Malay Pramanik

A triazine functionalized porous organic polymer: excellent CO2 storage material and support for designing Pd nanocatalyst for C–C cross-coupling reactions

One-pot bottom-up synthesis involving extended aromatic electrophilic substitution on to a pyrrole has been employed for the design of a novel triazine-functionalized porphyrin-based porous organic polymer, TPOP-1. Hydrothermal treatment of 4,4′,4′′-(1,3,5-triazine-2,4,6-triyl)tris(oxy)tribenzaldehyde and pyrrole in glacial acetic acid in the presence of FeCl3 leads to the formation of TPOP-1, which is a highly porous and robust material, and which exhibits a high surface area and bimodal pore sizes ranging from large micropores to mesopores. The presence of porphyrin and triazine functionality within the network structure enables formation of electron-donating basic N-sites at the surface of the porous organic framework and thus favors the adsorption of Lewis acidic CO2 molecules and decoration of the material by palladium nanoparticles at its surface to form Pd-TPOP-1. TPOP-1 showed good CO2 storage capacity (6.2 mmol g−1 or 27.3 wt% at 3 bar/273 K), suggesting its potential application in environmental clean-up. Moreover, this post Pd-functionalized material forms fine colloidal suspensions in organic solvent and exhibits high catalytic activity for Sonogashira cross-coupling of aryl halides with aryl alkynes under mild reaction conditions.

Ordered Mesoporous Cobalt Phosphate with Crystallized Walls toward Highly Active Water Oxidation Electrocatalysts.

A hexagonally ordered mesoporous cobalt phosphate (CoPi) material is prepared by a facile one-pot soft-templating strategy using cetyltrimethylammonium bromide template. Because of its highly accessible surface area and crystalline framework with abundant active sites, the mesoporous CoPi shows a high catalytic activity for the oxygen evolution reaction compared to previously reported noble/transition-metal and nonmetal catalysts.

Controlled Synthesis of Nanoporous Nickel Oxide with Two‐Dimensional Shapes through Thermal Decomposition of Metal–Cyanide Hybrid Coordination Polymers

The urgent need for nanoporous metal oxides with highly crystallized frameworks is motivating scientists to try to discover new preparation methods, because of their wide use in practical applications. Recent work has demonstrated that two-dimensional (2D) cyanide-bridged coordination polymers (CPs) are promising materials and appropriate for this purpose (Angew. Chem. Int. Ed.- 2013, 52, 1235). After calcination, 2D CPs can be transformed into nanoporous metal oxides with a highly accessible surface area. Here, this strategy is adopted in order to form 2D nanoporous nickel oxide (NiO) with tunable porosity and crystallinity, using trisodium citrate dihydrate as a controlling agent. The presence of trisodium citrate dihydrate plays a key role in the formation of 2D nanoflakes by controlling the nucleation rate and the crystal growth. The size of the nanoflakes gradually increases by augmenting the amount of trisodium citrate dihydrate in the reaction. After heating the as-prepared CPs in air at different temperatures, nanoporous NiO can be obtained. During this thermal treatment, organic units (carbon and nitrogen) are completely removed and only the metal content remains to take part in the formation of nanoporous NiO. In the case of large-sized 2D CP nanoflakes, the original 2D flake-shapes are almost retained, even after thermal treatment at low temperature, but they are completely destroyed at high temperature because of further crystallization in the framework. Nanoporous NiO with high surface area shows significant efficiency and interesting results for supercapacitor application.

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.

Organic–inorganic hybrid porous sulfonated zinc phosphonate material: efficient catalyst for biodiesel synthesis at room temperature

A new porous zinc phosphonate material (HZnP-1) has been synthesized via the reaction between p-xylenediphosphonic acid and anhydrous ZnCl2 under hydrothermal and mildly acidic conditions (pH ∼ 5) in the absence of any structure directing agent. The phenyl group of this material has been sulfonated with concentrated sulfuric acid to obtain sulfonic acid functionalized material HZnPS-1. Powder X-ray diffraction (XRD), field emission scanning electron microscopy (FE SEM), N2 sorption, solid state 13C CP MAS and 31P MAS NMR, and FT IR spectroscopic tools are employed to characterize these materials. The crystal structures of both the materials are indexed corresponding to the new orthorhombic phases with unit cell parameters a = 11.00, b = 8.74, c = 14.62 A, α = β = γ = 90° for HZnP-1, and a = 10.65, b = 13.52, c = 15.30 A and α = β = γ = 90° for HZnPS-1. HZnPS-1 showed outstanding catalytic activity and high recycling efficiency for the synthesis of different biodiesel compounds via esterification of long chain fatty acids by using methanol as both reactant and solvent at room temperature. The green and eco-friendly catalytic system described herein can overcome the problem faced by the existing catalytic systems known in biodiesel synthesis, such as drastic conditions (high reaction temperature) and requirement of hazardous organic solvents.

Phosphonic acid functionalized ordered mesoporous material: a new and ecofriendly catalyst for one-pot multicomponent Biginelli reaction under solvent-free conditions.

