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81.
Céline?Besnard Christian?Kloc Theo?Siegrist Krystian?PlutaEmail author 《Journal of chemical crystallography》2005,35(9):731-736
The title compound 1 (C24H15N3S) crystallizes in an orthorhombic unit cell, with a = 8.2355(3), b = 19.1499(8), and c = 11.3520(5) Å, Z = 2, and space group Pnma. The pentacyclic ring system is folded mainly along the S–N(2) axis and slightly along the C(3)–C(4) and C(3′)–C(4′) axes. The butterfly folding angle between the two quinoline planes is 48.96(3)∘ and the angle between the planes of the two halves of the thiazine ring is 43.46(7)∘. The central thiazine ring is in a boat conformation. The phenyl substituent is unexpectedly in an axial location with respect to the thiazine ring with the C–N⋅ < eqid1 > ⋅S angle of 114.0(1)∘ and it is perpendicular to the bisecting plane of the pentacyclic ring system. 相似文献
82.
Pieter F. W. Stouten Theo G. Prins Albert J. M. Duisenberg Jan A. Kanters Narinder S. Poonia 《Journal of chemical crystallography》1991,21(5):553-557
Na+ [C6H2(NO2)3O]– H2O,M
r=269.11, monoclinic,C2/m (No. 12),a=13.065(1),b=20.065(2),c=3.6957(4) Å,=90.75(1)°,V=968.7(1) Å3,Z=4,D
m=1.848 g cm–3 (by flotation),D
x=1.845 g cm–3, (CuK)=1.54184 Å,(CuK)=17.5 cm–1,F(000)=540,T=295 K,R=0.055,wR=0.060 for 879 observed reflections withI2.5(I). p]In the structure the picrate anion has exact twofold symmetry, the water molecule has exact mirror symmetry and the two sodium cations occupy special positions on inversion centers at (0, 1/2, 0) and (1/2, 1/2, 1/2). The phenyl ring together with the four substituent N and O atoms is strictly planar, but the phenyl ring is severely distorted from hexagonal symmetry, as is commonly observed in structures containing the picrate fragment. Both sodium ions are eight-coordinated with Na(1) and Na(2) in a cubic and distorted cubic arrangement, respectively. Na(1) coordinates to four charged phenoxide O atoms and four O atoms of nitro groups, and Na(2) to four O atoms of nitro groups and four water molecules. The water molecule donates two hydrogen bonds to symmetry-related O(2) atoms ofortho nitro groups. Two symmetry-related O(3) atoms ofortho nitro groups serve as acceptors in a very unusual asymmetric bifurcated C-HO hydrogen bond. 相似文献
83.
84.
Let F be a field. We construct many subgroups of \({{\rm GL}_2(F(t))}\) that act regularly on \({F(t)^2{\setminus}\{0\}}\), and we show that the corresponding nearfields are not Dickson nearfields if chara \({F \ne 2}\). 相似文献
85.
A theory is presented for lambdaC, the coefficient of the first-order correction in the density of the collective diffusion coefficient, for protein spheres interacting by electrostatic and adhesive forces. An extensive numerical analysis of the Stokesian hydrodynamics of two moving spheres is given so as to gauge the precise impact of lubrication forces. An effective stickiness is introduced and a simple formula for lambdaC in terms of this variable is put forward. A precise though more elaborate approximation for lambdaC is also developed. These and numerically exact expressions for lambdaC are compared with experimental data on lysozyme at pH 4.5 and a range of ionic strengths between 0.05M and 2M. 相似文献
86.
