Md. Asif Iqubal

Mesoporous poly-melamine-formaldehyde stabilized palladium nanoparticle (Pd@mPMF) catalyzed mono and double carbonylation of aryl halides with amines

A new mesoporous poly-melamine-formaldehyde material supported Pd nano catalyst (mPMF–Pd0) has been synthesized and characterized by thermogravimetric analysis (TGA), powder X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectrometry (EDS), high-resolution transmission electron microscopy (HRTEM), UV-vis diffuse reflection spectroscopy (DRS), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS) and a N2 adsorption study. The mPMF–Pd0 material showed very good catalytic activity in the field of mono and double amino carbonylation of aryl bromides/iodides. Moreover, the catalyst is easily recoverable and can be reused six times without appreciable loss of catalytic activity in the above reactions. So, the highly dispersed and strongly bound palladium(0) sites in the mPMF–Pd0 could be responsible for the observed high activities. Due to strong binding with the functional groups of the polymer, no evidence of leached Pd from the catalyst during the course of reaction occurred, suggesting true heterogeneity in the catalytic process.

Silver nanoparticles embedded over porous metal organic frameworks for carbon dioxide fixation via carboxylation of terminal alkynes at ambient pressure.

Ag nanoparticles (NPs) has been supported over a porous Co(II)-salicylate metal-organic framework to yield a new nanocatalyst AgNPs/Co-MOF and it has been thoroughly characterized by powder X-ray diffraction (XRD), thermogravimetric analysis (TGA), energy dispersive X-ray spectrometry (EDX), high-resolution transmission electron microscopy (HR-TEM), UV-vis diffuse reflection spectroscopy (DRS) and N2 adsorption/desorption analysis. The AgNPs/Co-MOF material showed high catalytic activity in the carboxylation of terminal alkynes via CO2 fixation reaction to yield alkynyl carboxylic acids under very mild conditions. Due to the presence of highly reactive AgNPs bound at the porous MOF framework the reaction proceeded smoothly at 1atm CO2 pressure. Moreover, the catalyst is very convenient to handle and it can be reused for several reaction cycles without appreciable loss of catalytic activity in this CO2 fixation reaction, which suggested a promising future of AgNPs/Co-MOF nanocatalyst.

A route for direct transformation of aryl halides to benzyl alcohols via carbon dioxide fixation reaction catalyzed by a (Pd@N-GMC) palladium nanoparticle encapsulated nitrogen doped mesoporous carbon material

A nitrogen doped mesoporous carbon material was synthesized from glucose and melamine under hydrothermal treatment. A soft template, Brij-35 was used as a template. A nitrogen containing high surface area and porous channels makes this material an important support for palladium nanoparticles as well as a carbon dioxide capturing agent. Ethylene glycol was used as a reducing agent for the palladium nanoparticle synthesis. The palladium nanoparticle embedded porous nitrogen doped carbon material (Pd@N-GMC) was used for the synthesis of benzyl alcohols from aryl iodides via carbon dioxide fixation reaction. The catalyst was highly stable and reusable without any significance loss of its activity.

Direct oxidative esterification of alcohols and hydration of nitriles catalyzed by a reusable silver nanoparticle grafted onto mesoporous polymelamine formaldehyde (AgNPs@mPMF)

A nitrogen-rich mesoporous organic polymer was synthesized as a novel support. A silver nanoparticle was synthesized and grafted onto it. The prepared catalyst (AgNPs@mPMF) was characterized by powder X-ray diffraction (XRD), scanning electron microscopy(SEM) and energy dispersive X-ray spectrometry (EDS), thermogravimetric analysis (TGA), high-resolution transmission electron microscopy (HRTEM), UV-vis diffuse reflectance spectroscopy (DRS), N2 adsorption, Raman spectroscopy and EPR study. The catalytic activity was evaluated for the oxidative esterification reaction of alcohols and hydration of nitriles. The oxidative esterification reaction was carried out for various activated alcohols giving excellent yields of the corresponding ester products. The catalyst was also efficient in the hydration of nitriles. Both reactions were optimized by varying the bases, temperatures and solvents. The catalyst can be facilely recovered and reused six times without a significant decrease in its activity and selectivity.

