A novel thermo-sensitive nanogel composing of poly(<Emphasis Type="Italic">N</Emphasis>-isopropylacrylamide) grafted onto alginate-modified graphene oxide for hydrophilic anticancer drug delivery

Nanogels have been demonstrated to be desirable for hydrophilic anticancer drug delivery. This study presents a novel nanogel consisting of sodium alginate-modified graphene oxide (SA-GO) and N-isopropylacrylamide (NIPAM) for sustained delivery of doxorubicin (DOX) drug. The PNIPAM/SA-GO nanogel was studied by various techniques including scanning electron microscopy, atomic force microscopy, dynamic light scattering, Fourier transform infrared spectroscopy, and thermo-gravimetric analysis. Subsequently, the thermo-responsive behavior of the PNIPAM/SA-GO nanogel was investigated by UV–Vis spectroscopy. DOX was successfully loaded into the PNIPAM/SA-GO nanogel in order to study entrapment efficiency and drug release behavior. Moreover, biocompatibility of the DOX-loaded PNIPAM/SA-GO nanogel was examined against Hella cells and was compared with free PNIPAM/SA-GO nanogel and DOX. This work offers that the nanogels could be developed further as an effective bioactive molecule delivery system.     

Potentiometric study of complexation of phenylaza-15-crown-5, 4-nitrobenzo-15-crown-5 and dibenzopyridino-18-crown-6 and other derivative of 18-crowns-6 with Na+ ion in methanol

The complexation reaction of phenylaza-15-crown-5, and 4-nitrobenzo-15-crown-5, benzo-15-crown-5 and dibenzopyrdino-18-crwon-6, dibenzo-18-crown-6,dicyclohexyl-18-crown-6(cis and trans), and 18-crown-6 with Na⁺ ion in methanol have been studied by potentiometric method. The Na⁺ ion-selective electrode has been used both as indicator and reference electrode. The stoichiometry and stability constants of complexes of these crown ethers with sodium ion were evaluated by MINIQUAD program. The major trend of stability of resulting complexes of these macrocycle with Na⁺ ion varied in the order DCY18C6 > DB18C6 > 18C6 > DBPY18C6 > phenylaza-15C5 > benzo-15C5 > 4-nitrobenzo-15C5. The obtained results in particular stability constant of complexes of DBPY18C6, phenylaza-15C5 and 4-nitrobenzo-15C5 with sodium ion in comparison with other crowns ether are novel, and interesting.     

Organosulfur phosphonium salt-mediated synthesis of functionalized thiopyran derivatives

Methyl 4-oxotetrahydro-2H-thiopyran-3-carboxylate as a CH-acid undergoes a mild reaction with acetylenic esters in the presence of triphenylphosphine to produce phosphorus ylides possessing thiopyran-4-one ring moiety. The resulted phosphorus ylides when heated in toluene afforded functionalized thiopyran derivatives through intramolecular Wittig reaction.     

Preparation of Zinc (II) and cadmium (II) complexes of the tetradentate Schiff base ligand 2-((E)-(2-(2-(pyridine-2-yl)- ethylthio)ethylimino)methyl)-4-bromophenol (PytBrsalH)

We describe the synthesis and characterization of two new zinc (II) and cadmium (II) complexes of the tetradentate dissymmetric Schiff base ligand 2-((E)-(2-(2-(pyridine-2-yl)ethylthio)ethylimino)methyl)-4-bromophenol (PytBrsalH), prepared from 1-(2-pyridyl)-3-thia-5-aminopentane (pyta) and 5-bromosalicylaldehyde. The complexes were synthesized by treating an ethanolic solution of the ligand with equimolar amounts of appropriate metal salts in 1 M methanolic solution of NaOH or alternatively, by a more direct route in which the two reactants are added to a solution of the ligand immediately after formation of the latter and prior to any isolation. The complexes were characterized by elemental analysis, FTIR, (1)H-NMR, electronic spectra and molar conductivity. According to obtained data, the probable coordination geometries of zinc and cadmium in these complexes with mixed N, S and O donor atoms are tetrahedral- and octahedral-like,respectively. Both complexes were found to be 1:1 electrolyte systems in acetonitrile.     

