Synthesis and characterization of a green and recyclable arginine-based palladium/CoFe2O4 nanomagnetic catalyst for efficient cyanation of aryl halides.

The utilization of magnetic nanoparticles in the fields of science and technology has gained considerable popularity. Among their various applications, magnetic nanoparticles have been predominantly employed in catalytic processes due to their easy accessibility, recoverability, effective surface properties, thermal stability, and low cost. In this particular study, cyanuric chloride and arginine were utilized to synthesize an arginine-based oligomeric compound (ACT), which was supported on cobalt ferrite, resulting in a green catalyst with high activity and convenient recyclability for the cyanation reaction of aryl halides. The Pd/CoFe2O4@ACT nanomagnetic catalyst demonstrated excellent performance in the cyanation of various aryl iodides and bromides, yielding favorable reaction outcomes at a temperature of 90 °C within a duration of 3 hours. The synthesized nanoparticles were successfully characterized using various techniques, including FTIR, FE-SEM, EDX/MAP, XRD, TEM, TGA, BET, and ICP-OES. Moreover, the Pd/CoFe2O4@ACT catalyst exhibited remarkable catalytic activity, maintaining an 88% performance even after five consecutive runs. Analysis of the reused catalyst through SEM and TEM imaging confirmed that there were no significant changes in the morphology or dispersion of the particles. Ultimately, it was demonstrated that the Pd/CoFe2O4@ACT nanomagnetic catalyst outperformed numerous catalysts previously reported in the literature for the cyanation of aryl halides.

Modified nano magnetic Fe2O3-MgO as a high active multifunctional heterogeneous catalyst for environmentally beneficial carbon-carbon synthesis.

In this study, novel nanomagnetic catalysts, namely Fe2O3-MgO@choline formate (Ch. F.) and Fe2O3-MgO@choline cyanide (Ch. CN), were synthesized through immobilizing choline-based ion liquids to magnetic support via a simple and cost-effective methodology. FT-IR, TGA, FE-SEM, VSM, EDS, BET, and XRD techniques were employed to assess and characterize these organic-inorganic compounds. Following the successful preparation of nanoparticles, the catalysts were utilized in Knoevenagel and benzoin condensations. Fe2O3-MgO@Ch.F. exhibited exceptional activity in Knoevenagel condensation under solvent-free conditions at room temperature, achieving high yields (91-98%) in a short timeframe. Similarly, Fe2O3-MgO@Ch.CN demonstrated remarkable activity in benzoin condensation under environmentally friendly solvent conditions, yielding higher isolated yields (76-88%). Furthermore, these magnetically recyclable multifunctional catalysts displayed the ability to be reused up to five times without a significant loss in efficiency. Additionally, the heterogeneity of this nanocatalyst was investigated using the hot filtration technique. The findings indicated that the reaction primarily occurs via a heterogeneous pathway.

Fe3O4@SiO2@NiAl-LDH microspheres implication in separation, kinetic and structural properties of phenylalanine dehydrogenase.

Fe3O4@SiO2@NiAl-LDH three-components microsphere contains a Fe3O4@SiO2 magnetic core and a layered double hydroxide with nickel cation provide the binding ability to (His)-tagged-protein and exhibits high performance in protein separation and purification. The morphology and chemistry of the synthesized Fe3O4@SiO2@NiAl-LDH microspheres were characterized by energy-dispersive X-ray spectroscopy (EDX), scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared (FTIR), vibrating sample magnetometer (VSM), Dynamic light scattering (DLS). Purified enzyme was assesed with SDS-PAGE (sodium dodecyl sulfate-polyacrylamide gel electrophoresis and intrinsic fluorescence spectroscopy. In this study, the separation of phenylalanine dehydrogenase (PheDH) by Fe3O4@SiO2@NiAl -LDH was performed and the effect of microsphere was investigated on the kinetic and structural properties of PheDH. After purification, kinetic parameters such as Km, Vmax, Kcat, kcat/Km, optimum temperature, thermal stability, and and activation energy were evaluated and compared according to the mentioned methods. The interaction between the enzyme and the microsphere displayed a high performance in protein binding capacity. The results also revealed that the kinetic parameters of the enzyme changed in a dose-dependent manner in the presence of a microsphere. Moreover, the results of intrinsic fluorescence and Circular Dichroism (CD) confirmed the structural changes of the protein in the interaction with the microsphere.

