Preparation of Fe3O4@5,10‐dihydropyrido[2,3‐b]quinoxaline‐7,8‐diol copper complex: A capable nanocatalyst for the green synthesis of 1‐substituted 1H‐tetrazoles

Fe₃O₄ magnetic nanoparticles functionalized with 5,10‐dihydropyrido[2,3‐b]quinoxaline‐7,8‐diol were synthesized as was their complex with copper as a novel nanomagnetic iron oxide catalyst via a simple and green method, and characterized using various techniques. The capability of the catalyst was evaluated in the one‐pot three‐component synthesis of different tetrazoles, which showed very good results. Mild reaction conditions, good reusability and simple magnetic work‐up make this methodology interesting for the efficient synthesis of tetrazoles.     

Suzuki–Miyaura coupling reaction in water in the presence of robust palladium immobilized on modified magnetic Fe3O4 nanoparticles as a recoverable catalyst

Aryl halides and especially inactive aryl chlorides were coupled to benzenoid aromatic rings in a Suzuki–Miyaura coupling reaction in the absence of organic solvents and toxic phosphine ligands. The reaction was catalysed by a recoverable magnetic nanocatalyst, Pd@Fe₃O₄, in aqueous media. This method is green, and the catalyst is easily removed from the reaction media using an external magnetic field and can be re‐used at least 10 times without any considerable loss in its activity. The catalyst was characterized using scanning and transmission electron microscopies, thermogravimetric analysis, inductively coupled plasma spectroscopy, Fourier transform infrared spectroscopy, CHN analysis, X‐ray diffraction and vibrating sample magnetometry.     

Fe3O4@SiO2@propyl‐ANDSA: A new catalyst for the synthesis of tetrazoloquinazolines

In this paper, a mild and green protocol has been developed for the synthesis of quinazoline derivatives. The catalytic activity of 7‐aminonaphthalene‐1,3‐disulfonic acid‐functionalized magnetic Fe₃O₄ nanoparticles (Fe₃O₄@SiO₂@Propyl–ANDSA) was investigated in the one‐pot synthesis of new derivatives of tetrahydrotetrazolo[1,5‐a]quinazolines and tetrahydrobenzo[h]tetrazolo[5,1‐b]quinazolines from the reaction of aldehydes, 5‐aminotetrazole, and dimedone or 6‐methoxy‐3,4‐dihyronaphtalen‐1(2H)‐one at 100 °C in H₂O/EtOH as the solvent. The catalyst was characterized before and after the organic reaction. Fe₃O₄@SiO₂@Propyl–ANDSA showed remarkable advantages in comparison with previous methods. Advantages of the method presented here include easy purification, reusability of the catalyst, green and mild procedure, and synthesis of new derivatives in high yields within short reaction time.     

Silver nanoparticles immobilized onto poly(4‐vinylpyridine)‐functionalized magnetic nanoparticles: A robust magnetically recyclable catalyst for oxidant‐free alcohol dehydrogenation

A heterogeneous and recyclable catalyst with a high loading of silver nanoparticles was synthesized via the silver nanoparticles being supported onto the surface of magnetic nanoparticles coated with poly(4‐vinylpyridine). The synthesized catalyst was used in the dehydrogenation of alcohols to corresponding carbonyl compounds. A broad diversity of alcohols was converted into their corresponding carbonyl compounds in excellent yields. The catalyst was easily recovered by applying an external magnetic field and reused for seven reaction cycles without considerable loss of activity. The catalyst was fully characterized using various techniques.     

Introducing Fe2+ into Nickel–Iron Layered Double Hydroxide: Local Structure Modulated Water Oxidation Activity

Exploring materials with regulated local structures and understanding how the atomic motifs govern the reactivity and durability of catalysts are a critical challenge for designing advanced catalysts. Herein we report the tuning of the local atomic structure of nickel–iron layered double hydroxides (NiFe‐LDHs) by partially substituting Ni²⁺ with Fe²⁺ to introduce Fe‐O‐Fe moieties. These Fe²⁺‐containing NiFe‐LDHs exhibit enhanced oxygen evolution reaction (OER) activity with an ultralow overpotential of 195 mV at the current density of 10 mA cm^?2, which is among the best OER catalytic performance to date. In‐situ X‐ray absorption, Raman, and electrochemical analysis jointly reveal that the Fe‐O‐Fe motifs could stabilize high‐valent metal sites at low overpotentials, thereby enhancing the OER activity. These results reveal the importance of tuning the local atomic structure for designing high efficiency electrocatalysts.     

