Pseudo-poly(amino acid)s: study on construction and characterization of novel chiral and thermally stable nanostructured poly(ester-imide)s containing different trimellitylimido-amino acid-based diacids and pyromellitoyl-tyrosine-based diol

A new class of chiral and potentially biodegradable poly(ester-imide)s (PEI)s as pseudo-poly(amino acid)s (PAA)s bearing natural amino acids in the main chain was synthesized. In this investigation, N,N′-(pyromellitoyl)-bis-(L-tyrosine dimethyl ester) as a biodegradable optically active diphenol and synthesized trimellitic anhydride-derived dicarboxylic acids containing different natural amino acids such as S-valine, L-methionine, L-leucine, L-isoleucine, and L-phenylalanine were used for direct polyesterification. With the aim of tosyl chloride/pyridine/N,N′-dimethylformamide system as a condensing agent, the new optically active PEIs were obtained in good yields and moderate inherent viscosity up to 0.42 dL/g. The obtained polymers were characterized with FT-IR, ¹H-NMR, X-ray diffraction (XRD), field emission scanning electron microscopy, elemental, and thermogravimetric analysis techniques. These polymers show high solubility in organic solvents, such as N,N′-dimethyl acetamide, N-methyl-2-pyrrolidone, and sulfuric acid at room temperature, and are insoluble in solvents, such as methylene chloride, cyclohexane, and water. Morphology probes showed these pseudo-poly(amino acid)s were noncrystalline and nanostructured polymers. On the basis of thermogravimetric analysis data, such PAAs are thermally stable and can be classified as self-extinguishing polymers. In addition due to the existence of amino acids in the polymer backbones these pseudo-PAAs not only are optically active but also are expected to be biodegradable and therefore could be classified under eco-friendly polymers.     

A convenient synthesis of bis(indolyl)alkanes under ultra sonic irradiation using silica-supported Preyssler nano particles

Bis(indolyl)alkanes have been synthesised in excellent yields in the presence of catalytic amount of silica-supported Preyssler nano particles as green, reusable and efficient catalyst under ultra sonic irradiation.     

Nano-TiO_2:An eco-friendly alternative for the synthesis of quinoxalines

Nano-TiO₂ as an eco-friendly and efficient nanocatalyst was applied for quinoxaline preparation with improved yield.In this protocol,diketones and 1,2-diamines were condensed in the presence of catalyst at room temperature.     

Palladium nanoparticles immobilized on sepiolite–cyclodextrin nanosponge hybrid: Efficient heterogeneous catalyst for ligand‐ and copper‐free C─C coupling reactions

A novel hybrid system composed of sepiolite clay and cyclodextrin nanosponge (CDNS) was prepared via reaction of Cl‐functionalized sepiolite with amine‐functionalized CDNS. CDNS–sepiolite was then applied for immobilization of Pd(0) nanoparticles. The resulting hybrid system, Pd@CDNS‐sepiolite, was characterized using various techniques and successfully used as an efficient and heterogeneous catalyst for ligand‐ and copper‐free Sonogashira and Heck coupling reactions under mild reaction conditions. Recycling experiments confirmed that Pd@CDNS‐sepiolite was recyclable and could be used for several consecutive reaction runs with slight Pd leaching and loss of catalytic activity.     

One-pot Synthesis of 3-Aminoimidazo[1,2-a]pyridines Catalyzed by Heteropolyacids

Condensation of aldehydes, isonitriles and 2‐aminopyridines in the presence of H₃PMo₁₂O₄₀ affords different derivatives of 3‐aminoimidazo[1,2‐a]pyridine in good to excellent yields.     

68Ga-5, 10, 15, 20-Tetrakis (2, 4, 6-trimethoxy phenyl) porphyrin: a novel radio-labeled porphyrin complex for positron emission tomography

Journal of Radioanalytical and Nuclear Chemistry - Porphyrins and 68Ga have emerged as novel synergic options for PET applications so the idea of preparation of a novel porphyrin complex using this...     

Coexistence of paramagnetism and ferromagnetism in Fe-TiO2 nanoparticle

Magnetic properties of pure and Fe doped rutile TiO₂ and TiO_2-ε are investigated using the first principle density functional theory. The results show that the considered systems are ferromagnetic. Furthermore, the origin of ferromagnetism is discussed and it is found that the double exchange and super-exchange are the main interactions in these compounds. Based on the calculations, the magnitude of the magnetic moment depends on the concentration of impurities and oxygen vacancies and the largest magnetic moment corresponds to the Fe_xTi_1-xO_2-ε. Moreover, using a model based on the bound magnetic polarons, the coexistence of ferromagnetic and paramagnetic phases can occur in Fe_xTi_1-xO₂ containing different impurity ions such as Fe⁺² and Fe⁺³ with different Curie temperatures. The finding may presents the potential application of the considered system as diluted magnetic semiconductor.     

Expedient multicomponent synthesis of a small library of some novel highly substituted pyrido[2,3-d]pyrimidine derivatives mediated and promoted by deep eutectic solvent and in vitro and quantum mechanical study of their antibacterial and antifungal activities

Molecular Diversity - A facile and efficient catalyst- and oxidant-free multicomponent synthesis of a small library of highly substituted pyrido[2,3-d]pyrimidine derivatives is reported. The...     

Nanofluid flow in a catheterized tapered artery

Journal of Thermal Analysis and Calorimetry - This study was conducted with the aim of investigating the Newtonian nanofluid flow in a catheterized tapered artery through using a completely...