Synthesis of the first nanomagnetic particles with semicarbazide‐based acidic ionic liquid tag: an efficient catalyst for the synthesis of 3,3′‐(arylmethylene)bis(4‐hydroxycoumarin) and 1‐carbamato‐alkyl‐2‐naphthol derivatives under mild and green conditions

Semicarbazide functionalized with chlorosulfonic acid on the surface of silica‐coated magnetic nanoparticles, {Fe₃O₄@SiO₂@(CH₂)₃Semicarbazide‐SO₃H/HCl}, as a novel magnetic Brønsted acid catalyst according to the aims of green chemistry was synthesized and fully characterized using Fourier transform infrared, UV–visible and energy‐dispersive X‐ray spectroscopies, X‐ray diffraction, scanning electron, transmission electron and atomic force microscopies and thermogravimetric analysis. The capability and excellent activity of this nanoparticle catalyst were exhibited in the synthesis of two series of compounds with important biological activities, namely 3,3′‐(arylmethylene)bis(4‐hydroxycoumarin) and 1‐carbamato‐alkyl‐2‐naphthol derivatives, under mild, green and solvent‐free conditions. To the best of our knowledge, this is the first study of the synthesis and application of {Fe₃O₄@SiO₂@(CH₂)₃Semicarbazide‐SO₃H/HCl} as Brønsted acid solid magnetic nanoparticles. Consequently the present study can open up a novel and promising intuition in the sequence of logical design, synthesis and applications of task‐specific Brønsted acid magnetic nanoparticle catalyst with favourable properties as a full‐fledged efficient material for sustainable approaches. Copyright © 2016 John Wiley & Sons, Ltd.     

The first urea‐based ionic liquid‐stabilized magnetic nanoparticles: an efficient catalyst for the synthesis of bis(indolyl)methanes and pyrano[2,3‐d]pyrimidinone derivatives

Urea‐based ionic liquid stabilized on silica‐coated Fe₃O₄ magnetic nanoparticles, {Fe₃O₄@SiO₂@(CH₂)₃‐Urea‐SO₃H/HCl}, as an unexceptionable and smooth releasing urea fertilizer in alkali soils was synthesized and fully characterized using Fourier transform infrared, UV–visible and energy‐dispersive X‐ray spectroscopies, X‐ray diffraction, scanning and transmission electron microscopies, atomic force microscopy and thermogravimetric analysis. The nanostructure catalyst as a novel, green and efficient catalyst was applied for the synthesis of bis(indolyl)methane derivatives via the condensation reaction between 2‐methylindole and aldehydes at room temperature under solvent‐free conditions. Also, pyrano[2,3‐d]pyrimidinone derivatives were prepared in the presence of the nanomagnetic urea‐based catalyst by the one‐pot three‐component condensation reaction of 1,3‐dimethylbarbituric acid, aldehydes and malononitrile under solvent‐free conditions at 60 °C. To the best of our knowledge, this is the first report of the synthesis of urea‐based ionic liquid stabilized on silica‐coated Fe₃O₄ magnetic nanoparticles. So the present work can open up a new and promising insight in the course of rational design, synthesis and applications of task‐specific fertilizer‐based nanomagnetic ionic liquids with desirable properties as unexceptionable substances for sustainable processes. Copyright © 2016 John Wiley & Sons, Ltd.     

Cu(II) immobilized on guanidinated epibromohydrin‐functionalized γ‐Fe2O3@TiO2 (γ‐Fe2O3@TiO2‐EG‐Cu(II)): A highly efficient magnetically separable heterogeneous nanocatalyst for one‐pot synthesis of highly substituted imidazoles