Design and Synthesis of Powerful Capsule Catalysts Aimed at Applications in C1 Chemistry and Biomass Conversion

Tandem catalytic reaction is a promising strategy to improve the utilization efficiency of energy and resources. The conventional hybrid catalysts cannot readily realize the precisely controlled synthesis of target products due to the unrestricted, open reaction environment. Assembling the hybrid catalyst with multiple active sites into core‐shell structured capsule catalyst is one of the most effective ways to enhance the selectivity of desired products during a tandem catalysis process, because the core‐shell structure offers a space‐confined reaction field and synergistic effect. This review describes our recent progresses on the design and synthesis of core‐shell structured zeolite capsule catalysts developed for C1 chemistry and biomass conversion. The various synthesis methods for constructing the well‐defined zeolite capsule catalysts are described in detail. The applications of the capsule catalysts in catalysis, including the middle isoparaffins synthesis from syngas, one‐step synthesis of dimethyl ether, and liquid‐phase tandem reaction of glycerol conversion, are discussed, respectively. Our perspectives regarding the challenges and opportunities for future research in the field are also provided.     

Kinetics and mechanistic aspects on electron‐transfer process for permanganate oxidation of poly(ethylene glycol) in aqueous acidic solutions in the presence and absence of Ru(III) catalyst

The kinetics and mechanism of oxidation of poly(ethylene glycol) (PEG) by the permanganate ion as a multiequivalent oxidant in aqueous perchlorate solutions at an ionic strength of 2.0 mol dm⁻³ has been investigated spectrophotometrically. The reaction kinetics was found to be of complex in nature. The pseudo–first‐order plots showed curves of inverted S‐shape, consisting of two distinct stages throughout the entire course of reaction. The first stage was relatively slow, followed by a fast reaction rate at longer time periods. The first‐order dependence in [MnO₄⁻], fractional first‐order dependence in [H⁺], and fractional first‐order kinetics in the PEG concentration for the first stage have been revealed in the absence of the Ru(III) catalyst. The influence of the Ru(III) catalyst on the oxidation kinetics has been examined. The oxidation was found to be catalyzed by the added Ru(III) catalyst. The First‐order dependence on the catalyst and zero order with respect to the oxidant concentrations have been observed. The kinetic parameters have been evaluated, and a tentative reaction mechanism consistent with the kinetic results is suggested and discussed.     

A novel fast method for aqueous derivatization of THC,OH‐THC and THC‐COOH in human whole blood and urine samples for routine forensic analyses

A novel aqueous in situ derivatization procedure with propyl chloroformate (PCF) for the simultaneous, quantitative analysis of Δ⁹‐tetrahydrocannabinol (THC), 11‐hydroxy‐Δ⁹‐tetrahydrocannabinol (OH‐THC) and 11‐nor‐Δ⁹‐tetrahydrocannabinol‐carboxylic acid (THC‐COOH) in human blood and urine is proposed. Unlike current methods based on the silylating agent [N,O‐bis(trimethylsilyl)trifluoroacetamide] added in an anhydrous environment, this new proposed method allows the addition of the derivatizing agent (propyl chloroformate, PCF) directly to the deproteinized blood and recovery of the derivatives by liquid–liquid extraction. This novel method can be also used for hydrolyzed urine samples. It is faster than the traditional method involving a derivatization with trimethyloxonium tetrafluoroborate. The analytes are separated, detected and quantified by gas chromatography–mass spectrometry in selected ion monitoring mode (SIM). The method was validated in terms of selectivity, capacity of identification, limits of detection (LOD) and quantification (LOQ), carryover, linearity, intra‐assay precision, inter‐assay precision and accuracy. The LOD and LOQ in hydrolyzed urine were 0.5 and 1.3 ng/mL for THC and 1.2 and 2.6 ng/mL for THC‐COOH, respectively. In blood, the LOD and LOQ were 0.2 and 0.5 ng/mL for THC, 0.2 and 0.6 ng/mL for OH‐THC, and 0.9 and 2.4 ng/mL for THC‐COOH, respectively. This method was applied to 35 urine samples and 50 blood samples resulting to be equivalent to the previously used ones with the advantage of a simpler method and faster sample processing time. We believe that this method will be a more convenient option for the routine analysis of cannabinoids in toxicological and forensic laboratories.     

Photochromic dihetarylethenes. 11. Synthesis and photochromic properties of diarylethenes containing furan or furopyrimidine bridges

Procedures were developed for the synthesis of substituted bis(2,5-dimethyl-3-thienyl)furans based on 1,2-bis(2,5-dimethyl-3-thienyl)-2-hydroxyethanone. Dithienylethene structures in which the ethene fragment is involved in the furan or furopyrimidine system possess photochromic properties and their open forms exhibit fluorescence.