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Journal of Chemical Sciences
Journal Prestige (SJR): 0.352  Citation Impact (citeScore): 1 Number of Followers: 22  Partially Free JournalISSN (Print) 0974-3626 - ISSN (Online) 0973-7103 Published by Springer-Verlag  [2469 journals]
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- Impact of iodide ions in the transformation of Cu nanostructures from
one-dimensional nanowires to two-dimensional microplates-
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Abstract: Controlling the shape of a metal nanostructure allows to control its properties, yet the processes that induce solution-phase anisotropic growth of metal nanostructures are still a mystery. Though the iodide ion is well-known as a shape-directing agent, the study emphasizes the role of alkylamine in the shape-shifting of 1D Cu nanowires to 2D Cu nanoplates in conjunction with the iodide source. The role of iodide and Cu precursor sources for the production of 2D microplates is also highlighted in this study. Graphical abstract In the presence of alkylamine, iodide ions derived from ionic sources (HI and KI) create 2D microplates, whereas molecular iodine produces wafer-like Cu nanostructures. Cu microplates, on the other hand, cannot be made from CuI in the presence of alkylamine, demonstrating the importance of the precursor's binding strength in the production of Cu microplates.
PubDate: 2022-05-14
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- In situ generated superacid BF3–H2O catalyzed alkylation of p-quinols
with diaryl carbinols leading to triarylmethanes-
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Abstract: In this paper, a highly efficient and sustainable synthesis of triarylmethanes through the dehydrative coupling of p-quinols with diaryl carbinols is presented. The catalyst involved in this protocol is in situ generated superacid BF3–H2O from BF3–OEt2. Therefore, moisture has been used as an efficient initiator in this reaction system. A variety of diaryl carbinols and p-quinols have been investigated and found to be compatible to give the triarylmethanes in yields up to 96%. Graphical abstract
PubDate: 2022-05-05
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- ZIF-8 prepared in ionic liquid microemulsions for efficient capture of
phosphate from water-
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Abstract: A high-efficiency adsorbent ZIF-8 was successfully prepared in a microemulsion system provided by an ionic liquid, which showed excellent potential for removing phosphate from water. The properties of the adsorbents were determined by several characterization methods, such as X-ray diffraction (XRD), infrared spectroscopy (FTIR) and Brunauere-Emmette-Teller (BET) et al. The results confirmed that ZIF-8 prepared in the ionic liquid microemulsion (ZIF-8-ILM) has a smaller particle size compared with that prepared in an aqueous solution. Moreover, the ZIF-8-ILM holds a high BET specific surface area and pore volume, as well as the textural meso- and macro-porosities formed by inter-particle voids. Based on these traits, the ZIF-8-ILM exhibit excellent adsorption capacity for phosphate, as evidenced by a maximum adsorption capacity of 178.99 mg/g was obtained. In addition, the capture of phosphate on ZIF-8-ILM was quite quickly and reached equilibrium within 60 min. Graphical abstract A high-efficiency adsorbent ZIF-8 was successfully prepared in a microemulsion system provided by an ionic liquid. The ZIF-8 materials prepared not only had high BET specific surface area and pore volume but also exhibited hierarchical pore structure, which showed excellent potential for removing phosphate from water.
