Surjyakanta Rana

Cesium salts of heteropoly acid immobilized mesoporous silica: An efficient catalyst for acylation of anisole

A series of Cs salt of phosphotungstic acid (Cs-PTA) supported on MCM-41 (Cs-PTA/MCM-41) was synthesized by a wet impregnation method and thoroughly characterized by using various analytical techniques, viz. X-ray diffraction, UV-Vis diffused reflectance spectroscopy (UV-Vis DRS), nitrogen adsorption desorption, scanning electron microscopy (SEM), Infrared spectra (FTIR), temperature programmed reduction (TPR), and temperature programmed desorption (TPD). The spectroscopic results revealed that Cs-PTA is highly dispersed on a MCM-41 surface. The 50 wt.% Cs-PTA supported on MCM-41 showed remarkable catalytic performance toward acylation of anisole reaction. The catalyst is regenerable by simple calcinations without appreciable loss in catalytic activity.

Amine functionalized MCM-41: an efficient heterogeneous recyclable catalyst for the synthesis of quinazoline-2,4(1H,3H)-diones from carbon dioxide and 2-aminobenzonitriles in water

A simple covalently linked amine functionalized MCM-41 compound was investigated using mesoporous catalytic protocols as a highly efficient, heterogeneous and recyclable catalyst for the synthesis of a wide variety of quinazoline-2,4(1H,3H)-dione derivatives from 2-aminobenzonitriles and carbon dioxide in aqueous reaction medium. This catalytic system represents a heterogeneous and environmentally benign protocol. The effect of various reaction parameters, such as the influences of solvent, temperature, CO2 pressure, and time for the synthesis of quinazoline-2,4(1H,3H)-diones were studied. The developed protocol can be applied for the synthesis of the most important key intermediate 6,7-dimethoxyquinazoline-2,4(1H,3H)-dione and several biologically active derivatives such as Prazosin, Bunazosin and Doxazosin. Besides this, the developed catalyst could be reused for five consecutive recycles without any significant loss in its catalytic activity. The amine functionalized MCM-41 catalyst was characterized by various characterization techniques such as FT-IR, TGA/DTA, XRD, Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), and solid state 29Si CP MAS NMR analysis.

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.

A stable amine functionalized montmorillonite supported Cu, Ni catalyst showing synergistic and co-operative effectiveness towards C–S coupling reactions

The objective of this work is to prepare a cheap and highly stable heterogeneous catalyst. This was done by a simple two step approach. The first step involved the preparation of an organic–inorganic hybrid material by covalent grafting of amines on K10 montmorillonite. In the second step the N atoms of the amine groups were co-ordinated to Cu and Ni ions. Both the covalent and co-ordination forces are strong enough to make the catalyst fairly stable during the catalytic runs. The amine functionalization was confirmed by 29Si CP MAS NMR spectroscopy, FTIR spectroscopy and XPS analysis. The XPS analysis revealed Cu and Ni were present in their +2 oxidation states. This bimetallic system was discovered somewhat by curiosity when Ni was added to a previously well-established Cu catalyzed C–S coupling reaction in an attempt to enhance the catalytic activity. When this catalyst was employed in the C–S coupling reaction, it showed wonderful activity with 99% product yield, due to the synergistic effect of the metal duo.

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

Organic amine-functionalized silica-based mesoporous materials: an update of syntheses and catalytic applications

Nowadays, inorganic–organic hybrid materials having pores in the mesoporous range are an intensively studied new category of demanding materials. By template synthesis, the coupling of inorganic and organic components gives pore sizes between 2 and 15 nm with very high surface area. The inorganic–organic hybrid materials were prepared in two ways: one was by co-condensation and the other by post-synthesis method. The inorganic part provides mechanical strength and the organic part shows functional activities. This review gives an overview of the preparation, properties, and potential applications of these materials in the areas of adsorption of pollutant gases like CO2 and heavy metals and in catalysis. Their activity is found to be very impressive in all these fields and it is hoped to be improved in the near future.

