Nonlinear optical properties, synthesis, structures and spectroscopic studies of N-(4-nitrobenzylidene)-o-fluoroamine and N-(3-nitrobenzylidene)-p-fluoroamine

N-(4-nitrobenzylidene)-o-fluoroamine (1) and N-(3-nitrobenzylidene)-p-fluoroamine (2) have been synthesized. The crystal structures of both compounds have been defined by X-ray diffraction analysis, and characterized by FT-IR and UV-visible instrumental methods. The recorded spectrum by UV-visible spectroscopy for the investigated compounds show good transparency in the visible region, and have solvatochromic behavior in the UV region, implying nonzero microscopic first hyperpolarizability. We also report ab initio quantum chemical calculations of the electric dipole moments (mu) and the first hyperpolarizabilities (beta) of the studied compounds. Our results suggest that the investigated ligands might have microscopic nonlinear optical (NLO) behavior with nonzero values.     

Poly(styrene‐b‐tetrahydrofuran)/clay nanocomposites by mechanistic transformation

Synthesis of poly(styrene‐block‐tetrahydrofuran) (PSt‐b‐PTHF) block copolymer on the surfaces of intercalated and exfoliated silicate (clay) layers by mechanistic transformation was described. First, the polystyrene/montmorillonite (PSt/MMT) nanocomposite was synthesized by in situ atom transfer radical polymerization (ATRP) from initiator moieties immobilized within the silicate galleries of the clay particles. Transmission electron microscopy (TEM) analysis showed the existence of both intercalated and exfoliated structures in the nanocomposite. Then, the PSt‐b‐PTHF/MMT nanocomposite was prepared by mechanistic transformation from ATRP to cationic ring opening polymerization (CROP). The TGA thermogram of the PSt‐b‐PTHF/MMT nanocomposite has two decomposition stages corresponding to PTHF and PSt segments. All nanocomposites exhibit enhanced thermal stabilities compared with the virgin polymer segments. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 2190–2197, 2009     

Some Remarks Concerning Hyperholomorphic B-Manifolds

The authors consider a differentiable manifold with H-structure which is an isomorphic representation of an associative, commutative and unitial algebra. For Riemannian metric tensor fields, the φ-operators associated with r-regular H-structure are introduced. With the help of φ-operators, the hyperholomorphity condition of B-manifolds is established.     

On coupled problems in geomechanics

Geomechanical problems are generally based on the category of granular, cohesive-frictional materials with a fluid pore content. At the macroscopic scale of continuum mechanics, these materials can be successfully described on the basis of the well-founded Theory of Porous Media (TPM) [1]. The present contribution touches fundamental problems of coupled media by investigating the interacting behaviour of an elasto-viscoplastic porous solid skeleton, the soil, and two pore fluids, water and air. Furthermore, electro-chemical reactions are considered in order to include the swelling behaviour of active soil. In conclusion, this leads to a system of strongly coupled partial differential equations (PDE) that can be solved by use of the finite element method (FEM). In particular, the presentation includes fluid-flow situations in the fully or the partially saturated range, swelling phenomena of active clay [3] as well as localisation phenomena [2] as a result of fluid flow or heavy rainfall events. The computations are carried out by use of the single-processor FE tool PANDAS [4] and, in case of large 3-d problems, by coupling PANDAS with the multi-processor solver M++. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)     

[N,N′‐Bis(5‐bromo­salicyl­idene)‐o‐phenylene­diaminato]copper(II)

In the title compound, {4,4′‐di­bromo‐2,2′‐[o‐phenyl­ene­bis­(nitrilo­methyl­idene)]­di­phen­ol­ato‐O,N,N′,O′}copper(II), [Cu(C₂₀H₁₂Br₂N₂O₂], the Cu^II ion shows a slightly distorted square‐planar geometry with the N₂O₂ atoms of the Schiff base imine–phenol tetradentate ligand.     

Development of a donor-acceptor concept for enzymatic cross-coupling reactions of aldehydes: the first asymmetric cross-benzoin condensation

Highly enantioenriched mixed benzoins are obtained selectively through a biocatalytical cross-coupling reaction of aromatic aldehydes using ThDP-dependent enzymes.     

Reinvestigation of the synthetic and mechanistic aspects of Mn(III) acetate mediated oxidation of enones

Mn(OAc)₃ mediated α′-acetoxylation of α,β-unsaturated enones is reinvestigated from a synthetic and mechanistic point of view and an improved procedure based on the use of acetic acid as a co-solvent is presented. Excellent results were obtained for a variety of structurally diverse and synthetically important enones under the optimized conditions.     

Electronic,optical, and charge transfer properties of porphyrin and metallated porphyrins in different media

Porphyrin and M-Porphyrin (M = Fe²⁺, Co²⁺, Ni²⁺, Cu²⁺, and Zn²⁺) complexes were designed to examine their organic light-emitting diode (OLED) properties. All calculations were performed in different media, which are gas, benzene, DMSO, and water phases. The calculations of both porphyrin and its metal complexes as a monomer form were performed at B3LYP/6-31G(d) level by using the Gaussian 16 and GaussView 6 package programs. On the other hand, emission calculations for the monomer form and dimer form computations of the studied compounds were carried out at PBE0/TZP and B3LYP/TZP levels, respectively, by using Amsterdam density functional (ADF) 2019 package program. The OLED tensors of the mentioned molecules, which are emission energies, reorganization energies (λ_e and λ_h), the ionization potentials and the electron affinities (adiabatic and vertical), the effective transfer integrals (V_e and V_h), and the charge transfer rates (W_e and W_h), were calculated to evaluate the OLED behaviors and determine the best OLED structure.     

Preparation and characterization of hexagonal boron nitride and PAMPS-NMPA-based thin composite films and investigation of their membrane properties

The preparation, thermal, morphological, and ion-conducting properties of new composite membranes based on poly(2-acrylamido-2-methyl-1-propanesulfonic acid) (PAMPS) and nitrilotri(methylphosphonic acid) (NMPA)/hexagonal boron nitride (hBN) were carried out throughout this work. Fourier transform infrared (FTIR) spectroscopy was used to characterize the interactions between host polymer, NMPA, and inorganic additive, hBN. Thermal properties of the materials were examined by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) tests. TGA results illustrated that all composite membranes are thermally stable up to 200 °C. The surface topography of the films was investigated by scanning electron microscopy (SEM) and verified that hBN uniformly dispersed into the PAMPS-NMPA matrix. The crystallinity of the membranes was characterized by using X-ray diffraction (XRD). X-ray patterns support semicrystalline nature of the composite materials. At anhydrous conditions, the maximum proton conductivity was found as 3.2?×?10^?5 S cm^?1 at 150 °C for PAMPS-NMPA-3hBN via impedance analyzer.     

An Efficient Synthesis of Substituted 2H-Pyran-2-one Derivatives via the Conjugated Addition of the Enolates of Carbonyl Compounds to Enaminoesters

Short simple synthesis of alkenoic acid esters and their intramolecular cyclization products, 2H-Pyran-2-ones from enolates of carbonyl compounds and enaminoesters are described.