Gilles?Lenfant Marie-Claude?Heuzey Theo?G.?M.?van de?Ven Pierre?J.?CarreauEmail author 《Rheologica Acta》2017,56(1):51-62
This paper addresses the effect of monovalent (Na+) and divalent (Ca2+) ions on the shear viscosity and viscoelastic properties of two different aqueous suspensions of nanoparticles, cellulose nanocrystals (CNCs), and electrosterically stabilized nanocrystals of cellulose (ECNCs). ECNC is similar as CNC, but with carboxylated cellulose chains protruding from both endcaps. The different suspensions were studied in the semi-dilute regime, which corresponded to concentrations ranging from 0.5 to 8 wt% for CNCs and from 0.6 to 9 wt% for ECNCs. As the charges on CNCs are presumably distributed all along the crystal domains and the CNC have a twist in their backbone structure, their suspensions shifted to a cholesteric state as the volume fraction increased while ECNC suspensions did not. This is because the charges on ECNCs are mainly distributed at the endcaps of the particles and the protruding chains expel each other. On the one hand, it was demonstrated that at moderate ionic strength (I = 20 mM), CNC suspensions formed gels even at really low concentrations due to agglomeration. Calcium chloride (CaCl2) had a greater effect than sodium chloride (NaCl) on both shear and viscoelastic properties due to stronger network formation. On the other hand, ECNCs could withstand much higher ionic strengths than CNCs. NaCl had no effect other than making the ECNC particles precipitate above a concentration of 200 mM, while CaCl2 made ECNC suspensions turn into gels due to a bridging effect with their carboxylic acid groups at a concentration of [Ca2+] ≈ [COOH]/2. 相似文献
87.
88.
Cline Besnard Christian Kloc Theo Siegrist Christer Svensson Krystian Pluta 《Acta Crystallographica. Section C, Structural Chemistry》2005,61(6):o377-o379
The molecules of the title compound, C26H15N3S, have a pentacyclic ring system which is almost planar, with the central ring in a flattened boat conformation. The folding angle between the two quinoline rings is 6.75 (7)°. The 14‐phenyl substituent is in a quasi‐axial conformation, while the 14‐cyano substituent is in a quasi‐equatorial conformation with respect to the thiopyran ring. The S⋯C—Cphenyl and S⋯C—CCN angles are 116.8 (2) and 129.3 (2)°, respectively. The plane of the phenyl group is nearly coplanar with the plane bisecting the dihedral angle of the pentacyclic ring system. 相似文献
89.
Andrea Schuy Theo Woike Dominik Schaniel 《Journal of Sol-Gel Science and Technology》2009,50(3):403-408
Photoswitchable hybrid materials are successfully prepared by embedding guanidinium nitroprussides (GuNP, (CN3H6)2[Fe(CN)5NO]) into mesopores of transparent xerogel monoliths. The such prepared hybrid materials exhibit a higher photostability than
the corresponding GuNP solutions, whereby the chemical stability of the [Fe(CN)5NO]2−-anion in titania gel is nearly infinite. By irradiation with light in the blue-green spectral range one nitrosyl isomer is
formed by a 180° rotation of the NO ligand changing the Fe–NO into a Fe–ON coordination (SI), which is detected by the shift
of the ν(NO) stretching vibration from 1945 cm−1 (Fe–NO) to 1820 cm−1 (Fe–ON). Consequently there is enough space around the NO-ligand for such movement in xerogel mesopores. The embedding in
silica xerogels increases the achievable population of the isomeric nitrosyl configuration to about 15% with respect to a
single crystalline powder where only 9% are reached. 相似文献
90.
Reduced binaural performance of hearing-impaired listeners may not only be caused by raised hearing thresholds (reduced audibility), but also by supra-threshold coding deficits in signal cues. This question was investigated in the present study using binaural intelligibility level difference (BILD) comparisons: the improvement of speech-reception threshold scores for N(0)S(π) relative to N(0)S(0) presentation conditions. Investigated was what types of supra-threshold deficits play a role in reducing BILDs in hearing-impaired subjects. BILDs were investigated for 25 mild to moderate sensorineural hearing-impaired listeners, under conditions where optimal audibility was assured. All stimuli were bandpass filtered (250-4000 Hz). A distortion-sensitivity approach was used to investigate the sensitivity of subjects BILDs to external stimulus perturbations in the phase, frequency, time, and intensity domains. The underlying assumption of this approach was that an auditory coding deficit occurring in a signal cue in a particular domain will result in a low sensitivity to external perturbations applied in that domain. Compared to reference data for listeners with normal BILDs, distortion-sensitivity data for a subgroup of eight listeners with reduced BILDs suggests that these reductions in BILD were caused by coding deficits in the phase and time domains. 相似文献