Search results for " Crystal"

Human neuroglobin: crystals and preliminary X-ray diffraction analysis

2002

Neuroglobin, a recently discovered member of the haemoglobin superfamily, is primarily expressed in the brain of humans and other vertebrates, where it has been proposed to enhance O(2) supply in response to hypoxia or ischaemia, protecting the neuron from hypoxic injury. Neuroglobin is the first example of a vertebrate haemoglobin in which a hexacoordinate haem geometry has been detected. A triple mutant (replacing three Cys residues) of human neuroglobin (151 amino acids) has been expressed in Escherichia coli, purified and crystallized in two crystal forms, the best of which diffracts to 1.95 A resolution using synchrotron radiation. The crystals belong to space group P2(1), with unit-ce…

1991

The sanidic polyamide [NM-Ph(CO 2 R) 3 (CO 2 Me)-NMCO-Ph(OR) 2 CO] n (R=C 12 H 25 ) is studied. It is shown that this polymer has a biaxial structure with quasi 2-D long range translational correlations. The correlations in one direction are limited by the length of the molecule. The oriented regions are separated by regions in which the molecules are less oriented

Deuteron NMR Relaxation Studies of Combined Main-Chain/Side-Chain Polymers in the Liquid Crystalline and Glassy State

1989

Etude du polymere [O−Ph−CO 2 −Ph(R)−O−CO−Ph−O-(CH 2 ) 10 −] n (R=(CH 2 ) 6 −O−Ph−N=N−Ph−OMe) qui est caracterise par des parametres d'ordre des mesogenes de la chaine principale tres superieurs a ceux des chaines laterales. On observe une biaxialite moleculaire dans toutes les mesophases et dans la phase smectique A

Das erste verklammerte und stark deformierte Adamantan

1990

pH-Dependent ligands as carriers in transport experiments

2004

Abstract Conformationally pH-regulated ligands have been used as carriers in transport experiments. The experiments were carried out through bulky membranes and the pH at the source phase and at the receiving phase were modified to study the ability of ligands to act as pH-regulated carriers. The influence of pH on transport efficiency seems to be related to its influence on conformational equilibrium. X-ray determination of one precursor compound has been useful for determining the stereochemistry of one of the carriers. To cite this article: A.M. Costero et al., C. R. Chimie 7 (2004).

Synthesis, Crystal Structure and Magnetic Properties of [Fe(bpe)4(H2O)2](TCNQ)2 (bpe = trans-1,2-bis(4-pyridyl)ethane and TCNQ = tetracyanoquinodimet…

2005

The synthesis, structure and magnetic properties of [Fe(bpe)4(H2O)2](TCNQ)2 (1) are reported. 1 crystallizes in the triclinic P space group, a = 13.481(5), b = 14.887(3), c = 16.663(4) A, α = 101.048(18), β = 112.84(2), γ = 90.92(2)°, V = 3009.6(14) A3, Z = 2. The iron atom defines a compressed octahedron with the equatorial positions occupied by the bpe molecules which act as monodentate ligands and the two axial positions occupied by water molecules. The TCNQ− radical counterions are uncoordinated and interact by pairs defining (TCNQ)22− units strongly coupled antiferromagnetically. The iron(II) atoms are in the high spin state and its magnetic behaviour indicates the occurrence of zero-f…

Copper complexes modelling the interaction between benzolamide and Cu-substituted carbonic anhydrase. Crystal structure of Cu(bz)(NH3)4 complex

1998

New copper benzolamide (H 2 bz, 5-phenylsulfonamide-1,3,4-thiadiazole-2-sulfonamide) complexes with ammonia, diethylentriamine (dien) and dipropylentriamine (dipn) have been prepared. The complex [Cu(bz)(NH 3 ) 4 ] crystallises in the monoclinic space group P 2 1 / n with a = 7.621(3), b = 19.91(5), c = 11.291(3) A, β = 93.17(4)° and Z = 4. The Cu(II) is five-coordinated with an almost regular square pyramidal geometry. The dideprotonated sulfonamide behaves as monodentate ligand interacting with the metal ion through the N atom of the unsubstituted sulfonamide group. In the EPR spectrum, exchange coupling between Cu(II) polyhedra of different orientations in the unit cell is observed. The …

Syntheses, crystal structures and magnetic properties of five new manganese(ii) complexes: Influence of the conformation of different alkyl/aryl subs…

2014

et al.

Bile acid–amino acid ester conjugates: gelation, structural properties, and thermoreversible solid to solid phase transition

2010

Design, synthesis, and gelation properties of three novel biocompatible bile acid–L-methionine methyl ester conjugates are presented. Two of the conjugates have been shown to undergo self-assembly leading to organogelation in certain aromatic solvents. The properties of these gels have been investigated by conventional methods typical for molecular gel studies along with 13C CPMAS NMR spectroscopic studies of the native gel. In addition, properties in solid and solution states for all three compounds have been investigated, and single crystal X-ray structures of all compounds determined. Furthermore, powder X-ray diffraction studies have revealed that compound 1 undergoes a dynamic and reve…

Anomalous diffraction profiles of alkali-halide-alkali-cyanide mixed crystals.

1986

The x-ray diffraction profiles of four mixed alkali halides-alkali cyanides have been studied. At the threshold concentration where the systems change over from ferroelastic ordering to the glass state, the profiles are highly unusual. The diffracted intensity of transverse scans along the cubic axes follows $I\ensuremath{\sim}\mathrm{exp}(\ensuremath{-}\ensuremath{\alpha}|\ensuremath{\xi}|)$, where $\ensuremath{\xi}$ is the reduced wave vector, measured from the line center.