Synthesis of crown ethers bearing 2,4‐dinitrophenylhydrazone

The o‐dihydroxy‐ ( 2a‐b ), dimethoxy ( 3a‐b ), ethylendioxy‐ ( 4a‐b ) and macrocyclic polyethers ( 4c‐i ) are the initial compounds while the 2,4‐dinitrophenylhydrazone compounds ( 5a‐d, 6a‐i ) represent new derivatives. Novel hydrazone compounds were synthesized from the corresponding cyclic ketones ( 4a‐i ) and 2,4‐dinitrophenylhydrazine in H₂SO₄/EtOH/H₂O solution at room temperature for 1 h. The structures of obtained hydrazone compounds were confirmed by ¹H‐NMR, ¹³C‐NMR, EI‐MS, IR spectra and elemental analysis.     

Optical characterization and crystal structure of the novel bronzetype CaxBa1‐xNb2O6 (x = 0.28; CBN‐28)

Calcium barium niobate (CBN), also like strontium barium niobate (SBN), belongs to the materials family of partially filled tetragonal tungsten bronzes, which show relaxor‐type ferroelectric phase transitions and large electro‐optic effects. For the first time, it was possible to grow large single crystals of Ca_0.25Ba_0.75Nb₂O₆ (CBN‐25) and CBN‐28 by using different growing techniques. The successful single crystal growth allowed to investigate several physical properties of the novel phase. Herein, we report on measurements of differential thermal analysis (DTA), wavelength dispersion of the refractive indices, temperature dependence of the birefringence and light absorption. Additionally, results of the single crystal X‐ray structure analysis are presented.     

trans‐Bis­[N‐(2‐hydroxy­ethyl)­ethyl­ene­di­amine‐κ2N,N′]­bis­(iso­thio­cyanato‐κN)­nickel(II)

The crystal structure of the title compound, [Ni(NCS)₂(C₄H₁₂N₂O)₂], has two crystallographically independent half‐mol­ecules in the asymmetric unit, with each Ni atom residing on a centre of symmetry. The two mol­ecules exhibit similar coordination geometry but display differences with regard to other structural features. Each Ni^II centre is octahedrally coordinated by two mutually trans chelating hydroxy­ethyl­ethyl­ene­di­amine ligands and two mutually trans iso­thio­cyanate ions. The two independent mol­ecules form chains through different types of non‐covalent interactions. In the case of one of the mol­ecules, only NCS and free OH groups participate in hydrogen bonding, while in the chain based on the second mol­ecule, the NCS, NH, NH₂ and free OH groups are involved in intermolecular hydrogen bonding. The two chains interact with one another through hydrogen bonding, forming planar sheets. The third packing direction is mediated only by van der Waals interactions.     

Bis(1,10‐phenanthroline‐κ2N,N′)(squarato‐κO)copper(II) trihydrate

The title mononuclear [Cu(sq)(phen)₂]·3H₂O complex [sq is squarate (C₄O₄) and phen is 1,10‐phenanthroline (C₁₂H₈N₂)] has been synthesized and the structure consists of a neutral mononuclear [Cu(sq)(phen)₂] unit and three solvate water mol­ecules. The Cu^II ion has distorted square‐pyramidal coordination geometry, comprised of one carboxyl­ate O atom from a monodentate squarate ligand and four N atoms from two chelating phen ligands. An extensive three‐dimensional network of OW—H⋯O/OW hydrogen bonds, face‐to‐face π–­π interactions between the 1,10‐phenanthroline aromatic rings and a weak π–ring interaction are responsible for crystal stabilization.     

The generalization of the generalized Al-Oboudi differential operator

In this paper, firstly we define the generalization of the generalized Al-Oboudi differential operator. Then we also define new classes of analytic and p-valently starlike and convex functions with complex order by means of this new general differential operator. Our main purpose is to determine coefficient bounds for functions in certain subclasses of this classes, which are introduced here by means of a family of nonhomogeneous Cauchy-Euler differential equations. Relevant connections of some of the results obtained with those in earlier works are also provided.     

Optical solitons and other solutions to the conformable space–time fractional complex Ginzburg–Landau equation under Kerr law nonlinearity

This study reveals the dark, bright, combined dark–bright, singular, combined singular optical solitons and singular periodic solutions to the conformable space–time fractional complex Ginzburg–Landau equation. We reach such solutions via the powerful extended sinh-Gordon equation expansion method (ShGEEM). Constraint conditions that guarantee the existence of valid solitary wave solutions are given. Under suitable choice of the parameter values, interesting three-dimensional graphs of some of the obtained solutions are plotted.     

Physical properties of the cubic spinel LiMn2O4

We have performed an ab initio study of structural, electronic, magnetic, vibrational and thermal properties of the cubic spinel LiMn₂O₄ by employing the density functional theory, the linear-response formalism, and the plane-wave pseudopotential method. An analysis of the electronic structure with the help of electronic density of states shows that the density of states at the Fermi level (N (E_F)) is found to be governed by the Mn 3d electrons with some contributions from the 2p states of O atoms. It is important to note that the contribution of Mn 3d states to N(_EF)$N\left(E_F\right)$ is as much as 85%. From our phonon calculations, we have obtained that the main contribution to phonon density of states (below 250 cm⁻¹) comes from the coupled motion of Mn and O atoms while phonon modes between 250 cm⁻¹ and 375 cm⁻¹ are characterized by the vibrations of all the three types of atoms. The contribution from Li increases rapidly at higher frequency (above 375 cm⁻¹) due to the light mass of this atom. Finally, the specific heat and the Debye temperature at 300 K are calculated to be 249.29 J/mol K and 820.80 K respectively.     

Dynamic stability analysis of torsional vibrations of a shaft system connected by a Hooke׳s joint through a continuous system model

Stability of parametrically excited torsional vibrations of a shaft system composed of two torsionally elastic shafts interconnected through a Hooke?s joint is studied. The shafts are considered to be continuous (distributed-parameter) systems and an approximate discrete model for the torsional vibrations of the shaft system is derived via a finite element scheme. The stability of the solutions of the linearized equations of motion, consisting of a set of Mathieu–Hill type equations, is examined by means of a monodromy matrix method and the results are presented in the form of a Strutt–Ince diagram visualizing the effects of the system parameters on the stability of the shaft system.