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Damon A. Parrish A. Alan Pinkerton 《Acta Crystallographica. Section C, Structural Chemistry》2003,59(2):o80-o82
The title solvate of the steroid 17β‐estradiol (E2) with methanol and water, C18H24O2·0.67CH4O·0.33H2O, is the first E2 derivative to contain three crystallographically independent molecules in the asymmetric unit. The three steroid molecules, along with two methanol molecules and a water molecule, create a three‐dimensional hydrogen‐bonded system. Three‐sided columns are formed, with the estradiol molecules aligned lengthwise parallel to (101), and joined by solvent molecules at both hydrophilic ends. The three estradiol molecules differ slightly in their ring‐bowing angles, i.e. the angle between the mean plane of the A ring and that of the BCD ring; this angle ranges from 7.1 to 12.2°. 相似文献
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Thomas Steiner 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(8):1033-1034
In the crystalline 1:1 molecular complex of triphenylmethanol (TPMeOH) and triphenylphosphine oxide (TPPO), C19H16O·C18H15OP, molecular dimers are formed which are linked by O—H?O=P hydrogen bonds. The dimers are aligned by sixfold phenyl embraces to form columns. The structure is disordered with half a dimer per asymmetric crystal unit, i.e. with only one molecular site which is half‐occupied by both TPMeOH and TPPO. 相似文献
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Tsonko Kolev Zornitza Glavcheva Rosica Petrova Olyana Angelova 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(1):110-112
In the title compound, NH4+·C4HO4?·H2O, the hydrogen squarate anions and water molecules are arranged to form planes almost parallel to bc. The ammonium cations are located between these planes and cross‐link them in the a direction by means of an extensive network of hydrogen bonds. There are two symmetry‐independent sets of cations and anions. One of the hydrogen squarate anions and one of the ammonium cations are situated on a twofold axis and the H atoms of these moieties are disordered over the symmetry‐related sites. 相似文献
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Christian Braud Guy Muller Jean-Claude Fenyo Eric Selegny 《Journal of polymer science. Part A, Polymer chemistry》1974,12(12):2767-2778
The effect of ionization on the potentiometric and viscometric behavior of both poly(methacrylic acid) (PMA) and poly(acrylic acid) (PAA) was investigated in methanol–water mixtures. The potentiometric and viscosity data revealed that the conformational change which takes place for PMA in water gradually disappears with increasing content of methanol in methanol–water mixtures. For mixtures containing 40 and 50% methanol, the behavior of PMA solutions becomes similar to that of PAA, i.e., the discontinuity versus the degree of ionization is no longer detectable and the molecule unfolds regularly upon ionization. The addition of methanol leads to the breakdown of the compact structure of PMA which is stabilized, at low degree of ionization in water, by nonelectrostatic interactions between the methyl groups of PMA. 相似文献
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Selena L. Staun Allen G. Oliver 《Acta Crystallographica. Section C, Structural Chemistry》2012,68(2):o84-o87
4‐Hydroxypyridine and terephthalic acid cocrystallize as a hydrate, 4‐pyridone–terephthalic acid–water (2/1/2), 2C5H5NO·C8H6O4·2H2O, from a methanol–water solution. The molecules form a two‐dimensional hydrogen‐bonded network resulting in sheets of hydrogen‐bonded molecules that lie parallel to the (10) plane. In contrast, 3‐hydroxypyridine and terephthalic acid form the salt bis(3‐hydroxypyridinium) terephthalate, 2C5H6NO+·C8H4O42−, giving rise to two‐dimensional hydrogen‐bonded sheets extending through the lattice parallel to the (10) plane. 相似文献
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Katarzyna A. Solanko Artem O. Surov German L. Perlovich Annette Bauer‐Brandl Andrew D. Bond 《Acta Crystallographica. Section C, Structural Chemistry》2012,68(11):o456-o458
The title compound, C18H19Cl2NO4·C6H12N2·H2O, is a cocrystal hydrate containing the active pharmaceutical ingredient felodipine and diazabicyclo[2.2.2]octane (DABCO). The DABCO and water molecules are linked through O—H...N hydrogen bonds into chains around 21 screw axes, while the felodipine molecules form N—H...O hydrogen bonds to the water molecules. The felodipine molecules adopt centrosymmetric back‐to‐back arrangements that are similar to those present in all of its four reported polymorphs. The dichlorophenyl rings also form π‐stacking interactions. The inclusion of water molecules in the cocrystal, rather than formation of N—H...N hydrogen bonds between felodipine and DABCO, may be associated with steric hindrance that would arise between DABCO and the methyl groups of felodipine if they were directly involved in hydrogen bonding. 相似文献
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Christopher B. Perry Manuel A. Fernandes Helder M. Marques 《Acta Crystallographica. Section C, Structural Chemistry》2004,60(4):m165-m167
The title compound, [Co(C5H11)(C62H88N13O14P)]·0.385C3H6O·12.650H2O, contains the isoamyl (3‐methylbutyl) anion bonded to the CoIII ion through a C atom. The compound is thus a structural analog of the two biologically important vitamin B12 coenzymes adenosylcobalamin and methylcobalamin. The lower axial Co—N bond length [2.277 (2) Å] is one of the longest ever reported for a cobalamin and reflects the strong σ‐donor ability of the isoamyl group. 相似文献