Magnetically separable triazine-based Cu(ii)-vitamin B5 complex in nitromethane toward efficient heterogeneous cyanation reaction of aryl halides.

In the current study, a highly efficient heterogeneous copper catalyst has been developed by supporting copper acetate on a magnetically separable triazine-vitamin B5 system. After the successful characterization of the prepared nanoparticles by various techniques such as FT-IR, FE-SEM, EDX/MAP, XRD, TEM, TGA, VSM, and ICP-OES, the catalytic efficiency of them were evaluated in the cyanation reaction of aryl halides in the presence of nitromethane as a non-toxic and cost-effective cyanation source. The cyanation products were obtained in desirable yields. Notably, the magnetic nanocatalyst can be easily recovered and reused at least five times without a significant decrease in its performance.

Selective Oxidation of Alcohols through Fe3 O4 @SiO2 /K2 CO3 -Glycerin Deep Eutectic Solvent as a Heterogeneous Catalytic System.

K2 CO3 /Glycerin as a deep eutectic solvent (DES) was anchored covalently onto functionalized magnetic nanoparticles and showed a significant activity towards the oxidation of various alcohols under mild conditions with a short reaction time and good to high yield. A combination of the magnetic nanoparticles and deep eutectic solvent offers a novel, green, reusable catalyst with easy separation. Also, the catalyst structure was well characterized using techniques such as FT-IR spectroscopy, XRD, SEM, TGA, BET, VSM, TEM, and energy-dispersive X-ray spectroscopy (EDS).

Photocatalytic aerobic oxidative functionalization (PAOF) reaction of benzyl alcohols by GO-MIL-100(Fe) composite in glycerol/K2CO3 deep eutectic solvent.

An MIL-100 (Fe)/graphene oxide (GO) hybrid, a fairly-known composite, was made through a simple one-step procedure and played a highlighted role in the photo-induced oxidative functionalization of the benzylic C-H bond. To identify the given binary composite, various techniques were applied: FT-IR, P-XRD, SEM, nitrogen absorption-desorption analysis, TGA, TEM, and UV-Visible DRS spectra. Proportions of GO used within the structure of the prepared composite differently ranged from low to high amount, and the most optimized ratio met at 38.5% of GO as the most efficient catalyst. Additionally, the reaction ran in Glycerol/K2CO3 (2:1) as the optimal solvent. The elemental roles of O2·- and OH- were supposed to be the major ones for running a tandem oxidation-Knoevenagel reaction. The heterogeneity and reusability of the catalyst were also examined and confirmed after five successive runs.

Innovative application of magnetically modified bovine horn as a natural keratin resource in the role of value-added organocatalyst.

This study presents the conversion of bovine horn powder (BHP) as an available and low-cost waste material to a value-added highly recyclable catalyst. This green catalyst was prepared through the immobilization of BHP, as a natural keratin resource, on the magnetic Fe3O4 nanoparticles. The successful preparation of the catalyst was fully investigated using Fourier transform infrared, X-ray diffraction, and energy-dispersive X-ray spectroscopies as well as field emission scanning electron microscopy, vibrating sample magnetometry, and thermogravimetry. The catalytic efficiency of the prepared magnetic organocatalyst was evaluated in the synthesis of a large series of amide derivatives through the solvent-free transamidation reaction of different amides and amines with yields of 75-96%.

Confined-based catalyst investigation through the comparative functionalization and defunctionalization of Zr-MOF.

