Starch nanoparticles as a bio-nanocatalyst in synthesis of diheteroaryl thioethers

Nanostarch is shown to be a highly efficient, eco-friendly and heterogenous organocatalyst for the synthesis of the diheteroaryl thioethers via one-pot reaction of methylcarbonyls, thiourea and iodine in DMSO. This method offers significant advantages such as available starting materials, higher purity and excellent yield of products, very easy reaction conditions and absence of any tedious purification. Furthermore, because of employing eco-friendly catalyst without using transition metal catalysts, this novel method emerges as a green-approach leading to less harmful residues. Moreover, a mechanism was proposed to rationalize the reaction and the role of starch nanoparticles was also investigated in these transformations.     

A highly efficient magnetic solid acid catalyst for synthesis of 2,4,5-trisubstituted imidazoles under ultrasound irradiation

Fe₃O₄ nanoparticles were prepared by chemical coprecipitation method and subsequently coated with 3-aminopropyltriethoxysilane (APTES) via silanization reaction. Grafting of chlorosulfuric acid on the amino-functionalized Fe₃O₄ nanoparticles afforded sulfamic acid-functionalized magnetic nanoparticles (SA-MNPs). SA-MNPs was found to be a mild and effective solid acid catalyst for the efficient, one-pot, three-component synthesis of 2,4,5-trisubstituted imidazoles under ultrasound irradiation. This protocol afforded corresponding imidazoles in shorter reaction durations, and in high yields. This green procedure has many obvious advantages compared to those reported in the previous literatures, including avoiding the use of harmful catalysts, easy and quick isolation of the products, excellent yields, short routine, and simplicity of the methodology.     

TiO2 nanoparticles supported on the Fe3O4@SiO2 nanocomposites: a novel magnetic nanocatalyst for the synthesis of 2-aminothiazoles

Journal of Nanoparticle Research - Nano TiO2 supported on the Fe3O4@SiO2 nanocomposites is introduced as a novel catalyst for the environmental synthesis of 2-aminothiazoles in PEG-200 as a green...     

Synthesis of new TCH/Ni‐based nanocomposite supported on SBA‐15 and its catalytic application for preparation of benzimidazole and perimidine derivatives

A stable nickel‐decorated SBA‐15 nanocomposite (Ni/TCH@SBA‐15) was synthesized through surface modification of silica nanoparticles with 3‐chloropropyltriethoxysilane (CPTES) and thiocarbohydrazide (TCH) followed by metal–ligand coordination with Ni (II). The structure of this organometallic nanocomposite was characterized by Fourier transform‐infrared, field emission‐scanning electron microscopy, EDAX, transmission electron microscopy, atomic absorption spectroscopy and N₂ adsorption–desorption (Brunauer–Emmett–Teller) techniques. The catalytic performance of Ni/TCH@SBA‐15 (NNTS‐15) was determined for the synthesis of 2‐aryl‐substituted benzimidazoles and 2,3‐dihydroperimidines. The excellent yields within shorter reaction times, simplicity of catalytic methods, non‐toxicity and clean reactions, mild reaction conditions and easy work‐up procedure are the important merits of these synthetic protocols. Moreover, the Ni (II) bonded to the SBA‐15 surface was stable under the catalytic reaction conditions resulting in its efficient recycling and reuse.     

Mesoporous nanocrystalline MgAl2O4: A new heterogeneous catalyst for the synthesis of 2,4,6-triarylpyridines under solvent-free conditions

In this paper, one-pot synthesis of 2,4,6-triarylpyridine by condensation of subsisted acetophenone (II), aromatic aldehydes (I), and ammonium acetate (III) in the presence of nanocrystalline MgAl₂O₄ as a new heterogeneous catalyst under solvent-free conditions is reported. Advantages of this method are the use of spatially-hindered aldehydes such as 2-methoxy-, 2-fluoro-, and 2-chlorobenzaldehydes, a new nanocatalyst with high surface area, shorter reaction time, easier workup, higher yield, and its environmental friendliness. The performance of this reaction under solvent free conditions using heterogeneous catalysts like MgAl₂O₄ could enhance its efficiency from an economic as well as green chemistry point of view.     

Immobilized ionic liquid on superparamagnetic nanoparticles as an effective catalyst for the synthesis of tetrasubstituted imidazoles under solvent-free conditions and microwave irradiation

The ionic liquid 1-methyl-3-(3-trimethoxysilylpropyl) imidazolium chloride was immobilized on superparamagnetic Fe₃O₄ nanoparticles (IL-MNPs) and used as an efficient heterogeneous catalyst for the one-pot synthesis of 1,2,4,5-tetrasubstituted imidazoles under solvent-free conditions using microwave irradiation. The reactions in conventional heating conditions were compared with the microwave-assisted reactions. The combined merits of microwave irradiation and immobilized ionic liquid on superparamagnetic nanoparticles make the four-component condensation with safe operation, low pollution, and rapid access to products and simple work-up.     

Encapsulation of nanoparticles using linear–dendritic macromolecules

Benzyl alcohol and Rose Bengal were loaded and entrapped using linear–dendritic macromolecules by two procedures. In the first procedure, benzyl alcohol was attached to the end functional groups of linear–dendritic macromolecules by ester bonds to afford linear–dendritic–host conjugates. In the second procedure, entrapment was based on physical interactions between Rose Bengal and linear–dendritic macromolecules; this procedure is known as complexation method. Loading and binding capacity of different linear–dendritic macromolecules was investigated using ¹H nuclear magnetic resonance (NMR) and UV spectroscopy methods. It was found the loading or binding capacity of linear–dendritic macromolecules depends on their generation, so that higher generations have higher loading or binding capacity. Diameter of nanocarriers was investigated using dynamic light scattering (DLS) experiments, and it was between 16 and 50 nm for different nanocarriers. Release of guest molecules from nanocarriers was evaluated at pH 1, 7.4, and 10. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.