We report a new ordered 2D hexagonal mesoporous organosilica material (PAFMS-1) bearing phosphonic acid functionality at the surface. This hybrid material showed high Brunauer-Emmett-Teller surface area (565 m(2) g(-1)) and ordered assembly of mesoporoes with an average pore diameter of ca. 2.1 nm. This novel hybrid mesoporous material has been synthesized via cocondensation of (triethoxysilyl)(propyliminomethyl)biphenylmethyl phosphoester (PEFOS) and tetraethyl orthosilicate (TEOS) in the presence of cationic surfactant cetyltrimethylammonium bromide (CTAB) at 373 K. The phosphoester-functionalized organosilane (PEFOS) precursor has been synthesized for the first time by a simple SN2 reaction followed by Suzuki coupling and a Mannich reaction. The material has been characterized by powder X-ray diffraction, N2 sorption, and transmission electron microscopy image analysis, whereas the presence of organic moieties (an aromatic biphenyl ring and an aliphatic side chain), phosphrous, and silicon in the pore wall of the material have been characterized by solid-state magic-angle-spinning NMR, X-ray photoelectron, and Fourier transform infrared (FT-IR) spectroscopic tools. Further, the surface acid strength of the hybrid material has been determined by FT-IR analysis of the samples via temperature-programmed pyridine adsorption studies. The material has been utilized as a reusable heterogeneous catalyst for the synthesis of biologically important and value added multifunctionalized 3,4-dihydropyridin-2-1H-(ones)/3,4-dihydropyridin-2-1H-(thiones) (DHPMs) through a multicomponent Biginelli condensation reaction under solvent-free conditions at 333 K. The phosphonic acid functionalized 2D hexagonal mesoporous material showed much higher catalytic activity in this multicomponent condensation reaction over sulfonic acid functionalized mesoporous silica (MCM-41-SO3H) bearing an aliphatic chain in the hybrid framework.

Organic–inorganic hybrid tinphosphonate material with mesoscopic void spaces: an excellent catalyst for the radical polymerization of styrene

A new porous tinphosphonate HSnP-1 has been synthesized through the reaction of butylene-1,4-diphosphonic acid and SnCl4·5H2O under hydrothermal conditions at 453 K for 3 days in the absence of any structure directing agent. Powder X-ray diffraction, transmission and scanning electron microscopies (TEM and SEM), N2 sorption, solid state 13C CP MAS and 31P MAS NMR, UV-vis and FT IR spectroscopic tools are used to characterize the material. The crystallinity of HSnP-1 is sufficiently high under mildly acidic pH conditions and the crystal structure of the material has been indexed to the tetragonal phase with unit cell parameters a = b = 11.52 A, c = 15.84 A, α = β = γ = 90°. The surface area and the pore volume of the material were 338 m2 g−1 and 0.54 cc g−1, respectively. HSnP-1 showed outstanding catalytic activity in the radical polymerization of styrene at room temperature in the presence of aqueous H2O2 as an initiator under solvent-free conditions, whereas in the presence of aprotic solvent it facilitates partial oxidation of styrene to phenylacetaldehyde and acetophenone.

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.

Organic–Inorganic Hybrid Supermicroporous Iron(III) Phosphonate Nanoparticles as an Efficient Catalyst for the Synthesis of Biofuels

Here we report a novel family of crystalline, supermicroporous iron(III) phosphonate nanomaterials (HFeP-1-3, HFeP-1-2, and HFeP-1-4) with different Fe(III)-to-organophosphonate ligand mole ratios. The materials were synthesized by using a hydrothermal reaction between benzene-1,3,5-triphosphonic acid and iron(III) chloride under acidic conditions (pH ≈ 4.0). Powder X-ray diffraction, N2 sorption, transmission and scanning electron microscopy (TEM and SEM) image analysis, thermogravimetric and differential thermal analysis (TGA-DTA), and FTIR spectroscopic tools were used to characterize the materials. The triclinic crystal phase [P1(2) space group] of the hybrid iron phosphonate was established by a Rietveld refinement of the PXRD analysis of HFeP-1-3 by using the MAUD program. The unit cell parameters are a = 8.749(1), b = 8.578(1), c = 17.725(3) Å; α = 104.47(3), β = 97.64(1), γ = 113.56(3)°; and V = 1013.41 Å(3). With these crystal parameters, we proposed an 24-membered-ring open framework structure for HFeP-1. Compound HFeP-1-3, with an starting Fe/ligand molar ratio of 3.0, shows the highest Brunauer-Emmett-Telller (BET) surface area of 556 m(2) g(-1) and uniform supermicropores of approximately 1.1 nm. The acidic surface of the porous iron(III) phosphonate nanoparticles was used in a highly efficient and recyclable catalytic transesterification reaction for the synthesis of biofuels under mild reaction conditions.

Chromium(VI) grafted mesoporous polyaniline as a reusable heterogeneous catalyst for oxidation reactions in aqueous medium

A new Cr(VI)-grafted mesoporous polyaniline material (Cr-MPANI) has been prepared via simple and facile in situ radical polymerization of aniline followed by reaction with potassium dichromate. This material has been characterized by powder X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), UV-vis diffuse reflectance spectroscopy (DRS) and Thermogravimetric analysis (TGA). Powder XRD and TEM studies suggested the presence of mesophase and disordered wormhole-like mesopores in this sample. Cr-MPANI acts as a very efficient catalyst for the liquid phase oxidation of alkenes, alkanes and aromatic alcohols using 30% H2O2 as oxidant in water. Oxidation reactions were carried out under very mild conditions, and the desired products were obtained with very high selectivity and relatively high yields. Cr-MPANI can be recycled more than five times without an appreciable loss in activity for its respective catalytic reactions.