PubDate: 2022-05-03
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- Facile, sustainable and unassisted plain water oxidation on
Au/Ce0.9Ti0.1O2 nanorods in direct sunlight-
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Abstract: Impressive rate of solar water oxidation to molecular oxygen (O2) has been demonstrated on nanorods (NRs) of Ce0.9Ti0.1O2 (CT-NR) and Au-deposited CT-NR (Au-CT-NR) photocatalysts with a sacrificial agent (Fe3+) and in plain water in one sun condition, direct sunlight and with λ ≥ 455 nm. Probably the highest O2 yield of 11 mmol/h.g was observed with Au-CT-NR thin film in plain water in direct sunlight, with no sacrificial agent or applied potential. Photoelectrochemical measurements demonstrate a marked reduction in oxidation onset potential of Au-CT-NR by 150 mV with stable photocurrent (0.75 mA/cm2), compared to CT-NR (0.23 mA/cm2), indicating the operative of plasmon-induced resonant energy transfer (PIRET) process. Effective electron quenching by nanogold and hence low recombination in the depletion region is a critical step for the observation of a high rate of oxygen evolution. In addition to this, a predominant change in the nature of the valence band from O-2p dominated on CeO2 to Ce-4f dominated with CT-NR (due to Ti4+ introduction in CeO2), the efficient light absorption of photocatalysts in thin-film form, functional and effective PIRET process, and facile EF alignment, enhances the oxygen evolution with Au-CT-NR in direct sunlight and make it highly sustainable. A possible mechanism of water oxidation is proposed from the observed experimental findings. Graphical abstract Extraordinary water oxidation capacity to O2 in sunlight was achieved with a thin-film form of Au-CeTiO2-NR by efficient light absorption followed by effective electron trapping in gold. This minimizes charge recombination and hence minority carriers were efficiently utilized. Reduction in overpotential, Fermi level equilibration and PIRET process due to nano-gold significantly improve the water oxidation capacity in a sustainable manner.
PubDate: 2022-04-30
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- Insights into the insertion reaction mechanism of phosphenium cation and
oxirane: a theoretical study-
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Abstract: The mechanism of insertion reaction between phosphenium cation and phosphindene with oxirane has been investigated theoretically to better understand the reactivity for the valence isoelectronic of carbene. Phosphenium cation acts as an electrophilic reagent and accepts σ electrons of oxirane to form a complex in the first combination step. The greater the positive charge on phosphorus in phosphenium cation, the more stable the formed complex is. The introduction of substituents will decrease the positive charge on phosphorus in phosphenium cation. The order of positive charge on phosphorus is HP+-F > HP+-OH > HP+-NH2, which is consistent with their Lewis acidities. The complex transforms to a four-membered ring product via a transition state in the second insertion step. The product is more stable than the complex due to the decrease of ring extension. Graphical abstract Phosphenium cation acts as an electrophilic reagent and accepts σ electrons of oxygen in oxirane to form a four-membered ring product. The introduction of substituents will decrease the positive charge on phosphorus in phosphenium cation, which reduced the stability of the products.
PubDate: 2022-04-27
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- Synthesis, characterization and photophysical studies of the flavopeptide
conjugates as model for the covalently linked flavoenzymes-
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Abstract: Here, we have demonstrated an easy and efficient synthetic route for the synthesis of the flavo-peptide conjugates as model for the naturally occurring covalently linked flavoenzymes. A judicially functionalized flavin analogue was used for the coupling reaction with the pre-synthesized peptidic motifs using solution-phase chemistry. Representative examples using mono-, di- and tripeptides were reported to couple with the C7-position of the flavin moiety to showcase the generic nature of the synthetic strategy. Further photophysical investigation including quantum yield measurements, concentration-dependent studies and fluorescence quenching experiments reveal the intramolecular nature of the charge transport process in cases where tyrosine is present, similar to that found in the natural counterpart. Graphical abstract This manuscript discusses a simple/efficient approach for the synthesis of flavopeptide conjugates as a true model for covalently-liked-flavoenzymes. Coupling reaction between the suitably functionalized flavin moiety and the pre-synthesized peptide entities was envisaged and undertaken to prove the generality of the approach. Further photophysical investigation including quantum yield measurements, concentration-dependent studies and fluorescence quenching experiments reveal the intramolecular nature of the charge transport process in cases where tyrosine is present, similar to that found in the natural counterpart. Such a synthetic flavopeptide model may provide a further investigation to provide an insight into the corresponding biological phenomenon.
