Arghya Dutta

One-pot thioetherification of aryl halides with thiourea and benzyl bromide in water catalyzed by Cu-grafted furfural imine-functionalized mesoporous SBA-15

Surface functionalization of SBA-15 followed by its reaction with Cu(OAc)(2) has been carried out to develop a new Cu-grafted functionalized mesoporous material, which catalyzes one-pot three component coupling of different aryl halides with thiourea and benzyl bromide in aqueous medium to produce aryl thioethers in very good yields (80-88%).

Self-assembled mesoporous γ-Al2O3 spherical nanoparticles and their efficiency for the removal of arsenic from water.

We report a highly efficient synthetic strategy for self-assembled mesoporous γ-Al(2)O(3) materials using sodium salicylate as template. The mesoporous γ-Al(2)O(3) samples synthesized following this strategy have high surface areas (231-497 m(2)g(-1)), consist of crystalline tiny spherical nanoparticles of dimensions ca. 2-10nm and showed high affinity for the adsorption of arsenic from the contaminated aqueous solutions. Efficient synthesis strategy, exceptionally high surface area and high adsorption efficiency of these mesoporous γ-Al(2)O(3) materials for the dissolved arsenic from the contaminated aqueous solutions (in the form of oxyanions of arsenic) could find potential utility in the purification of polluted water.

Synthesis of 5‐Hydroxymethylfurural from Carbohydrates using Large‐Pore Mesoporous Tin Phosphate

A large-pore mesoporous tin phosphate (LPSnP-1) material has been synthesized hydrothermally by using Pluronic P123 as the structure-directing agent. The material is composed of aggregated nanoparticles of 10-15 nm in diameter and has a BET surface area of 216 m(2)  g(-1) with an average pore diameter of 10.4 nm. This pore diameter is twice as large as that of mesoporous tin phosphate materials synthesized through the surfactant-templating pathways reported previously. LPSnP-1 shows excellent catalytic activity for the conversion of fructose, glucose, sucrose, cellobiose, and cellulose to 5-hydroxymethylfurfural (HMF) in a water/methyl isobutyl ketone biphasic solvent to give maximum yields of HMF of 77, 50, 51, 39, and 32 mol %, respectively, under microwave-assisted heating at 423 K. Under comparable reaction conditions, LPSnP-1 gives 12 % more HMF yield than a small-pore mesoporous tin phosphate catalyst that has an identical framework composition. This confirms the beneficial role of large mesopores and nanoscale particle morphology in catalytic reactions that involve bulky natural carbohydrate molecules.

Hierarchically porous titanium phosphate nanoparticles: an efficient solid acid catalyst for microwave assisted conversion of biomass and carbohydrates into 5-hydroxymethylfurfural

A new hierarchical macro/mesoporous titanium phosphate MTiP-1 has been synthesized through a slow evaporation method by using titanium isopropoxide and orthophosphoric acid as inorganic sources and pluronic P123 as the structure directing agent. Powder X-ray diffraction, FT-IR and electron dispersive spectroscopy (EDS) were used to analyze the framework, structure and composition of the material. The N2 adsorption/desorption isotherm of this material is of type IV, which is characteristic of a mesoporous material and it shows a Brunauer–Emmett–Teller (BET) surface area of 193 m2 g−1 together with an average pore dimension of ca. 7 nm. From scanning electron microscopic (SEM) images it is seen that there is hierarchical porosity in MTiP-1 and the mesoporosity of this material arises due to self-aggregation of tiny spherical particles of dimension ca. 15–20 nm. Transmission electron microscopic (TEM) images show the existence of randomly distributed mesopores in the material. This MTiP-1 material shows very good catalytic activity in the microwave assisted conversion of biomass and carbohydrates into 5-hydroxymethylfurfural (HMF). The catalytic reactions are carried out in different solvents like water, water–methylisobutyl ketone (MIBK), MIBK and dimethylacetamide (DMA)–LiCl. MTiP-1 also catalyzes the direct conversion of cellulose substrates and lignocellulosic biomass, sugarcane bagasse, into HMF.

Heterogeneous ditopic ZnFe2O4 catalyzed synthesis of 4H-pyrans: further conversion to 1,4-DHPs and report of functional group interconversion from amide to ester

Highly stable, environmentally benign ZnFe2O4 nanopowder was prepared, characterized and applied in the one-pot, three-component synthesis of 4H-pyrans in water. The ZnFe2O4 catalyst provides both acidic (Fe3+) and basic functionalities (O2−) as the reaction requires. The advantages of this method lie in its simplicity, cost effectiveness, environmental friendliness and easier scaling up for large scale synthesis. Water was exploited both as a reaction medium as well as a medium for synthesis of the catalyst. Moreover, water was the only byproduct. The present report puts forward an application of 4H-pyrans for the synthesis of 1,4-DHPs. This is the first attempt towards the synthesis of 4H-pyran-3-carboxylate from 4H-pyran-3-carboxamide. The corresponding functional group interconversion from amide to ester is rare in organic synthesis.