A mesoporous organosilica grafted Pd catalyst (MOG-Pd) for efficient base free and phosphine free synthesis of tertiary butyl esters via tertiary-butoxycarbonylation of boronic acid derivatives without using carbon monoxide

A mesoporous organosilica grafted palladium(II) catalyst was synthesized and characterized using various spectroscopic techniques. Its catalytic activity was evaluated for the synthesis of tertiary butyl esters via tert-butoxycarbonylation of boronic acid derivatives. The tertiary butyl esters were obtained directly from boronic acid pinacol esters and di-tert-butyl dicarbonate. The reaction was optimized by varying the bases, temperatures and solvents. The catalyst was very stable and could be facilely recovered and reused six times with no significant decrease in its activity and selectivity.

Thermal Condensation of Glycine and Alanine on Metal Ferrite Surface: Primitive Peptide Bond Formation Scenario

The amino acid condensation reaction on a heterogeneous mineral surface has been regarded as one of the important pathways for peptide bond formation. Keeping this in view, we have studied the oligomerization of the simple amino acids, glycine and alanine, on nickel ferrite (NiFe2O4), cobalt ferrite (CoFe2O4), copper ferrite (CuFe2O4), zinc ferrite (ZnFe2O4), and manganese ferrite (MnFe2O4) nanoparticles surfaces, in the temperature range from 50–120 °C for 1–35 days, without applying any wetting/drying cycles. Among the metal ferrites tested for their catalytic activity, NiFe2O4 produced the highest yield of products by oligomerizing glycine to the trimer level and alanine to the dimer level, whereas MnFe2O4 was the least efficient catalyst, producing the lowest yield of products, as well as shorter oligomers of amino acids under the same set of experimental conditions. It produced primarily diketopiperazine (Ala) with a trace amount of alanine dimer from alanine condensation, while glycine was oligomerized to the dimer level. The trend in product formation is in accordance with the surface area of the minerals used. A temperature as low as 50 °C can even favor peptide bond formation in the present study, which is important in the sense that the condensation process is highly feasible without any sort of localized heat that may originate from volcanoes or hydrothermal vents. However, at a high temperature of 120 °C, anhydrides of glycine and alanine formation are favored, while the optimum temperature for the highest yield of product formation was found to be 90 °C.

Surface interaction of ribonucleic acid constituents with spinel ferrite nanoparticles: a prebiotic chemistry experiment

The understanding of the interaction between nucleic acid components and mineral surface is of significant importance in respect to chemical evolution and the origin of life issue. Spinel ferrites are compounds with high magnetic properties and are found in the Earth’s crust, upper mantle and meteorites. Trevorite is a well-known spinel metal ferrite (NiFe2O4) found in Orgueil meteorite, Soltmany meteorite and also recently discovered in Khatyrka meteorite. No studies seem to have been done using such compounds in respect of chemical evolution. Herein the results of work on the interaction of ribonucleic acid constituents, 5′-CMP, 5′-UMP, 5′-GMP and 5′-AMP, with spinel ferrite nanoparticles (NiFe2O4, CoFe2O4, CuFe2O4, and MnFe2O4) in the concentration range of 1.0 × 10−4 M to 4.0 × 10−4 M at three different pHs (4.0, 7.0 and 9.0) have been reported. The maximum percent binding was found at pH 4.0 for all the ribonucleotides studied. Nickel ferrite (NiFe2O4) showed a higher percent binding (82–97%) while manganese ferrite (MnFe2O4) exhibited the lowest (34–67%) adsorption affinity for all ribonucleotides. Experimental results showed the participation of different functional groups (amine, phosphate and carbonyl) of nucleotides in the binding process, which is in good agreement with previous mineral–nucleotide interaction studies. The adsorption capacity of ribonucleotides on spinel ferrites was found to be higher as compared to some previously studied metal oxides such as zinc oxide (ZnO), manganese oxides (MnO, Mn2O3, Mn3O4 and MnO2), and acidic, neutral and basic alumina.

Silica Functionalized Magnetic Nickel Ferrite Nanoparticles as an Efficient Recyclable Catalyst for S-Arylation in Aqueous Medium

Silica coated NiFe2O4 NPs has been synthesized. It has been characterized by XRD, TEM, SEM-EDX and FT-IR. The catalytic activity of the Silica coated NiFe2O4 NPs has been tested for the S-arylation reaction in water with high yield. In this reaction water was used as the green solvent. The effects of solvents, reaction time and catalyst amount for the reaction was reported. This catalyst showed excellent catalytic activity and recyclability. The Silica coated NiFe2O4 NPs catalyst could be easily recovered by filtration and reused more than five times without appreciable loss of its initial activity.