In metal-organic frameworks, confined space as a chemical nanoreactor is as important as organocatalysis or coordinatively unsaturated metal site catalysis. In the present study, a set of mixed-ligand structures with UiO-66 architecture have been prepared. To the best of our knowledge, for the first time, structures derived by the solvothermal mixing ligand method and ultrasonic-assisted linker exchange approaches have been compared. Additionally, the relationship between the preparation method, structural properties, and catalytic efficiency of the prepared materials in the Knoevenagel condensation of aldehydes has been investigated. The prepared catalyst is very stable and can be recovered and reused for at least ten periods.

Spatial distribution of regional infrastructures in the northeast of Iran using GIS and Mic Mac observation (A case of Khorasan Razavi province).

Nowadays, recognizing the current situation and forecasting the desired status of spatial analysis of infrastructures regarding security and defense considerations is of great importance. Besides, the use of approaches such as futures studies and its simultaneous application with GIS has the most fundamental contribution to the field of decision-making and appropriate planning method in studies on the spatial defense planning. Accordingly, this paper aims to evaluate the spatial distribution of regional infrastructures in the northeast of Iran using a passive defense approach. In this regard, a descriptive-analytical research methodology, library-documentary studies, and statistical surveys were used in the model framework along with software (Mic Mac and Scenario Wizard) and system analysis (GIS) to achieve the research objective. The statistical population of the study was defined in two human and spatial scales. The entire geographical space of Khorasan Razavi province made the spatial scale. On the human scale, 40 experts (n = 15) and elites (n = 25) in the field of this study were selected as the statistical sample using a purposive non-random model. It is noteworthy that all of the subjects had the required scientific and executive knowledge. According to the total research indicators, the vulnerable zones of the study area could be distinguished into five categories of areas with very high (7.33%), high (16.52%), moderate (29.78%), low (16.94%), and very low (29.4%) vulnerability. Also, according to the results, the density and dispersion patterns of the study area infrastructures were concentrated, clustered, and randomly self-clustered, respectively. In the meantime, factors such as legal, policy, and institutional infrastructure criteria were identified as key drivers influencing the spatial distribution of the province infrastructures. Therefore, it is possible to realize the future models in three scenarios of high desirability (green status), acceptable (yellow status), and crisis (red status). Finally, the paper concludes with some suggestions to increase the desirability of infrastructures in Khorasan Razavi province.

The synthesis and characterization of Fe2O3@SiO2-SO3H nanofibers as a novel magnetic core-shell catalyst for formamidine and formamide synthesis.

Over the past several decades, the fabrication of novel ceramic nanofibers applicable in different areas has been a frequent focus of scientists around the world. Aiming to introduce novel ceramic core-shell nanofibers as a magnetic solid acid catalyst, Fe2O3@SiO2-SO3H magnetic nanofibers were prepared in this study using a modification of Fe2O3@SiO2 core-shell nanofibers with chlorosulfonic acid to increase the acidic properties of these ceramic nanofibers. The products were characterized by scanning electron microscope (SEM), transmission electron microscope (TEM), energy dispersive X-ray spectroscope (EDS), vibrating sample magnetometer (VSM), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR). The prepared nanofibers were used as catalysts in formamide and formamidine synthesis. The treatment of aqueous formic acid using diverse amines with a catalytic amount of Fe2O3@SiO2-SO3H nanofibers as a reusable, magnetic and heterogeneous catalyst produced high yields of corresponding formamides at room temperature. Likewise, the reaction of diverse amines with triethyl orthoformate led to the synthesis of formamidine derivatives in excellent yields using this novel catalyst. The catalytic system was able to be recovered and reused at least five times without any catalytic activity loss. Thus, novel core-shell nanofibers can act as efficient solid acid catalysts in different organic reactions capable of being reused several times due to their easy separation by applying magnet.

N-Heterocyclic carbene (NHC)-catalyzed oxidative [3+2] annulation of dioxindoles and enals: mechanism, role of NHC, role of a mixture of bases with different strength, and origin of stereoselectivity.