PubDate: 2022-04-27
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- Applying polypharmacology approach for drug repurposing for SARS-CoV2
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Abstract: Exploring the new therapeutic indications of known drugs for treating COVID-19, popularly known as drug repurposing, is emerging as a pragmatic approach especially owing to the mounting pressure to control the pandemic. Targeting multiple targets with a single drug by employing drug repurposing known as the polypharmacology approach may be an optimised strategy for the development of effective therapeutics. In this study, virtual screening has been carried out on seven popular SARS-CoV-2 targets (3CLpro, PLpro, RdRp (NSP12), NSP13, NSP14, NSP15, and NSP16). A total of 4015 approved drugs were screened against these targets. Four drugs namely venetoclax, tirilazad, acetyldigitoxin, and ledipasvir have been selected based on the docking score, ability to interact with four or more targets and having a reasonably good number of interactions with key residues in the targets. The MD simulations and MM-PBSA studies showed reasonable stability of protein-drug complexes and sustainability of key interactions between the drugs with their respective targets throughout the course of MD simulations. The identified four drug molecules were also compared with the known drugs namely elbasvir and nafamostat. While the study has provided a detailed account of the chosen protein-drug complexes, it has explored the nature of seven important targets of SARS-CoV-2 by evaluating the protein-drug complexation process in great detail. Graphical abstract Drug repurposing strategy against SARS-CoV2 drug targets. Computational analysis was performed to identify repurposable approved drug candidates against SARS-CoV2 using approaches such as virtual screening, molecular dynamics simulation and MM-PBSA calculations. Four drugs namely venetoclax, tirilazad, acetyldigitoxin, and ledipasvir have been selected as potential candidates.
PubDate: 2022-04-22
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- Design and synthesis of amino acid derivatives containing hydantoin and
thiazolidine moieties-
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Abstract: We report a simple synthetic approach to N-methyl spiro hydantoin and thiazolidine containing amino acid derivatives by coupling 1,2,4,5-tetrakis(bromomethyl) benzene with ethyl isocyanoacetate (EICA) as a glycine equivalent. Normally, α-amino acids are derived from hydantoin, here we have incorporated hydantoin and amino acid moieties in the same molecules. Access to such hybrid molecules opens up new possibilities in medicinal chemistry. Graphical abstract Herein, we developed a facile synthetic strategy to spiro hydantoin and thiazolidine derivatives bearing unusual amino acid skeleton through the coupling of 1,2,4,5-tetrakis(bromomethyl) benzene with ethyl isocyanoacetate (EICA) as a glycine equivalent.
PubDate: 2022-04-22
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- The synthesis of sutezolid and eperezolid using proline catalyzed
α-aminoxylation of an aldehyde-
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Abstract: The given article describes the synthesis of 2-Oxazolidinone ring via proline catalyzed stereoselective α-aminoxylation of aldehyde. 2-Oxazolidinone ring is a common core structure during the synthesis of oxazolidinones class molecules. Using this simple, facile and efficient methodology, Linezolid and sutezolid were prepared using asymmetric catalysis. Graphical abstract Selective α-aminoxylation was achieved on corresponding aldehyde with great enantiomeric excess to get intermediate (5) using catalytic amount of low cost proline. The oxazolidinone ring was then constructed on common intermediate (5) which was then further converted to Oxazolidinone class compounds like Sutezolid and Eperezolid.
PubDate: 2022-04-20
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- Self-assembled discrete and polymeric cobalt(II) complexes of a
carboxylate appended tripodal tetradentate ligand: reactivity with aerial
dioxygen or aqueous hydrogen peroxide-
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Abstract: Three new cobalt(II) complexes [Co(µ2-L)]3(ClO4)3.2H2O, 1, [Co(L)(NO3)], 2 and {[Co(µ2-L)(MeOH)](BPh4).(MeOH)}n, 3 are prepared where L stands for 2-(bis(pyridin-2-ylmethyl)amino)acetate. Single crystal X-ray diffraction analysis confirmed the trinuclear core for 1, and 1-D polymeric structure for 3. It is proposed that these complexes are largely mononuclear in solution state. Reactivity of the complexes with aerial dioxygen, in presence of Et3N, invariably produced a common complexed cation [Co(L)(pic)]+ where pic stands for picolinate. The novelty of the finding is in terms of the presence of both intact ligand (i.e L) and a fragment of the ligand (i.e. pic) in the same complex. Crystal structures of the isolated complexes [Co(L)(pic)](ClO4), 4a and [Co(L)(pic)](NO3), 4b confirmed the solid state structures. The Co(II) center of a complex is oxidized to Co(III) and the bound ligand moiety afforded a picolinate unit (due to oxidative Cpicolyl-Namine bond cleavage). The picolinate unit then connects with another molecule of a Co(III) complex containing L in its original form. Oxidation of a representative complex using H2O2 also resulted [Co(L)(pic)]+, but a stable binuclear dihydroxo bridged Co(III) complex [Co(L)(µ2-OH)]2(ClO4)2, 5 was formed when controlled amount of H2O2 (1 equiv) was employed. Graphical abstract
Synopsis: Three new Co(II) complexes of 2-(bis(pyridin-2-ylmethyl)amino)acetate (L) are prepared. Reactivity of the complexes with aerial dioxygen, in presence of Et3N, invariably produced Co(III) complexes having the common complexed cation [Co(L)(picolinate)]+. Picolinate is generated due to the oxidative cleavage of bound L.
