Magnetic‐based picolinaldehyde–melamine copper complex for the one‐pot synthesis of hexahydroquinolines via Hantzsch four‐component reactions

A picolinaldehyde–melamine copper complex was loaded on a magnetic Fe₃O₄ core, so that it contained 0.33 mmol of Cu per gram, and was used as an efficient catalyst. The as‐synthesized catalyst was characterized using various techniques, including Fourier transform infrared spectroscopy, X‐ray diffraction, energy‐dispersive X‐ray spectroscopy, field emission scanning electron microscopy, transmission electron microscopy, vibrating sample magnetometry and thermogravimetric analysis. The catalyst was used to activate the raw materials in the synthesis of hexahydroquinoline derivatives in one‐pot four‐component reactions. Low reaction time (minutes versus half an hour), solvent‐free condition and magnetically separable catalyst are some salient features of the developed catalyst. Also, the optimum amount of catalyst and temperature were determined as 0.07 g and 87.6 °C, respectively, which were obtained using response surface methodology and optimization techniques.     

Nickel(II) Schiff base complex supported on nano‐titanium dioxide: A novel straightforward route for preparation of supported Schiff base complexes applying 2,4‐toluenediisocyanate

For the first time, a novel, straightforward and inexpensive route for immobilization of metals in Schiff base complex form is reported applying 2,4‐toluenediisocyanate as a precursor of primary amine group. A nickel(II) Schiff base complex supported on nano‐TiO₂ was designed and synthesized as an effective heterogeneous nanocatalyst for organic reactions, and well characterized using various techniques such as Fourier transform infrared spectroscopy, field emission scanning electron microscopy, transmission electron microscopy, X‐ray diffraction, energy‐dispersive X‐ray analysis and thermogravimetric analysis. The catalytic efficiency of the complex was evaluated in selective oxidation of sulfide to sulfoxide by hydrogen peroxide as an oxidant under solvent‐free conditions at room temperature, which successfully resulted in high yield and high conversion of products. Effective factors including solvent type, oxidant and catalyst amount were also optimized. The catalyst shows outstanding reusability and could be impressively recovered for six consecutive cycles without significant change of its catalytic efficiency.     

Quantum Watermarking Using Entanglement Swapping

Digital watermarking is the process of embedding information into a digital signal in a way that is difficult to remove. In this article a secure quantum watermarking using entanglement swapping is proposed. Here the entanglement swapping is employed to build up a hidden layer of secure message under the conventional first layer of secure information sequence. In this protocol by insuring the security of transmission of the first layer of information sequence the security of the hidden secret messages is also proved to be reliable regardless of whether the hidden channel has been detected or not.     

Mn(II) and VO(IV) Schiff base complexes encapsulated in nanocavities of zeolite-Y: catalytic activity toward oxidation of alkenes and reduction of aldehydes

Oxovanadium(IV) and manganese(II) complexes of two Schiff base ligands, bis(2,4-dihydroxyacetophenone)-1,2-propandiimine (H₂L₁) and bis(2,4-dihydroxyacetophenone)-ethylenediimine (H₂L₂) were synthesized and characterized. The encapsulation of these complexes in the nanocavities of zeolite-Y was achieved by a flexible ligand method. The prepared heterogeneous catalysts have been characterized by FTIR, NMR and atomic absorption spectroscopy, X-ray diffraction patterns, scanning electron microscopy and BET. The catalytic activities of the encapsulated complexes were studied in the oxidation of alkenes with H₂O₂ and the reduction of aldehydes with NaBH₄. In most cases, the manganese (II) complexes (MnL₁-Y, MnL₂-Y) showed better activity than the oxovanadium (IV) complexes (VOL₁-Y, VOL₂-Y) in both oxidation of alkenes and reduction of aldehydes. The catalytic activity of the recovered catalysts was compared with the fresh ones.     

Covalent Functionalization of Pristine and Ga-Doped Boron Phosphide Nanotubes with Imidazole

Abstract

Density functional theory (DFT) calculations at the B3LYP/6–31G* level were performed to investigate covalent functionalization of imidazole on pristine (in gas and H₂O phases) and Ga-doped BPNT models in terms of energetic, geometric, and electronic properties. The results show that imidazole, as a functional group, prefers to be adsorbed via its nitrogen atom on the pristine, Ga_B, and Ga_P nanotube models. The adsorption energy of imidazole on the (6,0) zigzag BPNT in gas and solvent phases is ?0.76 and ?1.11 eV, respectively, and about 0.38 and 0.43 electron are transferred from the imidazole to nanotube in the phases. The presence of a polar solvent increases the electron donor of imidazole molecule. The results show that Ga doping can significantly enhance the adsorption energy of imidazole on the nanotube models to about 95%.

Moreover, the imidazole adsorption on the pristine and Ga-doped BPNT models has not significant changes in the energy gap of the nanotube models and it is slightly changed after covalent functionalization process. This study may provide new insight to the development of functionalized boron phosphide nanotubes for generation of the new hybrid compounds especially in drug delivery systems for virtual applications.     

Coating Cellulosic Material with Ag Nanowires to Fabricate Wearable IR-Reflective Device for Personal Thermal Management: The Role of Coating Method and Loading Level

Textiles coated with silver nanowires (AgNWs) are effective at suppressing radiative heat loss without sacrificing breathability. Many reports present the applicability of AgNWs as IR-reflective wearable textiles, where such studies partially evaluate the parameters for practical usage for large-scale production. In this study, the effect of the two industrial coating methods and the loading value of AgNWs on the performance of AgNWs-coated fabric (AgNWs-CF) is reported. The AgNWs were synthesized by the polyol process and applied onto the surface of cotton fabric using either dip- or spray-coating methods with variable loading levels of AgNWs. X-ray diffraction, scanning electron microscopy (SEM), infrared (IR) reflectance, water vapor permeability (WVP), and electrical resistance properties were characterized. The results report the successful synthesis of AgNWs with a 30 μm length. The results also show that the spray coating method has a better performance for reflecting the IR radiation to the body, which increases with a greater loading level of the AgNWs. The antibacterial results show a good inhibition zone for cotton fabric coated by both methods, where the spray-coated fabric has a better performance overall. The results also show the coated fabric with AgNWs maintains the level of fabric breathability similar to control samples. AgNWs-CFs have potential utility for cold weather protective clothing in which heat dissipation is attenuated, along with applications such as wound dressing materials that provide antibacterial protection.