Search results for " Crystal"

Spectroscopic studies and crystal structure of bis(N-2-pyridinylcarbonyl-2-pyridinecarboximidato) manganese(II) monohydrate: Zero-field splitting par…

1990

Abstract The X-ray crystal structure of bis(N-2-pyridinylcarbonyl-2-pyridinecarboximidato)manganese(II) monohydrate, Mn(BPCA)2·H2O, has been determine

An Unusual Geometry of Five-Coordinate Copper(II): The Structure of Cu(terpy)I2 and Spectroscopic Investigations of Complexes Cu(terpy)X2 (X: I, NCS)

1991

The structure of the compound Cu(terpy)I2 (terpy 2,2′: 6′, 2″ terpyridine) was determined at room temperature. It is monoclinic, space group I2/c with a = 13.689(3), b = 9.510(2), c = 11.605(3) Å, β = 97.59(4)° and Ζ = 4. The copper(II) ions are five-coordinated by the three nitrogen atoms from the terpy ligand and the two iodine atoms. The CuN3I2 polyhedron exhibits the same unusual “reverse” geometry as is observed for Cu(terpy)(NCS)2. Single crystal EPR measurements of the iodide and the isothio-cyanate complexes confirmed the structural results, excluding the possibility of a dynamically averaged geometry.

Synthesis and Characterization of a New Fully Aromatic LCP

1996

Abstract Liquid crystal polymers (LCP)are a relatively new class of polymers with very interesting and unusual properties. In particular, easy processability and outstanding mechanical and barrier properties make them very attractive. Unfortunately the high stiffness of their chains often leads to compounds having very high melting points and consequently to unprocessable materials. By adding a flexible segments in the chain backbone the LCPs become processable at lower temperatures but lower properties are displayed. A new rigid liquid crystalline polymer, having excellent physical properties, good processing temperature and a good cost/performance compromise, is described in this work. Th…

A Co-monosubstituted Keggin polyoxometalate with an antenna ligand and three cobalt(II) chains as counterion

2009

Abstract A Co-monosubstituted Keggin polyoxometalate with an antenna ligand linked to the Co(II) center with a Co(II)-containing cation has been prepared. The title compound, formulated as {Co(H 2 O) 4 (4,4′-bpy)} 2 (4,4′-Hbpy) 2 [SiW 11 Co(4,4′-bpy)O 39 ] · 5H 2 O ( 1 ) (4,4′-bpy = 4,4′-bipyridine), was synthesized and characterized by elemental analysis, IR spectra, TG analysis, X-ray single crystal structure analysis and magnetic measurements. As far as we know, the title compound represents the first Co(II) substituted Keggin polyoxometalate with an antenna ligand structurally and magnetically characterized.

Efficient Diffusion-Controlled Ligand Exchange Crystal Growth of Isostructural Inorganic–Organic Halogenidorhodates(III): The Missing Hexaiodidorhoda…

2015

The monohydrates of piperazine-1,4-diium hexabromidorhodate(III) bromide and hexaiodidorhodate(III) iodide were obtained by a diffusion-controlled ligand exchange crystal growth method using a hydrochloric acid solution of rhodium(III) chloride trihydrate and piperazine, dissolved in hydrobromic and hydroiodic acid, respectively, separated by a layer of hydrohalic acid. Both inorganic–organic hybrids are defined by the general formula (C4H12N2)2[RhX6]X·H2O (X = Br, 1 or I, 2). They both crystallize in the orthorhombic Pnma space group, and they are isostructural with an isostructurality index above 95%. The cationic building blocks—piperazine-1,4-diium ions and the inorganic components—slig…

Synthesis and X-Ray Single Crystal Structure of Two New Copper Complexes with the Redox Active Ligand 1,10-Phenanthroline-5,6-dione

2005

The synthesis and the crystal structures of the complexes [Cu(LI)2](ClO4) (1) and [Cu(LI)(CH3CN)2(ClO4)2] (2) are reported. 1 crystallizes in the monoclinic space group C2/c with the unit cell dimensions a = 13.169(4), b = 12.289(3), c = 14.732(3) A, β = 109.03(2)° and Z = 4. Copper(I) is coordinated to four N atoms of the two 1,10-Phenanthroline-5,6-dione (LI) ligands with a two-fold axis passing between the ligands. The copper(II) compound 2 crystallizes in the orthorhombic space group Pbn21 with unit cell dimensions of a = 7.498(5), b = 23.492(7), c = 12.363(4) A and Z = 4. Copper(II) coordination can be described as a distorted octahedron with the N donor atoms of one LI ligand and of t…

Influence of Cl/Br substitution on the stereochemical peculiarities of copper(I) pi-complexes with the 1-allyl-2-aminopyridinium cation.

2003

By using alternating-current electrochemical synthesis, crystals of the CuI π-complexes bis(1-allyl-2-aminopyridinium) di-μ-chloro-bis[chlorocopper(I)], (C8H11N2)2[Cu2Cl4] or [H2NC5H4NC3H5][CuCl2], and bis(1-allyl-2-aminopyridinium) di-μ-(chloro/bromo)-bis[(chloro/bromo)copper(I)], (C8H11N2)2[Cu2Br2.2Cl1.8] or [H2NC5H4NC3H5][CuBr1.10Cl0.90], have been obtained and structurally investigated. In each of the isostructural (isomorphous) compounds, the distorted tetrahedral Cu environment involves three halide atoms and the C=C bond of the ligand. Both compounds reside on inversion centres, and the dimeric [Cu2 X 4·2H2NC5H4NC3H5] units are bonded into a three-dimensional structure by N—H...X hyd…

Synthesis and characterization of NdNiO3 prepared by low temperature methods

1992

Abstract NdNiO3 has been prepared with an orthorhombic perovskite structure by a low temperature and low oxygen pressure method starting from a nickel(III) oxide precursor, β-NiO(OH). The compound LaNiO3 has also been obtained by this method. This chemical-precursor-based synthesis overcomes problems related to the use of high oxygen pressures in the synthesis.

Phase Separation and Nematic Order in Lyotropic Solutions: Two Types of Polymers with Different Stiffnesses in a Common Solvent

2021

The interplay of the isotropic-nematic transition and phase separation in lyotropic solutions of two types of semiflexible macromolecules with pronounced difference in chain stiffness is studied by Density Functional Theory and Molecular Dynamics simulations. While the width of the isotropic-nematic two-phase coexistence region is narrow for solutions with a single type of semiflexible chain, the two-phase coexistence region widens for solutions containing two types of chains with rather disparate stiffness. In the nematic phase, both types of chains contribute to the nematic order, with intermediate values of the order parameter compared to the corresponding single component solutions. As …

2020

Tristriazolotriazines (TTTs) with a threefold alkoxyphenyl substitution were prepared and studied by DSC, polarized optical microscopy (POM) and X-ray scattering. Six pentyloxy chains are sufficient to induce liquid-crystalline behavior in these star-shaped compounds. Thermotropic properties of TTTs with varying substitution patterns and a periphery of linear chains of different lengths, branching in the chain and swallow-tails, are compared. Generally, these disks display broad and stable thermotropic mesophases, with the tangential TTT being superior to the radial isomer. The structure–property relationships of the number of alkyl chains, their position, length and structure were studied.