共查询到20条相似文献,搜索用时 46 毫秒
1.
Bertrand Vivet Florine Cavelier Jean Martinez Claude Didierjean Michel Marraud Andre Aubry 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(12):1452-1454
The silaproline‐containing dipeptide N‐(3,3‐dimethyl‐1‐pivaloyl‐1‐aza‐3‐sila‐5‐cyclopentylcarbonyl)‐l ‐alanine isopropylamide, C17H33N3O3Si, has two independent molecules in the asymmetric unit and each adopts a β‐II folded conformation, where the amide on the terminal C interacts intramolecularly with the pivaloyl O atom. The five‐membered silaproline ring is Cβ‐puckered, an infrequent conformation for the homologous proline ring. 相似文献
2.
Carl Henrik Grbitz 《Acta Crystallographica. Section C, Structural Chemistry》2002,58(8):o533-o536
The crystal structure of N‐(l ‐2‐aminobutyryl)‐l ‐alanine, C7H14N2O3, is closely related to the structure of l ‐alanyl‐l ‐alanine, both being tetragonal, while the retro‐analogue 2‐(l ‐alanylamino)‐l ‐butyric acid 0.33‐hydrate, C7H14N2O3·0.33H2O, forms a new type of molecular columnar structure with three peptide molecules in the asymmetric unit. 相似文献
3.
Tsonko Kolev Michael Spiteller William S. Sheldrick Heike Mayer‐Figge 《Acta Crystallographica. Section C, Structural Chemistry》2006,62(5):o299-o300
Cations and anions of the title compound {systematic name: 1‐[4‐(aminocarbonyl)butyl]guanidinium bis(hydrogensquarate)}, C6H17N5O2+·2C4HO4−, are connected into a three‐dimensional network by intermolecular N—H⋯O hydrogen bonds between the l ‐argininamidium ammonium, amide and guanidinium functions and the hydrogensquarate carbonyl O atoms. The independent hydrogensquarate monoanions are linked into dimers by pairs of O—H⋯O′ hydrogen bonds. 相似文献
4.
Setsuo Kashino Takeo Fukunaga Hironobu Izutsu Shiho Miyashita 《Acta Crystallographica. Section C, Structural Chemistry》2001,57(5):627-631
2‐Pyridone (2‐oxopyrimidine) forms hydrogen‐bonded complexes with dicarboxylic acids, the molar ratio of 2‐pyridone/dicarboxylic acid being 2:1 for the complexes with oxalic acid (ethanedioic acid), 2C5H5NO·C2H2O4, (I), and trans‐β‐hydromuconic acid (trans‐hex‐3‐enedioic acid), 2C5H5NO·C6H8O4, (II), and 1:1 for the complexes with trans‐glutaconic acid (trans‐pent‐2‐enedioic acid), C5H5NO·C5H6O4, (III), and l ‐tartaric acid (l ‐2,3‐dihydroxybutanedioic acid), C5H5NO·C4H6O6·H2O, (IV). Common features in the hydrogen‐bonding patterns were found for the centrosymmetric and non‐centrosymmetric acids, respectively. The 2‐pyridone molecule takes the lactam form in these crystals. 相似文献
5.
Akiko Asano Takeshi Yamada Atsushi Numata Mitsunobu Doi 《Acta Crystallographica. Section C, Structural Chemistry》2003,59(9):o488-o490
The title compound, 1‐cyclohexylmethyl‐1‐de(1‐methylpropyl)ascidiacyclamide N,N‐dimethylacetamide dihydrate, C39H56N8O6S2·C4H9NO·2H2O, a cyclohexylalanine‐incorporated ascidiacyclamide analogue ([Cha]ASC), shows a square form similar to natural ASC. On the other hand, CD (circular dichroism) spectra showed [Cha]ASC to have a folded structure in solution, making it the second known analogue to show a discrepancy between its crystal and solution structures. Moreover, the cytotoxicity of [Cha]ASC (ED50 = 5.6 µg ml−1) was approximately two times stronger than that of natural ASC or a related phenylalanine‐incorporated analogue, viz. cyclo(‐Phe–Oxz–d ‐Val–Thz–Ile–Oxz–d ‐Val–Thz‐) ([Phe]ASC), and was confirmed to be associated with the square form. However, [Phe]ASC was previously shown to be folded in the crystal structure, which suggests that the difference between the aromatic and aliphatic rings affects the molecular folding of the ASC molecule. 相似文献
6.