Over recent years, in-depth understanding of the mechanism of oxidative N-heterocyclic carbene (NHC) catalyzed reactions in the presence of a mild oxidant and the structure of key radical intermediates have been considered as an important challenge in organic chemistry. Furthermore, the role of using a mixture of bases with different strengths is unclear in NHC-catalyzed reactions. In this paper, the detailed competing oxidative mechanisms, origin of stereoselectivity, and role of the NHC-organocatalyst in the NHC-catalyzed reactions of dioxindoles with enals were studied using the density functional theory method. In addition, the roles of newly produced Brønsted acids of the applied bases, i.e.DBU·H+ and DABCO·H+, are examined. The computational results indicated that the oxidation of the Breslow intermediate by nitrobenzene (NB) occurs first through a hydrogen atom transfer (HAT) pathway from the Breslow intermediate, and then it is oxidized into acyl azolium by single electron transfer (SET). We found that the energy barrier of the proton transfer processes is remarkably reduced by the conjugated Brønsted acid of the weaker base in the solution. Further, the calculated results revealed that the NHC catalyst has different behavior before and after the oxidation of the Breslow intermediate in these reactions. Before oxidation, the nucleophilicity of R1 increased by adding R1 to NHC, while, after the oxidation process, the electrophilicity of R1 increases, and as a result the product of oxidation, α, ß unsaturated acyl azolium, acts as an electrophile. This mechanistic study paves the way for the rational design of oxidative NHC-catalyzed reactions.

Ultrasonic Synthesis and Characterization of 2D and 3D Metal-Organic Frameworks and Their Application in the Oxidative Amidation Reaction.

Ultrasound irradiation as an environmentally friendly and inexpensive method successfully applied for the synthesis of two-dimensional (2D) and three-dimensional (3D) metal-organic frameworks (MOFs). Sonochemically synthesized AM-Co1 and AM-Co2 powder has been employed as a green heterogeneous catalyst for the oxidative amidation reaction. The results show that AM-Co1 with a two-dimensional (2D) structure can act as an excellent catalyst for this reaction under ultrasonic irradiation compared to AM-Co2 with a three-dimensional (3D) structure. According to green principles, we used water as a green solvent and air as an oxidant for the oxidative amidation reaction. A wide variety of aldehydes and amines have been used for the synthesis of amides in good to excellent yields (75-90%). Also, the MOF catalyst could be recovered and reused several times without loss of activity.

Stabilizing Pd on magnetic phosphine-functionalized cellulose: DFT study and catalytic performance under deep eutectic solvent assisted conditions.

A highly efficient metal-based nanocatalyst was developed by stabilization of palladium nanoparticles on magnetically retrievable phosphine-functionalized cellulose (Fe3O4@PFC-Pd(0)). The synthesized nanocatalyst was characterized by various techniques such as FT-IR, XRD, FE-SEM, TEM, EDX, UV-vis, ICP, TGA, BET and VSM. Moreover, to investigate the metal-ligand interactions present in the nanocatalyst, covalent and electrostatic interactions, density functional theory (DFT) and quantum theory of atoms in molecule (QTAIM) methods were employed. The catalytic efficacy of the nanoparticles was evaluated in Sonogashira and Suzuki coupling reactions in basic deep eutectic mixture, as a sustainable solvent. Due to the cooperative interactions of primary hydroxyl group of cellulose, phosphorus atom and phenyl ring of phosphine moiety with Pd atom, the nanocatalyst exhibits high activity and stability. The nanocatalyst can be easily recycled and reused at least five times without an appreciable loss of activity. Also, the other merits including short reaction times, short synthetic route to prepare catalyst, trace metal leaching to the reaction medium, cost-effective and eco-friendly conditions can be mentioned for the present approach.

Modulation of the competition between renaturation and aggregation of lysozyme by additive mixtures.

