Polymer colloids formed by polyelectrolyte complexation of vinyl polymers and polysaccharides in aqueous solution

The polyelectrolyte complex formed from the polyanion and polycation was studied by turbidimetry, static and electrophoretic light scattering, and elementary analysis. Sodium salts of polyacrylate (PA) and heparin (Hep) were chosen as the polyanion, and hydrochloric salts of poly(vinyl amine) (PVA) and chitosan (Chts) as the polycation. Although these vinyl polymers and polysaccharides have remarkably different backbone chemical structures and linear charge densities, all the four combinations PA-PVA, PA-Chts, Hep-PVA, and Hep-Chts provide almost stoichiometric polyelectrolyte complexes which are slightly charged owing to the adsorption of the excess polyelectrolyte component onto the neutral complex. The charges stabilize the complex colloids in aqueous solution of a non-stoichiometric mixture, and the aggregation number of the complex colloids increases with approaching to the stoichiometric mixing ratio. The mixing ratio dependence of the aggregation number for the four complexes is explained by the model proposed in the previous study.     

Synthesis and characterization of fluorine functionalized graphene oxide dispersed quinoline-based polyimide composites having low-k and UV shielding properties

Polyimide nanocomposites having low-k and UV shielding properties have been developed using fluorine functionalized graphene oxide and bis(quinoline amine) based polyimide. The polyimide was synthesized using bis(quinoline amine) and pyromellitic dianhydride at appropriate experimental conditions, and its molecular structure was confirmed through various spectral analysis such as FTIR and NMR. The polyimide (PI) composites were prepared using bis(quinoline amine), pyromellitic dianhydride, and separately filled with 1, 5, 10 wt% of fluorinated graphene oxide (FGO) through in situ polymerization. The polymer composites were characterized using thermo gravimetric analysis (TGA), X-ray powder diffraction (XRD), and scanning electron microscopy (SEM). In addition, the water contact angle, dielectric behavior, and UV–Vis shielding behavior of FGO/PI composites were evaluated. The value of the water contact angle of the polyimide was increased with increment of FGO in the polyimide matrix. The highest water contact angle of polyimide composites observed 108° was obtained for 15 wt% FGO reinforced polyimide composite. The value of the dielectric constant for neat, 1, 5, and 15 wt% FGO reinforced polyimide composites was obtained as 4.5, 3.7, 2.6, and 2.0, respectively. It is also observed from by UV–Vis spectroscopy analysis that the FGO reinforced polyimide composites have good UV shielding behavior.     

Residue valorization: Preparation of recyclable organic amine adsorbent using laterite residue

This study focuses on exploiting the main component of traditional nickel metallurgical waste for use as a valuable material that can be applied in the removal of organic amines from water systems. Silicon compounds from metallurgic waste were converted into dissolvable sodium silicate by roasting the waste with alkali. Silica with adsorption capacity was combined with magnetic NiFe cores by the carbonation decomposition of purified silicate solution. The composite magnetic adsorbent was characterized, and its adsorption mechanism for organic amines was investigated. The effects of the initial trimethylamine concentration, contact time and temperature on the adsorption efficiency of the composite adsorbent towards trimethylamine were investigated. It was found that the adsorption fit the Freundlich mode well. The adsorption kinetics can be described by a pseudo-second-order kinetic model. The adsorption capacity reached 55.8 μg/mg at 293 K. The use of metallurgical waste to prepare the magnetic composite adsorbent has three advantages, which include benefiting the environment by reducing the amount of solid waste and costs associated with constructing and maintaining storage facilities, generating valuable products in an economical manner and conveniently recycling used adsorbents to avoid secondary pollution.     

Synthesis,characterization and biological activity evaluation of new 3- methyl and 4- fluoro isoindoline-1, 3-dione/phthalimide analogues

The convenient route for the synthesis of a series of new Isoindoline-1, 3-dione/phthalimide analogues by condensation of substituted phthalic anhydride with an appropriate Ar-amine is described. Selective phthalimide derivatives were evaluated for their preliminary biological activities against Gram-positive, Gram-negative and fungi strains. These encouraging results could be helpful for the development of new antibacterial or antifungal agents.     

Organocatalytic asymmetric [3 + 3] annulation of isatin N,N'-cyclic azomethine imines with enals: Efficient approach to functionalized spiro N-heterocyclic oxindoles

An unprecedented chiral secondary amine-catalyzed [3 + 3] annulation of isatin N,N'-cyclic azomethine imines with α,β-unsaturated aldehydes was developed. This strategy allowed the construction of structurally novel spiro N-heterocyclic oxindole derivatives in good yields (up to 91%) and good to excellent enantioselectivities (up to >99% ee), albeit with modest diastereoselectivities (up to 3.1:1 dr).     