R. Chitra Vijay Thiruvenkatam R. R. Choudhury M. V. Hosur T. N. Guru Row 《Acta Crystallographica. Section C, Structural Chemistry》2007,63(1):o11-o13
The title bis(glycyl‐l ‐aspartic acid) oxalate complex {systematic name: bis[2‐(2‐ammonioacetamido)butanedioic acid] oxalate 0.4‐hydrate}, 2C6H11N2O5+·C2O42−·4H2O, crystallizes in a triclinic space group with the planar peptide unit in a trans conformation. The asymmetric unit consists of two glycyl‐l ‐aspartic acid molecules with positively charged amino groups and neutral carboxyl groups, and an oxalate dianion. The twist around the C—Cα bond indicates that both the peptide molecules adopt extended conformations, while the twist around the N—Cα bond shows that one has a folded and the other a semi‐extended state. The present complex can be described as an inclusion compound with the dipeptide molecule as the host and the oxalate anion as the guest. The usual head‐to‐tail sequence of aggregation is not observed in this complex, as is also the case with the glycyl‐l ‐aspartic acid dihydrate molecule. The study of aggregation and interaction patterns in binary systems is the first step towards understanding more complex phenomena. This further leads to results that are of general interest in bimolecular aggregation. 相似文献
7.
Jyoti Makker Sharmistha Dey Pravindra Kumar Tej P. Singh 《Acta Crystallographica. Section C, Structural Chemistry》2002,58(4):o212-o214
The title peptide N‐benzyloxycarbonyl–ΔLeu–l ‐Ala–l ‐Leu–OCH3 [methyl N‐(benzyloxycarbonyl)‐α,β‐dehydroleucyl‐l ‐alanyl‐l ‐leucinate], C24H35N3O6, was synthesized in the solution phase. The peptide adopts a type II′β‐turn conformation which is stabilized by an intramolecular 4 1 N—H?O hydrogen bond. The crystal packing is stabilized by two intermolecular N—H?O hydrogen bonds. 相似文献
8.
Carl Henrik Grbitz 《Acta Crystallographica. Section C, Structural Chemistry》2003,59(12):o730-o732
The side chains of l ‐alanyl‐l ‐methionine hemihydrate, C8H16N2O3S·0.5H2O, form hydrophobic columns within a three‐dimensional hydrogen‐bond network that includes extended polymers of cocrystallized water molecules and Cα—H⋯S interactions. 相似文献
9.
Elbieta Jankowska Mirosaw Gilski Mariusz Jasklski Zbigniew Grzonka Leszek ankiewicz 《Acta Crystallographica. Section C, Structural Chemistry》2002,58(6):o353-o354
The crystal structure of the title compound, alternatively called 3‐[4‐(benzyloxy)phenyl]‐2‐(N‐tert‐butoxycarbonyl‐N‐methylamino)propionic acid, C22H27NO5, has been studied in order to examine the role of N‐methylation as a determinant of peptide conformation. The conformation of the tert‐butoxycarbonyl group is trans–trans. The side chain has a folded conformation and the two phenyl rings are effectively perpendicular to one another. The carboxylate hydroxyl group and the urethane carbonyl group form a strong intermolecular O—H?O hydrogen bond. 相似文献
10.
Henrik Birkedal Dieter Schwarzenbach Philip Pattison 《Acta Crystallographica. Section C, Structural Chemistry》2001,57(8):975-977
The crystal structure of the neuroactive artificial dipeptide N‐benzyloxycarbonylprolyl‐d ‐leucine, C19H26N2O5, was solved using synchrotron radiation data collected on a very small crystal (20 × 20 × 380 μm). The molecules form hydrogen‐bonded 21 helices. The acid carbonyl group does not participate in strong hydrogen bonds. This is interpreted as a consequence of close‐packing requirements. 相似文献
11.
