Synthesis and Characterization of a Low-Bandgap Poly(arylene ethynylene) Having Donor–Acceptor Type Chromophores in the Side Chain

Synthesis and Characterization of a Low-Bandgap Poly(arylene ethynylene) Having Donor–Acceptor Type Chromophores in the Side Chai

Dispersion Characteristics and Rheology of Organoclay Nanocomposites Based on a Segmented Main-Chain Liquid-Crystalline Polymer Having Pendent Pyridyl Group

The dispersion characteristics and rheology of organoclay nanocomposites based on a thermotropic liquid-crystalline polymer (TLCP) having pendent functional group were investigated using X-ray diffraction (XRD), transmission electron microscopy (TEM), and oscillatory shear rheometry. For the study, a segmented main-chain TLCP having pendent pyridyl group (PyHQ12) was synthesized and, for comparison, another segmented main-chain TLCP having pendent phenylsulfonyl group (PSHQ12) was synthesized, both TLCPs having the identical chemical structure for the main-chain backbone. The differences in phase transition temperature and rheological behavior observed between PyHQ12 and PSHQ12 are explained in terms of the self-associating characteristics of the pendent pyridyl group in PyHQ12. PyHQ12 and PSHQ12 were used to prepare nanocomposites with two commercial organoclays:  one (Cloisite 30B) was natural clay (montmorillonite) treated with a surfactant (MT2EtOH) having hydroxyl groups, and the other (Cloisite 20A) was montmorillonite treated with a surfactant (2M2HT) having no polar group. The following observations have been made. (i) PyHQ12/Cloisite 30B nanocomposite has featureless XRD patterns and a very high degree of dispersion of Cloisite 30B aggregates as determined from TEM. (ii) PyHQ12/Cloisite 20A nanocomposite has a conspicuous XRD reflection peak giving rise to an increase of gallery distance by 0.3 nm from the gallery distance of 3.1 nm for Cloisite 20A and intercalation of Cloisite 20A aggregates as determined from TEM. (iii) PSHQ12/Cloisite30B nanocomposite also has a conspicuous XRD reflection peak, giving rise to an increase of gallery distance by 0.2 nm from the gallery distance of 1.9 nm for Cloisite 30B and intercalation of Cloisite 30B aggregates as determined from TEM. The observed highly dispersed Cloisite 30B aggregates in PyHQ12/Cloisite 30B nanocomposite are attributed to the formation of hydrogen bonds, as determined by Fourier transform infrared spectroscopy, between the pendent pyridyl group in PyHQ12 and the hydroxyl groups in the surfactant MT2EtOH residing at the surface of Cloisite 30B. Oscillatory shear measurements of the three nanocomposites support the observations made from XRD and TEM

Ruthenium(II) Complex-Induced Dispersion of Montmorillonite in a Segmented Main-Chain Liquid-Crystalline Polymer Having Side-Chain Terpyridine Group

Ruthenium(II) Complex-Induced Dispersion of Montmorillonite in a Segmented Main-Chain Liquid-Crystalline Polymer Having Side-Chain Terpyridine Grou

Synthesis and Intramolecular Charge-Transfer Interactions of a Donor–Acceptor Type Polymer Containing Ferrocene and TCNAQ Moieties

Synthesis and Intramolecular Charge-Transfer Interactions of a Donor–Acceptor Type Polymer Containing Ferrocene and TCNAQ Moietie

High-Performance Nanopapers Based on Benzenesulfonic Functionalized Graphenes

High-performance graphene nanopapers are prepared from an aqueous solution of functional graphenes with benzenesulfonic acid groups <i>via</i> covalent bonds. The formed hydrophobic graphene nanopapers showed the highest tensile strength of 360 MPa and Young’s modulus of 102 GPa for samples with 13.7 wt % functional group and annealed at 150 °C. These samples showed a high electrical conductivity of 4.45 × 10⁴ S/m after being annealed at 250 °C. The aforementioned properties of graphene nanopapers are much higher than any previously reported data. The properties of nanopapers depend on the degree of functionality on graphenes and the annealing temperatures, which are further evidenced by X-ray photoelectron spectroscopy, FTIR, and X-ray diffraction patterns. Such unique nanopapers can be easily bounded and sandwiched onto any solid surface to give rise to great potentials in many applications such as gas diffusion barriers, EMI shielding, thermal management, and anticorrosion

Nickel-Catalyzed Carbonylation of Cyclopropanol with Benzyl Bromide for Multisubstituted Cyclopentenone Synthesis

Herein, we reported a Ni-catalyzed carbonylation of cyclopropanol with benzyl bromide to afford multisubstituted cyclopentenone under 1 atm of CO. The reaction proceeds through cascade carbonylation of benzyl bromides, followed by generation of nickel homoenolate from cyclopropanols via β-C elimination to afford 1,4-diketones, which undergoes intramolecular Aldol condensation to furnish highly substituted cyclopentenone derivatives in moderate to good yields. The reaction exhibits high functional group tolerance with broad substrate scope

Nickel-Catalyzed Formal Aminocarbonylation of Unactivated Alkyl Iodides with Isocyanides

Herein, we disclose a Ni-catalyzed formal aminocarbonylation of primary and secondary unactivated aliphatic iodides with isocyanides to afford alkyl amide, which proceeds via the selective monomigratory insertion of isocyanides with alkyl iodides, subsequent β-hydride elimination, and hydrolysis process. The reaction features wide functional group tolerance under mild conditions. Additionally, the selective, one-pot hydrolysis of reaction mixture under acid conditions allows for expedient synthesis of the corresponding alkyl carboxylic acid

Nickel-Catalyzed Formal Aminocarbonylation of Unactivated Alkyl Iodides with Isocyanides

Herein, we disclose a Ni-catalyzed formal aminocarbonylation of primary and secondary unactivated aliphatic iodides with isocyanides to afford alkyl amide, which proceeds via the selective monomigratory insertion of isocyanides with alkyl iodides, subsequent β-hydride elimination, and hydrolysis process. The reaction features wide functional group tolerance under mild conditions. Additionally, the selective, one-pot hydrolysis of reaction mixture under acid conditions allows for expedient synthesis of the corresponding alkyl carboxylic acid

Direct Transformation of Aryl 2‑Pyridyl Esters to Secondary Benzylic Alcohols by Nickel Relay Catalysis

A direct transformation of aryl esters to secondary benzylic alcohols via tandem Ni-catalyzed cross-coupling reactions of aromatic 2-pyridyl esters with alkyl zinc reagents and carbonyl group reduction by Ni–H species is achieved. Preliminary mechanistic studies reveal that the Ni–H species is generated in situ via β-hydride elimination of the Negishi reagents. The reaction is catalyzed by bench-stable nickel salts under mild conditions with wide functional group tolerance