The effects of 17 kinds of additive mixtures have been studied on refolding and aggregation of a model protein, lysozyme. Most of the prepared mixtures were efficient in inhibiting aggregation of the protein, and, surprisingly, four novel additive mixtures, i.e., lactic acid: l-arginine, lactic acid: l-glutamine, choline chloride: lactic acid, and imidazolium salt: ß-cyclodextrin as well as choline chloride: urea exhibited a more remarkable efficacy in suppressing aggregation. Among these, lactic acid: l-arginine was identified as the most efficient additive, and lactic acid: l-glutamine and choline chloride: lactic acid were inefficient to recover the enzyme activity. In contrast, choline chloride: ethylene glycol: imidazole, choline chloride: glycerol: imidazole, imidazole: betaine: ethylene glycol were found to be less effective mixtures in preventing enzyme aggregation. Totally, it was demonstrated that the protective effects of the mixtures were improved as their concentrations increased. The improvement was more remarkable for imidazolium salt: ß-cyclodextrin and choline chloride: urea, where the denatured lysozyme was reactivated and recovered up to 85% of its initial activity by enhancing their concentrations from 1 to 5% (V/V). It is suggested that such solution additives may be further employed as artificial chaperones to assist protein folding and stability.

Activity, stability and structure of laccase in betaine based natural deep eutectic solvents.

Natural deep eutectic solvents (NADES) play a role as alternative media to water in living organisms. They are formed by mixing two or more natural compounds in certain ratios producing a liquid having a lower melting point than those of the individual NADES components. Although, the eutectics medium bring several advantages as enhanced solubility of non-polar substrates and/or products, however, these advantages would often be limited by a lower stability of biocatalysts in these systems. To examine this matter, biochemical characterization, thermal stability and tertiary structure of laccase from Bacillus HR03 was investigated as a model in betaine and choline based NADES. In eutectics containing choline, a sudden drop in enzyme activity and stability was observed. Betaine based eutectics exhibited a better media for the laccase stability in comparison with the aqueous buffer and choline chloride eutectics. The enzyme highest activity was observed in 20% (v/v) glycerol:betaine (2:1). Among betaine based eutectics, the enzyme exhibited its highest stability in sorbitol:betaine:water (1:1:1) and glycerol:betaine (2:1) compared to the aqueous buffer at 80 and 90°C. Associated conformational changes caused by solvents were monitored using fluorescence technique. Finally, the effects of NADES on the enzyme activity and stability were discussed.

Superparamagnetic Fe(OH)3@Fe3O4 Nanoparticles: An Efficient and Recoverable Catalyst for Tandem Oxidative Amidation of Alcohols with Amine Hydrochloride Salts.

Magnetic Fe(OH)3@Fe3O4 nanoparticles were successfully prepared and characterized. This magnetic nanocomposite was employed as an efficient, reusable, and environmentally benign heterogeneous catalyst for the direct amidation of alcohols with amine hydrochloride salts. Several derivatives of primary, secondary and tertiary amides were synthesized in moderate to good yields in the presence of this catalytic system. The catalyst was successfully recycled and reused up to six times without significant loss of its catalytic activity.

Modifying effect of imidazolium-based ionic liquids on surface activity and self-assembled nanostructures of sodium dodecyl sulfate.