PubDate: 2022-04-16
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- Superior efficacy of biocomposite membranes of chitosan with
montmorillonite and kaolin vs pure chitosan for removal of Cu(II) from
wastewater-
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Abstract: The development of environment-friendly products and processes is the need of the hour. Both chitosan and clays are naturally available abundant materials. The application of clays, kaolin and montmorillonite, for water treatment, constitutes an important area of research. The use of membranes has become favorable over technologies like distillation and extraction. This paper reports preparation of chitosan membranes with kaolin and montmorillonite by a simple solvent evaporation technique. The membranes were further characterized using various analytical techniques like SEM, XRD, TGA-DSC and FTIR. An aqueous solution of Cu(II) was adsorbed using these membranes and their effectiveness summarized. Effect of variables like contact time and initial dye concentration were studied for adsorption. The membranes could be reused after regeneration. Chitosan/montmorillonite membranes (CMM) show 86% removal of Cu ions with the adsorption following pseudo 2nd order isotherm. A simple eco-friendly biocomposite membrane is very effective in copper removal from waste water. Graphical abstract
PubDate: 2022-04-16
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- 2-Mercaptobenzimidazole ligand-based models of the [FeFe] hydrogenase:
synthesis, characterization and electrochemical studies-
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Abstract: Reaction of Fe3(CO)12 and 2-mercaptobenzimidazole leads to the formation of a triiron sulphur cluster [Fe3(C7H6N2)(µ3-S)2(CO)8] 1 and a diiron monothiolate-bridged complex [Fe2(µ-2-mercaptobenzimidazole)2(CO)6] 2. The structures of the complexes were confirmed by various spectroscopic techniques (NMR, FTIR, UV-Vis), elemental analysis and mass spectrometry. FTIR spectra of 1 and 2 (in CH2Cl2) displayed peaks at 2069, 2022, 2006, 1965 and 2070, 2002, 1963 cm−1, respectively indicating the presence of terminal carbonyls in the two complexes. Based on cyclic voltammetric measurements, complexes 1 and 2 were found to catalyze the reduction of trifluoroacetic acid to produce dihydrogen (in CH3CN) at −1.68 V and −1.58 V vs. Fc/Fc+, respectively. Graphical abstract The reaction of Fe3(CO)12 with 2-mercaptobenzimidazole led to the formation of an unusual triiron carbene cluster as the major product and a diiron monothiolate complex as the minor product. The di- and triiron clusters displayed electrocatalytic activity in acetonitrile in the presence of either acetic acid or trifluoroacetic acid as proton sources.