Facile C–S coupling reaction of aryl iodide and thiophenol catalyzed by Cu-grafted furfural functionalized mesoporous organosilica

A new functionalized mesoporous organosilica has been designed via Schiff-base condensation of furfural and 3-aminopropyltriethoxy-silane (APTES) followed by its hydrothermal co-condensation with tetraethylorthosilicate (TEOS) in the presence of a cationic surfactant CTAB. Subsequent reaction of this mesoporous organosilica with Cu(OAc)(2) in absolute ethanol leads to the formation of a new Cu(II)-grafted mesoporous organosilica catalyst 1. Powder XRD, HR TEM, FE SEM, N(2) sorption and FT IR spectroscopic tools are used to characterize the materials. This Cu-anchored mesoporous material acts as an efficient, reusable catalyst in the aryl-sulfur coupling reaction between aryl iodide and thiophenol for the synthesis of value added diarylsulfides.

Hybrid porous tin(IV) phosphonate: an efficient catalyst for adipic acid synthesis and a very good adsorbent for CO2 uptake.

A new porous organic-inorganic hybrid tin phosphonate material has been synthesized hydrothermally, which shows a Brunauer-Emmett-Teller surface area of 723 m(2) g(-1) and it adsorbs 4.8 mmol g(-1) CO(2) at 273 K and 5 bar pressure. The material also shows remarkable catalytic activity in one-pot liquid phase oxidation of cyclohexanone to adipic acid under eco-friendly conditions.

Template-Free Synthesis of a Porous Organic–inorganic Hybrid Tin(IV) Phosphonate and Its High Catalytic Activity for Esterification of Free Fatty Acids

Here we have synthesized an organic-inorganic hybrid mesoporous tin phosphonate monolith (MLSnP-1) with crystalline pore walls by a template-free sol-gel route. N2 sorption analysis shows Brunauer-Emmett-Teller (BET) surface area of 347 m2 g(-1). Wide-angle powder X-ray diffraction (PXRD) pattern shows few broad diffraction peaks indicating crystalline pore wall of the material. High-resolution transmission electron microscopic (HR TEM) image further reveals the crystal fringes on the pore wall. Framework bonding and local environment around phosphorus and carbon were examined by Fourier transform infrared (FT IR) spectroscopy and solid-state MAS NMR spectroscopy. The material exhibits remarkable catalytic activity for esterification of long chain fatty acids under mild reaction conditions at room temperature.

A structured three-dimensional polymer electrolyte with enlarged active reaction zone for Li-O2 batteries

The application of conventional solid polymer electrolyte (SPE) to lithium-oxygen (Li–O2) batteries has suffered from a limited active reaction zone due to thick SPE and subsequent lack of O2 gas diffusion route in the positive electrode. Here we present a new design for a three-dimensional (3-D) SPE structure, incorporating a carbon nanotube (CNT) electrode, adapted for a gas-based energy storage system. The void spaces in the porous CNT/SPE film allow an increased depth of diffusion of O2 gas, providing an enlarged active reaction zone where Li+ ions, O2 gas, and electrons can interact. Furthermore, the thin SPE layer along the CNT, forming the core/shell nanostructure, aids in the smooth electron transfer when O2 gas approaches the CNT surface. Therefore, the 3-D CNT/SPE electrode structure enhances the capacity in the SPE-based Li–O2 cell. However, intrinsic instability of poly(ethylene oxide) (PEO) of the SPE matrix to superoxide (O2·−) and high voltage gives rise to severe side reactions, convincing us of the need for development of a more stable electrolyte for use in this CNT/SPE design.

Synthesis of Hierarchical Mesoporous Mn–MFI Zeolite Nanoparticles: A Unique Architecture of Heterogeneous Catalyst for the Aerobic Oxidation of Thiols to Disulfides

An efficient procedure for aerobic oxidation of thiols to disulfides catalyzed by new self‐assembled hierarchical mesoporous Mn–MFI in the presence of air under solvent‐free conditions as well as in aqueous medium is reported. The mesoporosity and Mn4+ loading, together with a highly crystalline microporous pore wall structure of the MFI framework were achieved through a newly designed hydrothermal process. This hydrothermal approach leads to hierarchical self‐assembled mesoporous zeolite structures through isomorphous substitution of Si by Mn and Al. It is shown that Mn‐containing mesoporous zeolites are capable to form disulfide bonds from thiols in the presence of air. The zeolitic materials were characterized by XRD, field‐emission scanning electron microscopy, high‐resolution TEM, X‐ray photoelectron spectroscopy, 29Si NMR, 27Al NMR, and EPR spectroscopy, as well as AAS analysis and N2 sorption studies. N2 sorption analysis revealed high surface areas and narrow pore size distributions (1.2–6.0 nm) for different samples. The mesoporous Mn–ZSM‐5 acted as an efficient heterogeneous catalyst with maximum catalytic activity in the benzenethiol conversion to diphenyldithiol.