The effect of four cationic ionic liquids (ILs), 1-butyl-3-methylimidazolium chloride (BMImCl), 1-butyl-3-methylimidazolium bromide (BMImBr), 1-hexyl-3-methylimidazolium chloride (HMImCl), and 1-hexyl-3-methyl-imidazolium bromide (HMImBr) on surface activity and micellization of an anionic surfactant, sodium dodecyl sulfate (SDS), is studied. The thermodynamic data on micellization and surface adsorption are obtained from tensiometry and conductometry. The applicability of UV-visible spectroscopy to study of SDS/IL systems is also investigated using Crystal Violet as the probe. Cyclic voltammetry, dynamic light scattering, and TEM imaging are employed to investigate the size and morphology of aggregates. According to the findings, addition of butyl-chained ILs to aqueous SDS results in only a slight gradual increase in average aggregate size whereas the size of SDS assemblies are dramatically increased upon addition of hexyl-chained ILs. It is proposed that BMIm(+) cations of the IL undergo Coulombic attractive interactions with anionic headgroups adsorbed at the micellar surface in aqueous SDS whereas HMIm(+) interact through hydrophobic chain-chain attractions as well. Thus, mixed micellization results in formation of vesicles. A micellar phase change from vesicles to micelles takes place at higher [SDS]/[IL] ratios. All of these processes are successfully tracked by the employed techniques.

Magnetic nanoparticles supported ionic liquids improve firefly luciferase properties.

Ionic liquids as neoteric solvents, microwave irradiation, and alternative energy source are becoming as a solvent for many enzymatic reactions. We recently showed that the incubation of firefly luciferase from Photinus pyralis with various ionic liquids increased the activity and stability of luciferase. Magnetic nanoparticles supported ionic liquids have been obtained by covalent bonding of ionic liquids-silane on magnetic silica nanoparticles. In the present study, the effects of [γ-Fe2O3@SiO2][BMImCl] and [γ-Fe2O3@SiO2][BMImI] were investigated on the structural properties and function of luciferase using circular dichroism, fluorescence spectroscopy, and bioluminescence assay. Enzyme activity and structural stability increased in the presence of magnetic nanoparticles supported ionic liquids. Furthermore, the effect of ingredients which were used was not considerable on K(m) value of luciferase for adenosine-5'-triphosphate and also K(m) value for luciferin.

Purification and biochemical characterization of an acidophilic amylase from a newly isolated Bacillus sp. DR90.

An acidophilic and Ca(2+)-independent amylase was purified from a newly isolated Bacillus sp. DR90 by ion-exchange chromatography, and exhibited a molecular weight of 68.9 kDa by SDS-PAGE. The optimum pH and temperature of the enzyme were found to be 4.0 and 45 °C, respectively. The enzyme activity was increased by Ba(2+), Fe(2+) and Mg(2+), and decreased by Hg(2+) and Zn(2+), while it was not affected by Na(+), K(+), phenylmethylsulfonyl fluoride and ß-mercaptoethanol. Ca(2+) and EDTA did not have significant effect on the enzyme activity and thermal stability. The values of K m and V max for starch as substrate were 4.5 ± 0.13 mg/ml and 307 ± 12 µM/min/mg, respectively. N,N-dialkylimidazolium-based ionic liquids such as 1-hexyl-3-methylimidazolium bromide [HMIM][Br] have inhibitory effect on the enzyme activity. Thin layer chromatography analyses displayed that maltose and glucose are the main products of the enzyme reaction on starch. Regarding the features of the enzyme, it may be utilized as a novel candidate for industrial applications.

Improvement of thermostability and activity of firefly luciferase through [TMG][Ac] ionic liquid mediator.

Firefly luciferase catalyzes production of light from luciferin in the presence of Mg(2+)-ATP and oxygen. This enzyme has wide range of applications in biotechnology and development of biosensors. The low thermal stability of wild-type firefly luciferase is a limiting factor in most applications. Improvements in activity and stability of few enzymes in the presence of ionic liquids were shown in many reports. In this study, kinetic and thermal stability of firefly luciferase from Photinus pyralis in the presence of three tetramethylguanidine-based ionic liquids was investigated. The enzyme has shown improved activity in the presence of [1, 1, 3, 3-tetramethylguanidine][acetate], but in the presence of [TMG][trichloroacetate] and [TMG][triflouroacetate] activity, it decreased or unchanged significantly. Among these ionic liquids, only [TMG][Ac] has increased the thermal stability of luciferase. Incubation of [TMG][Ac] with firefly luciferase brought about with decrease of K(m) for ATP.