PubDate: 2022-04-08
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- Why do some reactions possess similar reaction rate in wildly different
viscous media' A possible explanation via frequency-dependent friction
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Abstract: We explore herein the interconnection between the collective intermolecular solvent modes (CIM) and ultrafast reaction rate, assuming that frequency-dependent solvent friction controls the rate of such reactions. We attempt to find a possible explanation for the observed near-insensitivity of ultrafast reaction rates (for example, charge transfer reaction) to the medium viscosity. Results are presented here by employing an analytical scheme that estimates the high-frequency solvent frictional response. Representative room temperature reaction media considered here are an ionic liquid (BMIMPF6, \(\eta \sim 310\mathrm{ cP}\) ), a dipolar solvent (ethanol, \(\eta \sim 1.09\mathrm{ cP}\) ) and a deep eutectic solvent (Acetamide+ LiBr, \(\eta \sim 1950\mathrm{ cP}\) ). It is found that the wavenumber and frequency-dependent rotational friction, \({\Gamma }_{R}(\kappa ,z)\) , estimated by using the available experimental dielectric relaxation (DR) data for the ionic liquid and the deep eutectic solvent (DES), cannot predict the viscosity independence of \({\Gamma }_{R}(\kappa ,z)\) at high frequency. Missing dispersion in the DR data of the DES appears to be critical and incorporation of this missing amplitude via collective solvent intermolecular modes centered around 100 cm-1 markedly improves the high-frequency behaviour of \({\Gamma }_{R}\left(\kappa ,z\right).\) Subsequently, the calculated \({\Gamma }_{R}(\kappa ,z)\) for these solvents at high frequency exhibits near-insensitivity to medium viscosity and explain the viscosity independence of ultrafast reaction rates. Graphical abstract Comparison of the frequency dependent rotational friction among three different solvent systems considered – normal liquid (ethanol), deep eutectic solvent (acetamide/LiBr) and ionic liquid ([BMIM][BF6]). Note the high frequency friction values for these solvents are very similar, although their zero frequency values differ quite considerably because of widely different viscosities.
PubDate: 2022-04-01
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- Electrochemically co-deposited silicate sol–gel/PdAu alloy
nanostructures and their application in electrocatalytic methanol
oxidation-
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Abstract: Bimetallic PdAu alloy nanostructures incorporated ethylene diamine functionalized silicate sol-gel (ES) nanocomposite materials on indium-tin-oxide (I) electrodes (I/ES-PdAu) were prepared by facile electrochemical method. X-ray diffraction patterns confirmed the formation of single-phase bimetal PdAu alloy nanostructures at the electrode. X-ray photoelectron spectroscopy analysis confirmed the existence of a zero oxidation state of Pd and Au metals at the I/ES-PdAu electrode. Morphology analysis revealed the formation of anisotropic nanostructures of Au, Pd and PdAu alloy nanostructures with different sizes and shapes at the modified electrodes. Electrocatalytic methanol oxidation reaction (MOR) was studied and enhanced methanol oxidation activity was observed at the bimetallic I/ES-Pd75Au25 and I/ES-Pd50Au50 modified electrodes when compared to pristine I/ES-Pd100, I/Pd100 and I/ES-Au100 modified electrodes. The I/ES-Pd75Au25 modified electrode was found to be the best electrocatalyst which showed lower overpotential with higher mass activity (0.144 A/mgPd) for MOR. Interestingly, when Pd was combined with Au in the presence of ES silicate sol-gel the bimetallic PdAu alloy nanomaterials showed enhanced MOR activity. The MOR current observed at the I/ES-Pd75Au25 electrode was nearly 1.8 times higher than that of the I/Pd75Au25 electrode without ES silicate sol-gel. The stability of the I/ES-Pd75Au25 electrode was tested by scanning 200 continuous cycles and the catalytic current was found to decrease only <5%. Graphical abstract Electrochemically co-deposited PdAu bimetallic materials embedded in N-[3-(trimethoxysilyl) propyl]ethylenediamine silicate (ES) sol-gel modified electrode (I/ES-Pd75Au25) displayed 8.7 and 3.2 times higher methanol oxidation current and mass activity when compared to the pristine I/ES-Pd100 modified electrode due to ES silicate sol-gel supported mass interaction between PdAu alloy nanostructure with the analyte.
