Synthesis and Characterization of Novel Heat Resistant,Superparamagnetic Poly(ether-imide) Nanocomposites Containing Xanthene: Representing a Strategy for Improving Thermal Stability of Magnetic Polymer-Based Nanocomposites

Two superparamagnetic and heat resistant xanthene based poly(ether-imide) nanocomposites were successfully synthesized. Field emission scanning electron microscopy, transmission electron microscope, X-ray diffraction, thermal gravimetric analysis, vibrating sample magnetometer, Energy-dispersive X-ray spectroscopy and Fourier-transform infrared (FTIR) techniques were used for studying the morphology, crystalline phase, thermal stability and magnetization properties of the nanocomposites. The neat form of the corresponding poly(ether-imide) was also prepared by thermal imidization method and its structure was confirmed by FTIR, proton nuclear magnetic resonance (¹H NMR), UV–Vis and photoluminescence (PL) spectroscopies. In order to investigate the effects of modifying the surface of Fe₃O₄ nanoparticles on thermal properties of the nanocomposites, the surface of Fe₃O₄ nanoparticles was coated with SiO₂ and polysuccinimide (PSI), sequentially. Then, both the unmodified Fe₃O₄ and surface-modified Fe₃O₄ (Fe₃O₄@SiO₂–PSI) nanoparticles were used as fillers for the polymer matrix. According to the results, the prepared nanocomposites were superparamagnetic and showed higher thermal stability in comparison to the neat poly(ether-imide). Furthermore, poly(ether-imide)/Fe₃O₄@SiO₂–PSI (PIEN 10b) nanocomposite showed higher thermal stability and dispersed better in the polymer matrix [in comparison to poly(ether-imide)/Fe₃O₄ (PIEN 10 a)] due to the presence of imide groups and high hydroxyl content of the functional Fe₃O₄ nanoparticles which caused high interactions between poly(ether-imide) and functional Fe₃O₄. Furthermore, the presence of methyl, ether and bulky xanthene groups in the poly(ether-imide(backbone improved the solubility of the neat polymer in organic solvents. These properties can be very helpful for extending new applications of poly(ether-imide)s.     

Preparation and characterization of a novel host (zeolite NaY)/guest (copper(II) complex of a new bidentate Schiff base ligand) nanocomposite material (HGNM): a comparison between catalytic reactivity of free and encapsulated complexes in oxidation of benzyl alcohol and aldol condensation

A copper(II) complex of 4-((E)-(4-(1H-benzo[d]imidazol-2-yl)phenyl)diazenyl)-2-((E)-(4-hydroxyphenylimino) methyl)phenol (HL) was encapsulated in zeolite NaY by flexible ligand method. The structure of encapsulated complex was characterized by spectroscopic (electronic and FT-IR), XRD, TGA, BET and elemental analysis data. Furthermore, catalytic activity of the neat and encapsulated complexes was studied in oxidation of benzyl alcohol and aldol condensation. The encapsulated complex was more reactive and stable than the corresponding free complex. Nanocomposite material was enough stable to be reused for several times. Finally, the reaction parameters were optimized for oxidation of benzyl alcohol and aldol condensation.     

Copper containing poly(melamine-terephthaldehyde)-magnetite mesoporous nanoparticles: a highly active and recyclable catalyst for the synthesis of benzimidazole derivatives

The surface of Fe₃O₄ magnetic nanoparticles was modified with silica shell and copper containing poly(melamine-terephthaldehyde) through a facile and efficient method. The structure of these nanoparticles was characterized by using the following techniques: Fe-SEM, TGA/DTA, XRD, FTIR, VSM, BET, EDS and XPS. Then, this compound was used as a magnetic, reusable and heterogeneous nano-catalyst for the synthesis of benzimidazole derivatives. The represented method proved that this novel material could show great catalytic performance and produce the desired products with high purity and excellent yields in short times. The efficiency of this catalyst was also compared with the catalysts which were previously reported for the synthesis of benzimidazoles. It was clear from this comparison that our catalyst was distinguished from the previous ones due to its inherent magnetic properties so this compound can be one of the best catalysts for the synthesis of benzimidazoles. The other advantages of the represented procedure include simple conditions, environmentally friendliness, high recovery ability, easy work-up and low cost.     

Preparation of Core/Shell CaO@SiO2-SO3H as a Novel and Recyclable Nanocatalyst for One-Pot Synthesize of Dihydropyrano[2,3-c]Pyrazoles and Tetrahydrobenzo[b]Pyrans

Silicon - The core/shell CaO@SiO2-SO3H nanoparticles were prepared by stabilizing of sulfonic acid on the surface of silica-coated CaO nanoparticles. The structure of CaO@SiO2-SO3H was...