A facile synthesis of Cu–Ni bimetallic nanoparticle supported organo functionalized graphene oxide as a catalyst for selective hydrogenation of p-nitrophenol and cinnamaldehyde

We report a facile and environmentally friendly protocol for the synthesis of novel mono-dispersed Cu and Ni bimetallic alloy particles supported on fibrous anime functionalized graphene oxide (GO). In this protocol, we used the organic amine group to increase the binding capacity of supported metal particles. First GO was covalently functionalized by organic amine [N-(2 amino ethyl)-3-amino propyl trimethoxy silane i.e., (AAPTMS)] to form AAPTMS–GO and then metal ions were loaded on the surface of the AAPTMS–GO material. The metal particles supported on AAPTMS functionalized graphene oxide were named as Ni–AAPTMS–GO, Cu–AAPTMS–GO and Cu–Ni–AAPTMS–GO to reflect the metals loaded, and all were fully characterized by various techniques including XRD, SEM, FTIR, Raman spectra, TEM and HRTEM analysis. The 5% loaded with a 1:1 ratio of Cu:Ni of Cu(0)–Ni(0)–AAPTMS–GO showed superb efficiency in conversion of p-nitrophenol to p-aminophenol with 100% conversion and selectivity. Hydrogenation of cinnamaldehyde with the same catalyst gave 85% conversion and 59.8% selectivity towards cinnamal alcohol (COL) at 80 °C. The catalyst also showed good stability in recycling tests.

Ce–Zr/SiO2: a versatile reusable heterogeneous catalyst for three-component synthesis and solvent free oxidation of benzyl alcohol

Ce–Zr loaded on SiO2 as catalyst provides an extremely efficient method to synthesize pyranoquinolines. This catalyst is found to be superb for the three-component synthesis of target compounds and for the solvent-free liquid-phase oxidation of benzyl alcohols. The catalyst is fully recoverable and reusable with no loss of catalytic activity even after multiple cycles.

Multicomponent synthesis of pyridines via diamine functionalized mesoporous ZrO2 domino intramolecular tandem Michael type addition

A new and straightforward synthetic method was developed for the facile synthesis of heterocycle-fused pyridine derivatives in aqueous media from Knoevenagel condensation between an aromatic aldehyde and an active methylene compound. This was followed by Michael type addition of a ketone to the activated double bond of the arylidene via intramolecular cyclization in the presence of diamine functionalized [N-(2 amino ethyl)-3-amino propyl trimethoxy silane (AAPTMS)] mesoporous ZrO2 (AAPTMS/m-ZrO2) to synthesize fused pyridines in high yield. This one-pot conversion, which involves multiple steps and requires no toxic/organic solvents, produced new C–C and C–heteroatom bonds with all reactants efficiently utilized.

Selective oxidation of benzaldehyde by molecular oxygen over molybdovanadophosphoric acid supported MCM-41

A series of molybdovanadophosphoric acid (MVPA) supported on mesoporous silica was synthesized by an incipient wetness impregnation method. The catalysts were characterized by nitrogen adsorption–desorption, X-ray powder diffraction, Fourier-Transform Infra red spectroscopy (FT-IR), UV–Vis Diffused reflectance spectroscopy (UV–Vis DRS), Temperature programmed reduction (TPR) and 31P MAS Nuclear magnetic resonance(NMR) study. The characterization data reveals the incorporation of vanadium in phosphomolybdic acid and retention of intact Keggin ion on the support. The catalytic activities were evaluated for oxidation of benzaldehyde using molecular oxygen as oxidant as the new green reaction system. Among all the promoted catalysts, 50wt% molybdovanadophosphoric acid supported on MCM-41 exhibits highest catalytic activity in oxidation of benzaldehyde, giving 95% conversion. Other oxidants like H2O2 and tert-butyl hydrogen peroxide (TBHP) were also tested for benzaldehyde oxidation reaction.