PubDate: 2022-04-01
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- Synthesis and physicochemical characterization of PMMA and PNIPAM based
block copolymers by using PEG based macro RAFT agents-
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Abstract: Polyethylene glycol (PEG) based macro-RAFT agents were synthesized by the condensation reaction of PEG (Mn: 2000 Da and 8000 Da) with the carboxylic acid functionalized trithiocarbonate [S-Dodecyl-S′-(α,α′-dimethyl-α″-acetic acid) tritiocarbonate (DDMAT)] using dicyclohexylcarbodiimide (DCC)/4-(dimethylamino) pyridine (DMAP) as catalyst at room temperature. Then, N-isopropylacrylamide (NIPAM) and methyl methacrylate (MMA) monomers were polymerized, respectively, using synthesized new macro-RAFT agents and N, N′-azo bis isobutyronitrile (AIBN) as the initiator. In all RAFT polymerizations, dispersity values were found in the range of 1.04 to 1.47, which showed that RAFT polymerization was applied successfully. The synthesized polymers were characterized using Fourier Transform Infrared Spectroscopy (FTIR), Proton Nuclear Magnetic Resonance Spectroscopy (1H-NMR), Gel Permeation Chromatography (GPC) and Differential Scanning Calorimetry (DSC) techniques. The fractured surface images of PEG-b-PMMA block copolymers were obtained by Scanning Electron Microscopy (SEM). SEM images PEG-b-PMMA block copolymers have shown that the copolymers have a microporous structure. In addition, the swelling ratios and LCST values of the PEG-b-PNIPAM block copolymers were measured which were found to be very high. The lower critical temperature values of the copolymers are closer to that of the PNIPAM homopolymer, 32 °C, indicating its usability in drug delivery systems. Graphical abstract Macro-RAFT agents were successfully synthesized in high yield by reacting S-dodecyl-S′-(α,α′-dimethyl-α″-acetic acid) tritiocarbonate (DDMAT) (R-2) with polyethylene glycols (Mn: 2000 Da and 8000 Da, respectively). Subsequently, the monomers methyl methacrylate (MMA) and N-isopropylacrylamide (NIPAM) were polymerized respectively using synthesized macro-RAFT agents. SEM images of PEG-b-PMMA block copolymers have shown that the copolymers have a microporous structure. The critical temperature values of the PEG-b-PNIPAM block copolymers are closer to that of the PNIPAM homopolymer, 32 °C, indicating their usability in drug delivery systems.
PubDate: 2022-03-28
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- W/HAP catalysed N-oxidation of tertiary amines with H2O2 as an oxidant
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Abstract: Synthesis of several N-oxides with tungsten exchanged hydroxyapatite (W/HAP) in the presence of 30% hydrogen peroxide (H2O2) as an oxidant is presented. A process with aqueous H2O2, a cheap and clean oxidant with an active catalyst is developed to reduce waste production and meet the requirements of green chemistry. Several tertiary amines have been efficiently oxidized to their corresponding N-oxides with excellent yields. The as-synthesized catalyst (W/HAP) is characterized using BET, FTIR, SEM, ICP-OES and XRD. Effect of catalyst loading , temperature and oxidants were studied. A kinetic model has been developed to determine the reaction rate at different temperatures and activation energy for the model reaction. Graphical abstract Synopsis. Synthesis of several N-oxides using tungsten exchanged hydroxyapatite (W/HAP) in the presence of 30% hydrogen peroxide (H2O2) as an oxidant is presented. A process with aqueous H2O2, a cheap and clean oxidant with an active catalyst is developed to reduce waste production and meet the requirements of green chemistry.
PubDate: 2022-03-28
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- Amendment to: Structural changes at complexing of 3d (4d) elements with
"template" tetradentate ligand –
1,8-diimino-1,8-dimercapto-3,6-diazaoctadien-3,5-dithione-2,7: DFT
analysis-
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Abstract: Graphical abstract This publication is a correction to an earlier paper, N 123, published in the Journal of Chemical Science, 2021, Volume 133, Number 4.