A simple, efficient and eco‐friendly procedure has been developed using Cu(II) immobilized on guanidinated epibromohydrin‐functionalized γ‐Fe₂O₃@TiO₂ (γ‐Fe₂O₃@TiO₂‐EG‐Cu(II)) for the synthesis of 2,4,5‐trisubstituted and 1,2,4,5‐tetrasubstituted imidazoles, via the condensation reactions of various aldehydes with benzil and ammonium acetate or ammonium acetate and amines, under solvent‐free conditions. High‐resolution transmission electron microscopy analysis of this catalyst clearly affirmed the formation of a γ‐Fe₂O₃ core and a TiO₂ shell, with mean sizes of about 10–20 and 5–10 nm, respectively. These data were in very good agreement with X‐ray crystallographic measurements (13 and 7 nm). Moreover, magnetization measurements revealed that both γ‐Fe₂O₃@TiO₂ and γ‐Fe₂O₃@TiO₂‐EG‐Cu(II) had superparamagnetic behaviour with saturation magnetization of 23.79 and 22.12 emu g^?1, respectively. γ‐Fe₂O₃@TiO₂‐EG‐Cu(II) was found to be a green and highly efficient nanocatalyst, which could be easily handled, recovered and reused several times without significant loss of its activity. The scope of the presented methodology is quite broad; a variety of aldehydes as well as amines have been shown to be viable substrates. A mechanism for the cyclocondensation reaction has also been proposed.     

Au(III) complexes loaded pH‐responsive magnetic nanogels for cancer therapy

A novel pH‐responsive magnetic nanogels were developed with the aim of targeted delivering and simultaneously releasing of newly synthesized Au(III)‐based anticancer drug, Au(1,7‐Phen)Br₃. The obtained nanogels were characterized by FT‐IR, DLS, EDAX, TEM, XRD, ICP‐Ms and MRI. The TEM images showed that the nanogels had a spherical shape with a mean diameter of 20 nm. The in vitro release studies of Au (III)‐loaded nanogels showed a pH‐triggered controlled release of drugs. The in vitro cytotoxicity assay of samples to human cervical cancer HeLa cell lines indicated that the Au(III)‐loaded magnetic nanogels exert higher cytotoxicity in comparison with free Au(III) complex. Fluorescent microscope images indicated that these magnetic nanogels possessed notable cell specific targeting in vitro in the presence of an external magnetic field. The results show that this superparamagnetic nanocarrier is a promising candidate for inhibiting growth of tumor cells.     

Preconcentration and determination of artemisinin in selected Iranian Artemisia species by SPE–LC–MS using poly(N,N′-methylenebisacrylamide) as sorbent material

Journal of the Iranian Chemical Society - Poly(N,N′-methylenebisacrylamide) was synthesized for the selective solid-phase extraction (SPE) and determination of artemisinin in ethanolic...     

Synthesis of Pd@graphene oxide framework nanocatalyst with enhanced activity in Heck-Mizoroki cross-coupling reaction

A new method was developed for producing a catalyst involving a Pd nanoparticle (NP) embedded in a graphene oxide framework (Pd@GOF) with ordered macro- and mesoporous structures. First, 5,5′-diamino-2,2′-bipyridine was selected as cross-linking for covalent modification of GO nanosheets to prepare a three-dimensional (3D) framework with interlayer spaces in which well-dispersed and ultra-small Pd NPs in situ grew and embedded the framework. The synthesized nanopores 3D Pd@GOF can act as nanoreactors to help the reaction substrates thoroughly come into contact with the surface of Pd NPs, thereby exhibiting high activity toward the Heck reaction, rarely reported concerning Pd NPs supported on one-side functionalized graphene. The Pd@GOF catalyst can be used 10 times without any significant loss in the catalytic activity, confirming the long-term stability of this catalyst. Therefore, the covalently assembled GOF was proposed as a universal platform for hosting noble metal NPs to construct the desired metal@GOF nanocatalyst with improved activity and stability that can be used in a broad range of practical applications.     