Urs D. Wermuth Graham Smith Jonathan M. White 《Acta Crystallographica. Section C, Structural Chemistry》2006,62(6):o353-o357
The structures of two brucinium (2,3‐dimethoxy‐10‐oxostrychnidinium) salts of the α‐hydroxy acids l ‐malic acid and l ‐tartaric acid, namely brucinium hydrogen (S)‐malate pentahydrate, C23H27N2O4+·C4H5O5−·5H2O, (I), and anhydrous brucinium hydrogen (2R,3R)‐tartrate, C23H27N2O4+·C4H5O6−,(II), have been determined at 130 K. Compound (I) has two brucinium cations, two hydrogen malate anions and ten water molecules of solvation in the asymmetric unit, and forms an extensively hydrogen‐bonded three‐dimensional framework structure. In compound (II), the brucinium cations form the common undulating brucine sheet substructures, which accommodate parallel chains of head‐to‐tail hydrogen‐bonded tartrate anion species in the interstitial cavities. 相似文献
12.
Alvaro B. Onofrio Eliezer Jger Tiago A. S. Brando Adailton J. Bortoluzzi Faruk Nome 《Acta Crystallographica. Section C, Structural Chemistry》2006,62(5):o237-o239
The title compound (with the systematic name 2‐{[(1S)‐1‐(methoxycarbonyl)‐3‐methylbutyl]aminocarbonyl}benzoic acid), C15H19NO5, crystallizes in the monoclinic space group P21, with two independent molecules per asymmetric unit. The most notable difference between the two molecules is in the dihedral angles between the planes of the carboxyl group and the benzene ring, which are 3.5 (3) and 25.7 (1)°. This difference may account for the fact that two competing reactions are observed in aqueous solution, namely cyclization to form the imide N‐phthaloylleucine and hydrolysis of N‐(2‐carboxybenzoyl)‐l ‐leucine methyl ester to phthalic acid and leucine. 相似文献
13.
Shusheng Zhang Zhongwei Wang Ming Li Kui Jiao Ibrahim Abdul Razak S. Shanmuga Sundara Raj Hoong‐Kun Fun 《Acta Crystallographica. Section C, Structural Chemistry》2001,57(5):566-568
In both the title structures, O‐ethyl N‐(2,3,4,6‐tetra‐O‐acetyl‐β‐d ‐glucopyranosyl)thiocarbamate, C17H25NO10S, and O‐methyl N‐(2,3,4,6‐tetra‐O‐acetyl‐β‐d ‐glucopyranosyl)thiocarbamate, C16H23NO10S, the hexopyranosyl ring adopts the 4C1 conformation. All the ring substituents are in equatorial positions. The acetoxymethyl group is in a gauche–gauche conformation. The S atom is in a synperiplanar conformation, while the C—N—C—O linkage is antiperiplanar. N—H?O intermolecular hydrogen bonds link the molecules into infinite chains and these are connected by C—H?O interactions. 相似文献
14.
Catherine Corbier Claude Didierjean Laurent Thvenet Regis Vanderesse Michel Marraud 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(8):995-996
The pseudodipeptide, (S)‐N‐isopropyl {[N‐(pivaloyl)pyrrolidin‐2‐yl]methylaminooxy}acetamide, C15H29N3O3, adopts a global extended conformation with the hydroxylamine group in the g+/g? structure. The C‐terminal amide NH interacts intramolecularly with the hydroxylamine O atom. Both NH bonds of each molecule are hydrogen bonded to the C‐terminal amide carbonyl of a neighbouring molecule. 相似文献
15.