PubDate: 2022-03-23
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- Catalytic properties of SmMnO3/cordierite monolithic catalysts: acid
treatment and calcination process optimization using response surface
methodology-
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Abstract: This work focuses on the optimization of the acid treatment and calcination process factors affecting the catalytic performance of the SmMnO3/cordierite monolithic catalyst for o-xylene oxidation, using response surface methodology (RSM) analysis. A central composite rotatable design (CCRD) was used to statistically visualize the complex interactions of acid treatment time, acid concentration, calcination temperature, and calcination time for T50 and T90 values. And the validity of the models developed was verified by experiments. Statistics showed the most significant process factor which affects catalytic combustion activity is acid treatment time. It is also shown that the catalytic activity increases with increasing acid treatment time or acid concentration and that a moderate calcination temperature or time is required to increase the catalytic activity. Furthermore, it was found through SEM analysis that the acid treatment process significantly impacts the morphology of the SmMnO3/cordierite monolithic catalysts. Thus, RSM is an effective technique for estimating the catalytic activity of monolithic catalysts. Graphical abstract In this work, the effects of acid treatment and calcination process on the catalytic performance of SmMnO3/cordierite monolithic catalyst for o-xylene oxidation were based on response surface methodology (RSM) through presenting a mathematical modeling and factorial analysis.
PubDate: 2022-03-19
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- Ultrasound-assisted efficient synthesis and antimicrobial evaluation of
pyrazolopyranopyrimidine derivatives using starch functionalized magnetite
nanoparticles as a green biocatalyst in water-
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Abstract: A Highly efficient and environmentally friendly route for the one-pot multi-component construction of biologically active pyrazolopyranopyramidine derivatives by the reaction of aromatic aldehydes, hydrazine hydrate, ethyl acetoacetate, and barbituric acid under ultrasound has been evolved. The reaction is promoted by starch@Fe3O4 at room temperature using water as solvent. The key features of the present reaction are the excellent yield of products, mild reaction condition, without column chromatography, reusability, and magnetically separable catalyst. The characterization of prepared catalyst and products were performed by XRD, Fourier transforms infrared spectra (FT-IR), thermal analysis (TGA), TEM, FE-SEM, EDAX, vibrating sample magnetometer (VSM) techniques, melting point, 13CNMR, and 1HNMR analysis. The obtained products (5a–5l) were screened for antimicrobial activity. According to results, synthesized compounds exhibited potent antimicrobial activities against fungi C. albicans, Gram-positive bacteria S. aureus and S. phyogens, and Gram-negative bacteria E. coli and P. aeruginosa. Graphical abstract A highly efficient and environmentally friendly route for the one-pot multi-component construction of biologically active pyrazolopyranopyramidine derivatives by the reaction of aromatic aldehydes, hydrazine hydrate, ethyl acetoacetate, and barbituric acid under ultrasonication has been evolved. The reaction is promoted by starch@Fe3O4 at room temperature using water as solvent. The key features of the present reaction are the excellent yield of products, mild reaction condition, without column chromatography, reusability, and magnetically separable catalyst.
PubDate: 2022-03-19
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- Preparation of nitrogen-doped porous carbon modified by iron carbide and
its application in an oxygen reduction reaction-
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Abstract: A high-efficiency carbon-based metal catalyst was prepared using inexpensive raw materials and a simple synthetic method to replace the commercial platinum-based catalyst in oxygen reduction reaction (ORR). In this article, clay was used as the template, and residual organic matter after oil adsorption was used as the carbon source and the nitrogen source, respectively. Through ion adsorption, nitrogen-doped porous carbon catalyst (Fe3C/NC) modified by iron carbide was synthesized by high-temperature pyrolysis and etching of clay mineral template. Fe3C/NC was characterized by Fourier-transform infrared spectroscopy (FT-IR), High-resolution transmission electron microscopy (TEM) and X-ray diffractometer. Further experiment showed that this catalyst had good electrochemical activity for ORR. Graphical abstract In this paper, we use the organic matter in the waste clay as the carbon source and nitrogen source and use the characteristics of clay in the waste clay to introduce iron ions into the reaction. After high-temperature calcination, we get Fe3C/NC composite. Fe-N co-doping can expose more graphite defects and more active sites, which can also improve the electrocatalytic performance of ORR.
PubDate: 2022-03-18
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