Partially bio‐based poly(amide imide)s by polycondensation of aromatic diacylhydrazides based on lignin‐derived phenolic acids and aromatic dianhydrides: Synthesis,characterization, and computational studies

Two new bio‐based diacylhydrazide monomers, namely, 4,4′‐(propane‐1,3‐diylbis(oxy))bis(3‐methoxybenzohydrazide) and 4,4′‐(propane‐1,3‐diylbis(oxy))bis(3,5‐dimethoxybenzohydrazide) were synthesized starting from lignin‐derived phenolic acids, namely, vanillic acid and syringic acid. A series of poly(amide imide)s was synthesized by polycondensation of these diacylhydrazide monomers with commercially available aromatic dianhydrides. Poly(amide imide)s showed inherent viscosity in the range 0.44–0.56 dL g^?1 and exhibited good solubility in organic solvents. Poly(amide imide)s could be cast into transparent, flexible, and tough films from their N ,N‐dimethylacetamide solutions. Poly(amide imide)s showed 10% weight loss in the temperature range 340–364 °C indicating their good thermal stability. Glass transition temperature (T _g) of poly(amide imides)s were measured by DSC and DMA which were in the range 201–223 °C and 214–248 °C, respectively. The T _g values of poly(amide imide)s were dependent on the number methoxy substituents on aromatic rings of diacylhydrazide monomers. Molecular dynamics simulation studies revealed that chain rigidity is the dominant factor for observed trends in T _g. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55 , 3636–3645     

Preparation of Functionalized Diaryl‐ and Diheteroaryllanthanum Reagents by Fast Halogen–Lanthanum Exchange

Aryl and heteroaryl halides (X=Br, I) undergo a fast and convenient halogen–lanthanum exchange with nBu₂LaMe, which leads to functionalized diaryl‐ and diheteroaryllanthanum derivatives. Subsequent trapping reactions with selected electrophiles, such as ketones, aldehydes, or amides, proceeded smoothly at −50 °C in THF, affording polyfunctionalized alcohols and carbonyl derivatives. Kinetic competition experiments revealed a similar reactivity trend as for Br/Mg exchange, but 10⁶‐times higher rates, making it comparable to Br/Li exchange.     

Probing the material properties and phase transitions of ferroelectric liquid crystals by determination of the Landau potential

The full Landau potential of several, widely varying ferroelectric liquid-crystalline materials has been experimentally determined. Tilt angle and polarisation data is analysed across the SmA to SmC transition for varying applied electric-field amplitudes, allowing the determination of all the coefficients of the generalised Landau model of ferroelectric liquid crystals. The materials investigated encompass different materials, including low-polarisation mixtures to high-polarisation single-component materials. The materials also possess a variation in the order of the SmA to SmC phase transition from strongly first order to strongly second order. The effects of both the polarisation and order of phase transition of the system are discussed with respect to the various terms of the generalised Landau model. Further, the mechanisms behind the difference between a first- and second-order phase transition are discussed with respect to the Landau potential and the second Landau coefficient b .     

三峡库区典型塌岸模式研究

三峡库区塌岸地质条件调查结果表明,不同的岸坡结构,蓄水后库岸的变形破坏形式—塌岸模式,往往差别较大。本文根据现场调查成果,结合室内分析,总结归纳出三峡库区几种典型的塌岸模式,即冲蚀磨蚀型、坍塌型、崩塌(落)型、、滑移型和流土型。在此基础上,对不同塌岸模式的发展演进过程、发育分布特征,以及塌岸与岸坡岩土结构、地形地貌等的关系进行了深入系统地研究,提出了三峡库区典型塌岸发育的一般地质条件。     

Structural characterization,thermal investigation and biological activity of metal complexes containing Schiff Base ligand (Z)‐3‐(1‐((4,6‐dimethyl‐1H‐pyrazolo[3,4‐b] pyridin‐3‐yl)imino)ethyl)‐4‐hydroxy‐6‐methyl‐2H‐pyran‐2‐one

