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Search Results: 1 - 10 of 1027 matches for " Wilhelm Seichter "
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Tobias Gruber,Wilhelm Seichter,Edwin Weber
Acta Crystallographica Section E , 2010, DOI: 10.1107/s1600536810002424
Abstract: The asymmetric unit of the title compound, C17H12O, contains two molecules, in which the fused aromatic ring systems are almost planar [maximum deviations = 0.0529 (9) and 0.0256 (9) ]. In the crystal, aromatic π–π stacking interactions (perpendicular distance of centroids of about 3.4 ) and strong O—H...O hydrogen bonds result in a helical arrangement of pyrenyl dimers.
Structural conditions required for the bridge lithiation and substitution of a basic calix[4]arene
Conrad Fischer,Wilhelm Seichter,Edwin Weber
Beilstein Journal of Organic Chemistry , 2011, DOI: 10.3762/bjoc.7.188
Abstract: Lithiation and subsequent reaction with CO2 was applied to calix[4]arenes with different, equal or mixed, ether functions at the lower-rim site as well as tert-butylated or non-tert-butylated upper-rim positions. Whereas this reaction fails for symmetric calix[4]arene ethers with alkoxy residues greater than methoxy, the carboxylation of mixed methoxy-propoxy calixarene ethers is possible. In connection with this, several new monobridge-substituted calix[4]arenes were characterized with respect to their conformational behaviour in solution and the X-ray crystal structure of one key intermediate is taken into consideration.
Nadine Seidel,Wilhelm Seichter,Edwin Weber
Acta Crystallographica Section E , 2012, DOI: 10.1107/s1600536812004229
Abstract: In the title compound, C14H8Br2N2O2, the molecular structure features intramolecular N—H...O [2.639 (2) and 130°] and N—H...Br [3.053 (2) and 114°] hydrogen bonding. Due to inversion symmetry, the asymmetric part of the unit cell consits of one half-molecule. In the crystal, inversion dimers linked by pairs of N—H...O [2.955 (2) and 135°] hydrogen bonds occur. The structure also features C=O...π [3.228 (2) ] and Br...Br [3.569 (1) ] contacts.
Conrad Fischer,Guisheng Lin,Wilhelm Seichter,Edwin Weber
Acta Crystallographica Section E , 2009, DOI: 10.1107/s1600536809023137
Abstract: In the title compound, C55H69BrO4, the calixarene molecule displays a `partial cone' conformation bearing the lateral substituent in a sterically favorable equatorial arrangement between two syn-orientated arene units. The crystal packing is stabilized by weak C—H...π contacts, involving one tert-butyl group, and π–stacking interactions of the lateral bromobenzene units [centroid–centroid distance = 3.706 (1) ].
Nadine Seidel,Sebastian Förster,Wilhelm Seichter,Edwin Weber
Acta Crystallographica Section E , 2012, DOI: 10.1107/s1600536812017710
Abstract: The asymmetric unit of the title compound, C24H26S2, consits of one half-molecule, which is located on a center of inversion. The two benzene rings are exactly coplanar while the tert-butyl group is oriented nearly perpendicular to the ring plane [C—S—C—C = 81.14 (11)°].
2-Aminoterephthalic acid N,N-dimethylformamide disolvate
Stefan Loos,Wilhelm Seichter,Edwin Weber,Florian Mertens
Acta Crystallographica Section E , 2012, DOI: 10.1107/s1600536812031431
Abstract: The asymmetric unit of the title structure, C8H7NO4·2C3H7NO, contains one 2-aminoterephthalic acid and two N,N-dimethylformamide molecules. Strong O—H...O hydrogen bonds between the acidic carboxy H atoms of 2-aminoterephthalic acid and the O atoms of both solvent molecules form linear 1:2 complex units. One H atom of the amine group is involved in intramolecular N—H...O hydrogen bonding, whereas the second one takes part in an intermolecular N—H...O connection. Furthermore, the crystal is stabilized by weak C—H...O hydrogen bonds.
Sebastian Förster,Frank Eissmann,Wilhelm Seichter,Edwin Weber
Acta Crystallographica Section E , 2011, DOI: 10.1107/s1600536811017569
Abstract: There are two molecules in the asymmetric unit of the title compound, C14H6F6O2, in which the azulene systems possess an almost planar geometry with maximum deviations of 0.0438 (15) and 0.0396 (14) . Besides intra- and intermolecular C—H...O and C—H...F interactions, the structure displays three F...F contacts [2.793 (2), 2.8820 (17) and 2.9181 (16) ]. Furthermore, a characteristic azulene π-stacking is observed with an alternating sequence of electron-rich five-membered rings and electron-deficient seven-membered rings [centroid–centroid distances = 3.5413 (12), 3.6847 (12), 3.5790 (12) and 3.7718 (12) ].
Conrad Fischer,Tobias Gruber,Wilhelm Seichter,Edwin Weber
Acta Crystallographica Section E , 2008, DOI: 10.1107/s1600536808016164
Abstract: The molecule of the title compound, C24H36N2O2S, displays a U-shaped conformation. The prominent intermolecular interactions are N—H...O hydrogen bonds, resulting in the formation of dimers. Additional C—H...π contacts involving one of the methylene groups of the macrocycle and the naphthalene rings of a neighbouring molecule stabilize the packing structure. In the crystal structure, the cyclododecyl ring is disordered over two positions; the site occupancy factors are ca 0.86 and 0.14.
Conrad Fischer,Stefanie F. Helas,Wilhelm Seichter,Edwin Weber
Acta Crystallographica Section E , 2008, DOI: 10.1107/s1600536808022186
Abstract: In the title compound (systematic name: 17-formyl-2,5,8,11,14-pentaoxabicyclo[13.4.0]nonadeca-15,17,19-triene), C15H20O6, the 15-crown-5 ring adopts a twisted conformation. The formyl group is coplanar with the benzene ring. The crystal packing is stabilized by C—H...O interactions involving the C=O group and ether O atoms as acceptors and methylene CH groups as donors.
5,11,17,23-Tetra-tert-butyl-25,26,27,28-tetramethoxycalix[4]arene dichloromethane hemisolvate
Conrad Fischer,Tobias Gruber,Wilhelm Seichter,Diana Schindler
Acta Crystallographica Section E , 2008, DOI: 10.1107/s1600536808002304
Abstract: In the title compound, C48H64O4·0.5CH2Cl2, both crystallographically independent calixarene molecules display a partial cone conformation. Their crystal packing is stabilized by C—H...π contacts involving the methoxy groups. The solvent molecule is located interstitially between two calixarene units with C—H...Cl contacts to methoxy and tert-butyl groups. One tert-butyl residue of each calixarene molecule is disordered over two positions (occupancies 0.60/0.40 and 0.63/0.37), resulting in bond distances that deviate from ideal values. The tetramer calixarene molecules present models with approximate non-crystallographic Cs symmetry.
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