多组份一锅法合成新型2-取代噻唑-4-甲酸衍生物

以甲醇为溶剂,以醛、胺、硫代乙酸和3-(二甲氨基)-2-异氰基丙烯酸甲酯为原料,经四组份一锅法反应合成了9个新型的2-取代噻唑-4-甲酸衍生物,产率25%~54%,纯度90.3%~100%,其结构经1H NMR,13C NMR和LC-MS表征。     

高效可回收多相催化剂SiO_2-Cu_2O催化伯胺和仲胺苄基化反应(英文)

A mild,effective,and selective procedure is reported for the mono N-benzylation and N,N-dibenzylation of primary amines as well as mono N-benzylation of secondary amines using silicasupported copper(I) oxide in water.The silica-supported Cu2O was generated in situ by the reaction of Fehling solution and glucose at 100 °C onto activated silica.The catalyst was filtered,washed with water,and oven-dried,and was characterized by Fourier transform infrared spectroscopy,thermogravimetric analysis,scanning electron microscopy,transmission electron microscopy,and atomic absorption spectroscopy.The prepared Cu2O-SiO2 was found to be thermally stable up to 325 °C.The copper was uniformly distributed onto the surface of the silica,and the mean particle diameter was 7 nm.The catalyst served as a selective heterogenous catalyst for the N-benzylation of primary and secondary amines.The catalyst is recyclable and was used effectively upto fifth run without a significant loss of catalytic activity.Various reaction solvents including water,acetonitrile,and toluene were screened for N-benzylation of amines,and the success of the aqueous system highlights the low environmental impact of the procedure.     

Tertiary amines as vinyl source for the formations of aryl or pyrrole ring on amido-substitued 1,4-quinone with the assistance of palladium salt

The one-pot synthesis of 3-isopropyl-6-methyl-1H-benzo[f]indole-4,9-dione ( 3e ), N-(4-[isopentylamino]-3,6-dioxocyclohexa-1,4-dien-1-yl)acetamide ( 4d ), 2-(isopentylamino)-6-methylnaphthalene-1,4-dione ( 5b ), and 2-(4-acetamido-3,6-dioxocyclohexa-1,4-dien-1-yl)-N,N-diisopentyl-3-methylbutanamide ( 6a ) has been achieved via either pyrrol/aryl ring formations or amination reactions from the Pd(II)-catalyzed reaction of N-(3,6-dioxocyclohexa-1,4-dien-1-yl)acetamide ( 2a_BQ ) and in the presence of triisopentylamine. More 3 -, 4 -, 5 -, and 6 -like derivatives were obtained while other trialkylamines were used. Crystal structures of 3d_O , 3e , 4b , 4c , 4d , 5b, and 6a were determined by single-crystal X-ray diffraction methods. The 3 - and 5 -like products reveal the formations of newly generated benzene rings with/without substitutions. The formation of 6a also implies an unusual reaction pathway of its generation. Based on the structural conformations of various 3 -like products, as well as 6a , mechanisms were proposed to account for the formations of these compounds. Various fascinating conformations of products observed in this work demonstrate the diversities of this type of reactions.     

Intriguing generative metabolism discovery of reactive metabolite nitroso of lapatinib and relevant structural modification

Lapatinib is required as a therapy for advanced or metastatic breast cancer. However, its reactive metabolite (RM) nitroso was implicated in idiosyncratic hepatotoxicity. Density functional theory was performed to explore the metabolism of nitroso formation. Primary hydroxylation amine is a critical intermediate to produce nitroso. Three pathways from secondary alkylamine lapatinib to primary hydroxylation amine were designed and discussed. Calculation results show that it is difficult to form primary hydroxylation amine through common proposed hydrolysis nitrone with a barrier of 36.67 kcal/mol (path A), but it is smoothly formed by paths B and C with moderate determined barriers of 15.09 kcal/mol and 16.56 kcal/mol, respectively. Subsequently, we demonstrate that the mechanism of nitroso formation from primary hydroxylation amine should be a double hydrogen atom transfer rather than the previously proposed hydrolysis primary dihydroxylation amine. The barrier of the former is obviously lower than the latter. Based on metabolism results and structure analysis, several lapatinib derivatives are designed. Molecular docking of designed compounds with epidermal growth factor receptor (EGFR) shows that they share a similar binding mode with lapatinib. In particular, 2a to 2d show similar binding energy to lapatinib. This work showed metabolism details of nitroso formation from lapatinib and its structure modification, which can enrich the metabolism of amine drugs and provide guidance for drug optimization and design.     

2D sp2 Carbon‐Conjugated Porphyrin Covalent Organic Framework for Cooperative Photocatalysis with TEMPO

2D covalent organic frameworks (COFs) are receiving ongoing attention in semiconductor photocatalysis. Herein, we present a photocatalytic selective chemical transformation by combining sp² carbon‐conjugated porphyrin‐based covalent organic framework (Por‐sp²c‐COF) photocatalysis with TEMPO catalysis illuminated by 623 nm red light‐emitting diodes (LEDs). Highly selective conversion of amines into imines was swiftly afforded in minutes. Specifically, the π‐conjugation of porphyrin linker leads to extensive absorption of red light; the sp² ?C=C? double bonds linkage ensures the stability of Por‐sp²c‐COF under high concentrations of amine. Most importantly, we found that crystalline framework of Por‐sp²c‐COF is pivotal for cooperative photocatalysis with (2,2,6,6‐tetramethylpiperidin‐1‐yl)oxyl (TEMPO). This work foreshadows that the outstanding hallmarks of COFs, particularly crystallinity, could be exploited to address energy and environmental challenges by cooperative photocatalysis.