A new series of metal complexes containing Co(II), Pd(II), Fe(III) chloride and Cu(II) salts (chloride, bromide, sulphate and perchlorate) have been prepared with Schiff base ligand ( HL ). The synthesized compounds were elucidated using elemental analyses, spectral techniques, molar conductance, magnetic measurements and thermogravimetric studies. The analytical data established (1 M:1 L) stoichiometry for complexes ( 1 ), ( 2 ), ( 4 ), ( 6 ) and ( 7 ) as well as (1 M:2 L) and (2 M:3 L) stoichiometry for complexes ( 5 ) and ( 3 ), respectively. As a result, the ligand HL coordinates in complexes ( 1 ), ( 2 ), ( 4 ), ( 6 ) as a monobasic tridentate ONN moiety via the oxygen atom of the deprotonated phenolic OH, the nitrogen atoms of the azomethine and the imine group in pyrazolopyridine ring. While, it behaves as a neutral bidentate in complexes ( 3 , 7 ), chelates via oxygen and nitrogen atoms of enolic OH and azomethine groups. Also, in complex ( 5 ) Cu²⁺ ion binds via NO sits of two ligand molecules in its monobasic and neutral forms. The magnetic moment and electronic spectral data proposed octahedral structure for complexes ( 2 , 3 and 7 ) as well as triagonal bipyramidal and square pyramidal geometry for complexes ( 1 and 4 ), while, chelates ( 5 ) and ( 6 ) possess square planar geometry. TG/DTG studies confirmed the chemical formula for these complexes and established the thermal decomposition processes ended with the formation of metal or metal oxides contaminated with carbon residue. An axial electron spin resonance spectra were suggested for Cu(II) complexes pointing to ²B_1g as a ground state with hyperfine structure for complex ( 4 ). In vitro antibacterial and antioxidant activities were performed for HL ligand and its metal complexes. The biological studies indicate that complex ( 3 ) has better antibacterial activity compared to the ligand and the other complexes.     

Transition metal complexes of nano bidentate organometallic Schiff base: Preparation,structure characterization,biological activity,DFT and molecular docking studies

An organometallic NO‐bidentate Schiff base, (2‐(1‐((1‐carboxyethyl)imino)ethyl) cyclopenta‐2,4‐dien‐1‐yl)(cyclopenta‐2,4‐dien‐1‐yl) iron (HL) was synthesized by condensation of 2‐acetylferrocene with amino acid alanine. Then its octahedral Cr (III), Mn (II), Fe (III), Co (II), Ni (II), Cu (II), Zn (II) and Cd (II) complexes were synthesized. All compounds were characterized on the basis of elemental analysis (C, H, N and M), molar conductivity, FT‐IR, UV–Vis, ¹H‐NMR, SEM, mass analysis and thermal studies. Furthermore, computational studies of HL ligand have been carried out by DFT/B3LYP method. HOMO and LUMO energy values, chemical hardness‐softness, electronegativity, electrophilic index and other parameters were calculated. SEM micrographs of HL ligand and its [Cd (HL)(H₂O)₂Cl₂].2H₂O complex, showed that they were prepared in nano‐structure forms with particle size 54 and 41 nm, respectively. Antifungal and antibacterial activities of HL ligand and its metal complexes have been screened in vitro against different species such as Aspergillus fumigatus, Candida albicans, Bacillus subtilis, Staphylococcus aureus, Escherichia coli and Salmonella typhimurium. The synthesized compounds were evaluated for their anticancer activities against breast cancer cell line (MCF‐7) and normal melanocytes cell line (HFB‐4). It was found that [Co (HL)(H₂O)₂Cl₂].3H₂O complex had the lowest IC₅₀ value (10.9 μg/ml) and hence was the most active one. Finally, the optimized structures of the Schiff base and its Co (II) complex have been used to accomplish molecular docking studies with receptors of 3HB5, 3MIW, 5IBV and 4WM8 to determine the most preferred mode of interaction.     

