Green synthesis of the 1-substituted 1H-1, 2, 3, 4-tetrazoles over bifunctional catalyst based on copper intercalated into Mg/Al hydrotalcite modified magnetite nanoparticles

An effective one-pot, convenient process for the synthesis of 1- substituted 1H-tetrazoles from triethyl orthoformate, amines, and sodium azide is described using copper (II) doped and immobilized on functionalized magnetic hydrotalcite (Fe₃O₄/HT-NH₂ Cu^II) as a novel recyclable catalyst. The application of this catalyst allows the synthesis of a variety of tetrazoles in good to excellent yields in water. The new catalyst was characterized using Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), thermogravimetric analysis (TGA), vibration sample magnetometry (VSM) and inductively coupled plasma analysis (ICP-OES). This new procedure offers several advantages such as short operational simplicity, practicability, and applicability to various substrates and the absence of any tedious workup or purification. The loading amount of Cu^II (doped and immobilized) on functionalized magnetic hydrotalcite was indicated to be 4.66 mmol g⁻¹, obtained from the ICP-OES analysis. Also, the excellent catalytic performance, thermal stability, and separation of the catalyst make it an excellent heterogeneous system and a useful alternative to other heterogeneous catalysts. Also, the catalyst could be magnetically separated and reused six times without significant loss of catalytic activity.     

Effective one-pot synthesis of tetrahydrobenzo[b]pyran derivatives using nickel Schiff-base complex immobilized on iron oxide nanoparticles

Nickel Schiff-base complex immobilized on silica-coated Fe₃O₄ as a heterogeneous catalyst was designed and characterized by different techniques, such as Fourier transform infrared (FT-IR), X-ray powder diffraction (XRD), field emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectroscopy (EDX), inductively coupled plasma (ICP) and vibrating sample magnetometry (VSM) thermogravimetric analysis (TGA), and Brunauer–Emmett–Teller (BET). The synthesized nanocatalyst has been explored as a new and efficient recyclable heterogeneous catalyst for the one-pot three-component synthesis of tetrahydrobenzo[b]pyran derivatives. The reaction proceeds smoothly to supply the respective products in excellent yields and low reaction times. The catalyst can be easily recovered by a magnetic field and reused for eight consecutive reaction cycles without significant loss of activity.     

Preparation and characterization of a novel DABCO-based ionic liquid supported on Fe3O4@TiO2 nanoparticles and investigation of its catalytic activity in the synthesis of quinazolinones

In this study, quinazolinone derivatives have been synthesized via a suitable and efficient procedure by one-potmulti-component reactions of 3-amino-1,2,4-triazole or 2-aminobenzimidazole, dimedone and aromatic aldehydes in the presence of Fe₃O₄@TiO₂-IL as nanocatalyst under solvent-free condition. The products were prepared in good to excellent yields using Fe₃O₄@TiO₂-IL magnetic nanocatalyst. The Fe₃O₄@TiO₂ magnetic nanoparticles (MNPs) were prepared using beet juice extract and functionalized with IL based on DABCO. Moreover, the core-shell structured magnetic Fe₃O₄@TiO₂-IL has been characterized by different techniques such as ¹H-NMR, FT-IR, VSM, XRD, SEM, TGA, TEM and EDX. To the best of our knowledge, the prepared ionic liquid displayed a good protective and activator agent for magnetic nanocatalyst.     

Silver chloride supported on Vitamin B1 -Organometallic magnetic catalyst: synthesis,density functional theory study and application in A3-coupling reactions

A highly efficient Fe₃O₄@VitB₁–Ag(I) magnetic catalyst has been obtained using surface modification of Fe₃O₄. To this end, silver chloride was immobilized on Fe₃O₄ nanoparticles via vitamin B₁ biomolecules. The synthesized biocompatible magnetic catalyst was applied in an A³-coupling reaction in the presence of aldehyde, amine and phenyl acetylene under solvent-free conditions and afforded the desired products in excellent yields. Also, interactions between metal and ligand in the Fe₃O₄@VitB₁–Ag(I) were studied using theoretical calculations.     

Biohybrid Organic Heterostructure Based on Chlorophyll-Bacteriochlorophyll Aggregates for Ecofriendly Hydrogen Production

Hydrogen energy is an abundant, clean, sustainable and environmentally friendly renewable energy source. Therefore, the production of hydrogen by photocatalytically splitting water on semiconductors has been considered in recent years as a promising and sustainable strategy for converting solar energy into chemical energy to replace conventional energy sources and to solve the growing problem of environmental pollution and the global energy crisis. However, highly efficient solar-driven photocatalytic hydrogen production remains a huge challenge due to the poor visible light response of available photocatalytic materials and the low efficiency of separation and transfer of photogenerated electron-hole pairs. In the present work, organic heterojunction structures based on bacteriochlorophyll (BChl) and chlorophyll (Chl) molecules were introduced and used for solar-driven photocatalytic hydrogen production from water under visible light. Also, noble metal-free photocatalyst was successfully constructed on Ti₃C₂T_x nanosheets by simple successive deposition of Chl and BChl, which was used for the photocatalytic splitting water to hydrogen evolution reaction (HER). The results show that the optimal BChl@Chl@Ti₃C₂T_x composite has a high HER performance with 114 μmol/h/g_cat, which is much higher than the BChl@Ti₃C₂T_x and Chl@Ti₃C₂T_x composites.     

Recyclable MoO3 nanobelts for photocatalytic degradation of Rhodamine B by near infrared irradiation

Molybdenum trioxide (MoO₃) represented an excellent photocatalytic performance with many applications, including degradation of organic contaminants and splitting of water. This paper presented a new route to synthesize MoO₃ nanobelts with high aspect ratios and crystallinity by a hydrothermal technique. This work showed that the as-synthesized nanobelts exhibited strong photocatalytic activity to degrade an organic dye of Rhodamine B (RhB) in aqueous solution under the exposure of the light source in the near infrared wavelength range, significantly improving the photocatalytic activity of the nanobelts. The results also showed that for a small concentration of RhB at 7.5 mg/L a complete photodegradation (for a given MoO₃ nanobelts quantity of 0.1 g) can be reached after exposing for 60 min. For all concentrations of the RhB solution, the photodegradation exhibited an exponential dependence on the exposure time followed by a sudden shutdown, but no complete photodegradation can be reached. Also, the residual quantity of RhB in solution after the photocatalytic reaction was determined by the initial RhB concentration. The photocatalytic degradation can be interpreted by the pseudo–first-order equation for the absorption of liquid/solid based on solid capacity; thus, photocatalytic degradation can be attributed to the interaction between the photoexcited electrons in the substrate and the antibonding orbital of the RhB in solution. The sudden shutdown was due to the inability of the photoexcited electrons in the substrate hopping to the antibonding orbital of RhB in the presence of the RhB intermediate products from the degraded RhB. In addition, this work showed that the photocatalytic reaction can be recovered after a thermal treatment of postreacted MoO₃ nanobelts, enhancing the utilization efficiency of the catalysis.     

PDα‐type distributed learning control for nonlinear fractional‐order multiagent systems

This paper considers the consensus tacking problem for nonlinear fractional‐order multiagent systems by presenting a PD^α‐type iterative learning control update law with initial learning mechanisms. The asymptotical convergence of the proposed distributed learning algorithm is strictly proved by using the properties of fractional calculus. A sufficient condition is derived to guarantee the whole multiagent system achieving an asymptotic output consensus. An illustrative example is given to verify the theoretical results.