Highly luminescent lead sulfide nanocrystals in organic solvents and water through ligand exchange with poly(acrylic acid)

Hydrophobic lead sulfide quantum dots (PbS/OA) synthesized in the presence of oleic acid were transferred from nonpolar organic solvents to polar solvents such as alcohols and water by a simple ligand exchange with poly(acrylic acid) (PAA). Ligand exchange took place rapidly at room temperature When a colloidal solution of PbS/OA in tetrahydrofuran (THF) was treated with excess PAA, the PbS/PAA nanocrystals that formed were insoluble in hexane and toluene but could be dissolved in methanol or water, where they formed colloidal solutions that were stable for months. Ligand exchange was accompanied by a small blue shift in the band-edge absorption, consistent with a small reduction in particle size. While there was a decrease in quantum yield associated with ligand exchange and transfer to polar solvents, as is commonly found for colloidal quantum dots, the quantum yields determined were impressively high: PbS/OA in toluene (82%) and in THF (58%); PbS/PAA in THF (42%) and in water (24%). The quantum yields for the PbS/PAA solutions decreased over time as the solutions were allowed to age in the presence of air.     

Simple and efficient protocol for the synthesis of benzoxazole,benzoimidazole and benzothiazole heterocycles using Fe(Ⅲ)–Schiff base/SBA-15 as a nanocatalyst

Benzimidazoles, benzoxazoles, and benzothiazoles derivatives were synthesized from condensation of aldehydes and 1,2-phenylenediamine or ortho-aminophenol or ortho-aminothiophenol in the presence of catalytic amount of Fe(Ⅲ)–Schiff base/SBA-15 in water medium. Short reaction times, good to excellent yields, easy availability, reusability, and use of an eco-friendly catalyst are some of the significant attributes of the present method.     

Effect of Functionalized Magnetite Nanoparticles and Diaminoxanthone on the Curing,Thermal Degradation Kinetic and Corrosion Property of Diglycidyl Ether of Bisphenol A-Based Epoxy Resin

To prepare a high-performance epoxy resin with excellent thermal, chemical and corrosion stability, diaminoxanthone（DAX） was used to cure diglycidylether of bisphenol-A（DGEBA）-based epoxy resin and blend of DGEBA with functionalized Fe3O4 nanoparticles. Kinetic parameters of curing and thermal degradation of epoxy resin systems were estimated by differential scanning calorimetry（DSC） and thermogravimetric analysis（TGA）, respectively. The 10% weight loss temperature has been increased from 340 °C to 366 °C and there was an increase in the char yield from 32.6% to 45.3% for the above systems. The corrosion performance of epoxy coated carbon steel was examined by potentiodynamic polarization, along with immersion test in 1.0 mol/L HCl solution. The results showed that epoxy resins cured with DAX had low tendency to corrosion. In addition, the cured epoxy resin containing 10% Fe3O4 had higher anticorrosion activity than bare DGEBA system. The results showed that functionalized Fe3O4 nanoparticles enhanced char formation and improved the thermal stability as well as anticorrosion activity of the resin.     

Selective Silylation of Alcohols,Phenols and Oximes Using N‐Chlorosaccharin as an Efficient Catalyst under Mild and Solvent‐Free Conditions

Efficient silylation of OH group in alcohols, phenols and oximes is described using a catalytic amount of N‐chlorosaccharin and hexamethyldisilazane (HMDS) under mild and solvent‐free conditions. This silylation reaction can be carried out with excellent and interesting various selectivities.     

Infinitely many solutions for perturbed impulsive fractional differential systems

In this paper, the existence of infinitely many solutions for perturbed systems of impulsive non-linear fractional differential equations including Lipschitz continuous non-linear terms is discussed. The approach is based on variational methods. In addition, examples are presented to illustrate the feasibility and effectiveness of the main results.