Darstellung und Struktur von Pyrazolyl-Kationen mit Polymethin- und Methan-Gerüst

The 4-pyrazoline-3-one1 reacts with 4-dimethylaminobenzaldehyde to yield the stable asymmetric cyanine dye2b which reacts with1 to give the colorless (aryl) (dipyrazolyl) methane3b. Using aldehydes with less cationstabilizing groups the polymethines2 are not isolated but only the methanes3. The structures of2b and3 are discussed by¹ H,¹³C and Hetero NMR spectra.     

Reaction of electron rich heterocycles with electrophiles. Formylation of indoles via thiomethylation

The formylation of indoles 1 by dithiocarbenium-ions 2 is discussed. The reaction proceeds to thioacetals 4 under mild conditions. Longer reaction times yield bisindolylmonomethylcyanines 5–6 . Generally, the reaction is inhibited by the presence of electron-withdrawing groups at the pyrrol nucleus of indole 1 , e.g. an acetyl group.     

Structural and optical properties of ZnO thin films by the spin coating Sol-Gel method

ZnO thin films were deposited onto glass subsrates by a Sol-gel spin coating method. The structural and optical properties of ZnO thin films were investigated. The molar ratios of the zinc acetate dihydrate to Monoethanolamine were maintained 1:1. The as-grown film was sintered 250 °C for 10 min, then annealed in air at 500 °C for 30 min. The XRD results indicate that ZnO films were strongly oriented to the c-axis of the hexagonal nature. Absorption measurements were carried out as a function of temperature with 10 K steps in the range 10–320 K. The band gap energy was measured 3.275 and 3.267 eV for 0.5 and 1.0 molarity (M) ZnO thin films at 300 K. The steepness parameters were observed between 10 and 320 K and their extrapolations converged at (E₀, α₀) = 3.65 eV, 172,819 cm⁻¹ and 3.70 eV, 653,436 cm⁻¹ for 0.5 and 1.0 M ZnO thin films, respectively.     

Theoretical investigation of excited states of oligothiophene anions

Electron-hole symmetry upon p- and n-doping of conducting organic polymers is rationalized with Hückel theory by the presence of symmetrically located intragap states. Since density functional theory (DFT) predicts very different geometries and energy level diagrams for conjugated pi-systems than semiempirical methods, it is an interesting question whether DFT confirms the existence of electron-hole symmetry predicted at the Hückel level. To answer this question, geometries of oligothiophene anions with 5-19 rings were optimized and their UV/vis spectra were calculated with time-dependent DFT. Although DFT does not produce symmetrically placed sub-band energy levels, spectra of cations and anions are almost identical. The similarity in transition energies and oscillator strengths of anions and cations can be explained by the fact that the single sub-band energy level of cations lies above the valence band by the same amount of energy as the single sub-band level of anions lies below the conduction band. This and the resemblance of the energy level spacings in valence bands of cations to those in conduction bands of anions give rise to peaks with equal energies and oscillator strengths.     

Analysis of the bond‐valence method for calculating 29Si and 31P magnetic shielding in covalent network solids

²⁹Si and ³¹P magnetic‐shielding tensors in covalent network solids have been evaluated using periodic and cluster‐based calculations. The cluster‐based computational methodology employs pseudoatoms to reduce the net charge (resulting from missing co‐ordination on the terminal atoms) through valence modification of terminal atoms using bond‐valence theory (VMTA/BV). The magnetic‐shielding tensors computed with the VMTA/BV method are compared to magnetic‐shielding tensors determined with the periodic GIPAW approach. The cluster‐based all‐electron calculations agree with experiment better than the GIPAW calculations, particularly for predicting absolute magnetic shielding and for predicting chemical shifts. The performance of the DFT functionals CA‐PZ, PW91, PBE, rPBE, PBEsol, WC, and PBE0 are assessed for the prediction of ²⁹Si and ³¹P magnetic‐shielding constants. Calculations using the hybrid functional PBE0, in combination with the VMTA/BV approach, result in excellent agreement with experiment. © 2016 Wiley Periodicals, Inc.     

The relationship between almost Dunford-Pettis operators and almost limited operators

We investigate Banach lattices on which each positive almost Dunford- Pettis operator is almost limited and conversely.     

Investigation of structural and optical properties of ZnO films co-doped with fluorine and indium

Undoped ZnO film and ZnO films, which are co-doped with F and In (FIZO) at different concentrations, were synthesized by sol–gel technique and the effects of co-doping of F and In on structural and optical properties of ZnO thin films were investigated. The concentration ratio of [F]/[Zn] was altered from 0.25 to 1.75 with 0.50 step at.% mole and [In]/[Zn] was altered from 0.25 to 1.00 with 0.25 step at.% mole. X-ray diffraction analysis indicates that the films have polycrystalline nature and the (0 0 2) preferred orientation is the stronger peak. No extra phases involving zinc, fluorine and indium compounds were observed even at high F and In content. The grain size of undoped ZnO and FIZO thin films varied between 15 and 20 nm with a small fluctuation. From the SEM images, although the undoped ZnO had a smooth and particle-shaped surface, FIZO films had nanofiber-networks shapes over the surface with average size of 500 nm. The surface morphologies and crystallite sizes for the F and In doped films were slightly different from than those of undoped film. From the optical study, a slight shrinkage of band gap was backwardly observed from 3.36 to 3.25 eV with the increasing of F and In content.     

A note on Tang and He’s paper

In this paper, we establish new Lyapunov-type inequalities for two classes of one-dimensional quasilinear elliptic systems of resonant type, which improve the recent results of Tang and He [X.H. Tang, X. He, Lower bounds for generalized eigenvalues of the quasilinear systems, J. Math. Anal. Appl. 385 (2012) 72-85] when 1 < p_i < 2 for i = 1, 2, … , n.     

Zur Reaktion von Phenazon und lithiiertem Phenazon mit Aryl-Carbonyl-Derivaten

Some new experimental results are described on the acid catalysed reaction of the 4-Pyrazoline-3-on (1a) with aromatic aldehydes leading to the cationic derivatives4 and5.4-Pyrazoline-3-on-lithium (1b), synthesised for the first time, gives in good yield with 4-dimethylaminobenzaldehyde under mild condition the cyanine2b and with benzophenone the pyrazolyl-diphenylmethane dye8.

Zur Struktur von2a und4a siehe Lit.².