Highly ordered mesoporous La(III)-substituted 5-oxopyrrolidine-2-carboxylic acid (Glp) immobilized on SBA-15 as a very efficient nanocatalyst for green aerobic oxidative coupling of thiols to disulfides

Selective aerobic oxidative coupling of thiols that are catalyzed by La(III)-substituted 5-oxopyrrolidine-2-carboxylic acid (Glp) immobilized on SBA-15 (SBA-15@Glp–La; SBA = Santa Barbara amorphous) was studied. Using SBA-15@Glp–La, the complete conversion was achieved at room temperature in the presence of air without producing any over-oxidized yields. SBA-15@Glp–La was prepared by post-grafting technique. 5-Oxopyrrolidine-2-carboxylic acid (Glp) condensation followed by La(III) impregnation caused this La(III)-grafted 5-oxopyrrolidine-2-carboxylic acid (Glp) to immobilize on SBA-15. This SBA-15@Glp–La catalyst shows excellent catalytic activity in the selective aerobic oxidative coupling of thiols. Effects of amount of the catalyst, polarity of the solvent, effects of substrate, and catalyst reusability were investigated. It has been observed that seven repetitive reaction cycles did not cause any appreciable loss in the catalytic activity of this catalyst. The catalyst characterization by scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction, Fourier-transform infrared spectroscopy, thermal gravimetric analysis, transmission electron microscopy, inductively coupled plasma, elemental mapping, and N₂ adsorption–desorption is reported. The procedure developed is heterogeneous and environmentally benign.     

The destabilization of hydrogen bonds in an external E-field for improved switch performance

The effect of an electric field on a recently proposed molecular switch based on a quinone analogue was investigated using next-generation quantum theory of atoms in molecules (QTAIM) methodology. The reversal of a homogenous external electric field was demonstrated to improve the “OFF” functioning of the switch. This was achieved by destabilization of the H atom participating in the tautomerization process along the hydrogen bond that defines the switch. The “ON” functioning of the switch, from the position of the tautomerization barrier, is also improved by the reversal of the homogenous external electric field: this result was previously inaccessible. The “ON” and “OFF” functioning of the switch was visualized in terms of the response of the most preferred directions of motion of the electronic charge density to the applied external field. All measures from QTAIM and the stress tensor provide consistent results for the factors affecting the “ON” and “OFF” switch performance. Our analysis therefore demonstrates use for future design of molecular electronic devices. © 2019 Wiley Periodicals, Inc.     

Development of a ZHER3‐Affibody‐Targeted Nano‐Vector for Gene Delivery to HER3‐Overexpressed Breast Cancer Cells

Despite the initial successes of gene delivery applications, they faced on several intrinsic drawbacks including toxicity and immunogenicity. Therefore, alternative gene‐delivery systems derived from recombinant peptides have emerged and is rapidly developing. Human epidermal growth factor receptor‐3 (HER3) shows high activity in tumor resistance to anti‐human epidermal growth factor receptor 2 (HER2) therapies. In this study, an affibody molecule against HER3 is conjugated to a biomimetic peptide RALA (an amphipathic and cationic peptide enriched with arginine) and the ability of the fusion vector for targeting HER3 and afterward delivering specific genes in breast cancer cells is evaluated. The results demonstrate that the biopolymeric platform, which contains an affibody‐conjugated RALA peptide, can effectively condense DNA into nanoparticles and target the overexpressed HER3 receptors in breast cancer cells and transfer specific genes. The use of such a recombinant biopolymer may pave the way for the development of sensitive and effective diagnostic and treatment tool for breast cancer.     

Evidence of structural strain in epitaxial graphene layers on 6H-SiC(0001)

The early stages of epitaxial graphene layer growth on the Si-terminated 6H-SiC (0001) are investigated by Auger electron spectroscopy (AES) and depolarized Raman spectroscopy. The selection of the depolarized component of the scattered light results in a significant increase in the C-C bond signal over the second order SiC Raman signal, which allows us to resolve submonolayer growth, including individual, localized C=C dimers in a diamondlike carbon matrix for AES C/Si ratio of approximately 3, and a strained graphene layer with delocalized electrons and Dirac single-band dispersion for AES C/Si ratio >6. The linear strain, measured at room temperature, is found to be compressive, which can be attributed to the large difference between the coefficients of thermal expansion of graphene and SiC. The magnitude of the compressive strain can be varied by adjusting the growth time at fixed annealing temperature.