Synthesis,spectra, crystal structures and anticancer studies of 26‐membered macrocyclic dibutyltin(IV) dithiocarbamate complexes: Single‐source precursors for tin sulfide nanoparticles

Four new macrocyclic dinuclear dibutyltin(IV) dithiocarbamate complexes of the type [Bu₂Sn(dtc)]₂, where dtc = hexane‐1,6‐diylbis(4‐fluorobenzyldithiocarbamate) anion ( 1 ), hexane‐1,6‐diylbis(4‐chlorobenzyldithiocarbamate) anion ( 2 ), hexane‐1,6‐diylbis(furfuryldithiocarbamate) anion ( 3 ) and hexane‐1,6‐diylbis(pyrrole‐2‐ylmethyldithiocarbamate) anion ( 4 ), have been prepared. The dithiocarbamate ligands efficiently self‐assemble with Bu₂Sn(IV) to form bimetallic 26‐membered macrocycles. All the complexes have been characterized using elemental analysis, infrared and NMR (¹H and ¹³C) spectroscopies and X‐ray crystallography. Single‐crystal X‐ray diffraction analysis of all the complexes confirms the formation of the dinuclear metallomacrocycles in which dithiocarbamate ligands are asymmetrically bound to the tin atoms. The coordination sphere around the tin atom in 1 – 4 can be described as a skew trapezoidal bipyramid. The dimensions of the cavity of the macrocycles of 1 – 4 are ca 8.0 × 9.0 Å². Complexes 1 – 4 were evaluated for their in vitro anticancer activity against MCF‐7 and HL‐60 cells. Complexes 1 and 2 are more active against MCF‐7 and HL‐60. Thermal decomposition of 1 and 4 yielded tin sulfides. They were characterized using powder X‐ray diffraction (PXRD), high‐resolution transmission electron microscopy and UV diffuse reflectance and energy‐dispersive X‐ray spectroscopies. PXRD studies reveal that the as‐prepared tin sulfides are composed of orthorhombic phase of SnS.     

Time-Resolved Chemically Induced Dynamic Nuclear Polarization of Biologically Important Molecules

In this work, we review the hyperpolarization technique named chemically induced dynamic nuclear polarization (CIDNP), focusing on the time-resolved variant of this method and its biological applications. We introduce the main principles of polarization formation in liquids at high magnetic fields, provided by the so-called spin sorting mechanism. Applications of CIDNP to studying fast reactions of short-lived free radicals of biologically important molecules are discussed, as well as the potential of the method to probe the structure and magnetic parameters of such radicals. We also explain the principles of protein CIDNP and discuss applications of time-resolved CIDNP to studies of protein structure and dynamics.     

Spectroscopic studies on the interaction of alpha‐eleostearic acid with calf thymus DNA

Interaction between alpha‐eleostearic acid (α‐ESA) and calf thymus DNA in Tris‐HCl buffer (pH = 7.4) using neutral red (NR) dye as a spectral probe was investigated using UV–Vis absorption and fluorescence spectroscopy. Spectral data matrix of the complexed reaction between α‐ESA and NR with DNA was processed with an alternative least‐squares (ALS) algorithm, the obtained concentration profiles and the corresponding pure spectra for species (NR, DNA–NR, and DNA–NR–ESA) demonstrated three kinds of reactions might occur in the system. The major groove binding between α‐ESA and DNA was further validated using circular dichroism, viscosity, DNA melting, and ionic strength effect measurements. Moreover, the calculated values of thermodynamic parameters, such as enthalpy (ΔH^θ, ?22.04 kJ/mol) and entropy change (ΔS^θ, 91.52 J K^?1 mol^?1), suggested binding between α‐ESA and DNA was mainly driven by hydrophobic interactions and hydrogen bonds without electrostatic force.     

Enhancement of mechanical and barrier properties of LLDPE composite film via PET fiber incorporation for agricultural application

A study was conducted to determine the potential of linear low‐density polyethylene (LLDPE)‐PET fiber composite films to be used as an agricultural mulching film. Incorporation of 1 wt% PET fiber into the LLDPE matrix improved the tensile strength and percent elongation. The water vapor transmission rate was significantly lowered because of the presence of PET fibers. Also, the effect of continuous exposure of films to pesticide and UV light has been reported in terms of deterioration of mechanical and optical properties of the films. Differential scanning calorimetry shows that there is no effect of the presence of PET fibers on processing temperature of LLDPE at optimized loading; however, it was found that it lowers the latent heat of fusion and crystallization.