthio)‐4‐(3′‐(ethoxycarbonyl)‐biphenyl‐4‐yl)‐6‐methyl‐1,4‐dihydropyrimidine‐5‐carboxylate derivatives was synthesized. The newly synthesized compounds were characterized by 1H‐NMR, mass and C, H, N analyses. All newly synthesized compounds were screened for their antibacterial (Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, Streptococcus pyogenes and Klebsiella pneumoniae) and antifungal (Aspergillus flavus, Aspergillus fumigatus, Candida albicans, Penicillium marneffei and Trichophyton mentagrophytes) activity. The results revealed that all synthesized compounds have a significant biological activity against the tested microorganisms. Compounds 8a, 8b, 8c, 8e, 8f, 8i, and 8j exhibited good antimicrobial activity.

Novel 2-(1-(substitutedbenzyl)-1H-tetrazol-5-yl)-3-phenylacrylonitrile derivatives: synthesis, in vitro antitumor activity and computational studies

This work describes the two-step synthesis of new series of 2-(1-(substitutedbenzyl)-1H-tetrazol-5-yl)-3-phenylacrylonitrile derivatives (6a–k) starting from substituted benzyl halides (5a–k) and 3-phenyl-2-(1H-tetrazol-5-yl)acrylonitrile (4). Initially, compound 4 was synthesized using benzaldehyde, malononitrile and sodium azide. All the synthesized compounds were obtained in good yields and were characterized using 1H NMR, 13C NMR, FTIR and HRMS spectral data. The new compounds (6a–k) were evaluated for their potential in vitro antitumor activity against four human cancer cell lines (MCF-7, CaCO2, HeLa and SkBr3) by MTT assay. The most potent compounds 6b, 6h and 6j show good activity (IC50 values) relative to 5-fluorouracil, with potential to be antitumor agents. Compounds 6a, 6c, 6g, 6f and 6k showed moderate activity. The best performing three compounds (6b, 6h and 6j) were evaluated for in silico analysis on the PharmMapper web server, and the human mitogen-activated protein kinase 1 (MEK-1) enzyme was recognized as the main target protein. MEK-1 inhibition by these compounds was further confirmed by the docking study to corroborate the target.Graphical Abstract