Raffaella Puliti Carlo Andrea Mattia 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(4):496-499
Ammonium N‐acetyl‐l ‐threoninate, NH4+·C6H10NO4?, and methylammonium N‐acetyl‐l ‐threoninate, CH6N+·C6H10NO4?, crystallize in the orthorhombic P212121 and monoclinic P21 space groups, respectively. The two crystals present the same packing features consisting of infinite ribbons of screw‐related N‐acetyl‐l ‐threoninate anions linked together through pairs of hydrogen bonds. The cations interconnect neighbouring ribbons of anions involving all the nitrogen‐H atoms in three‐dimensional networks of hydrogen bonds. The hydrogen‐bond patterns include asymmetric `three‐centred' systems. In both structures, the Thr side chain is in the favoured (g?g+) conformation. 相似文献
16.
Marius Bruvoll Selma Dizdarevic Nina Fimland Jasmina Hafizovic Carl Henrik Grbitz Helen Therese Kalfjs Kristian Vestli Alexander Krivokapic 《Acta Crystallographica. Section C, Structural Chemistry》2006,62(1):o22-o25
The structures of the title dipeptides, C9H18N2O4·0.33H2O, C12H16N2O4 and C8H16N2O4S·0.34H2O, complete a series of investigations focused on l ‐Xaa‐l ‐serine peptides, where Xaa is a hydrophobic residue. All three structures are divided into hydrophilic and hydrophobic layers. The hydrophilic layers are thin for l ‐phenylalanyl‐l ‐serine, rendered possible by an unusual peptide conformation, and thick for l ‐isoleucyl‐l ‐serine and l ‐methionyl‐l ‐serine, which include cocrystallized water molecules on the twofold axes. 相似文献
17.
Yuekun Zhao Madeleine Helliwell John A. Joule 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(6):714-715
Vilsmeier formylation of trans‐1‐(4‐methylphenylsulfonyl)‐2,5‐bis(pyrrol‐2‐yl)pyrrolidine leads to cleavage of the central ring then a reclosure resulting in the formation of trans‐N‐[2‐formyl‐4‐(5‐formylpyrrol‐2‐yl)‐4,5,6,7‐tetrahydroindol‐7‐yl]toluenesulfonamide, C21H21N3O4S. 相似文献
18.
Jiwen Cai Xiaopeng Hu Cai‐Hong Chen Liang‐Nian Ji 《Acta Crystallographica. Section C, Structural Chemistry》2001,57(4):394-396
The racemic title compound, trans‐[N,N‐bis(2‐aminoethyl)‐1,2‐ethanediamine‐κ4N](dl ‐isoleucinato‐N,O)cobalt(III) diperchlorate, [Co(C6H18N4)(C6H12NO2)](ClO4)2, crystallizes in the enantiomorphous space group P212121 with Z = 12 (Z′ = 3). Each of the three cations in the asymmetric unit represents a different chirality of the isoleucine ligand; two of them are R (or d ) and the third is the S (or l ) enantiomer. The mixture crystallizes in a so‐called unbalanced crystallization, in which the cations adopt a chiral array of composition RRS or SSR, depending on the crystal selected for data collection. 相似文献
19.
Frank Seela Matthias Zulauf Hans Reuter Guido Kastner 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(4):489-491
The isomorphous structures of the title molecules, 4‐amino‐1‐(2‐deoxy‐β‐d ‐erythro‐pentofuranosyl)‐3‐iodo‐1H‐pyrazolo‐[3,4‐d]pyrimidine, (I), C10H12IN5O3, and 4‐amino‐3‐bromo‐1‐(2‐deoxy‐β‐d ‐erythro‐pentofuranosyl)‐1H‐pyrazolo[3,4‐d]pyrimidine, (II), C10H12BrN5O3, have been determined. The sugar puckering of both compounds is C1′‐endo (1′E). The N‐glycosidic bond torsion angle χ1 is in the high‐anti range [?73.2 (4)° for (I) and ?74.1 (4)° for (II)] and the crystal structure is stabilized by hydrogen bonds. 相似文献
20.
Frank Seela Helmut Rosemeyer Alexander Melenewski Eva‐Maria Heithoff Henning Eickmeier Hans Reuter 《Acta Crystallographica. Section C, Structural Chemistry》2002,58(3):o142-o144
In the monohydrate of 2‐amino‐8‐(2‐deoxy‐α‐d ‐erythro‐pentofuranosyl)‐8H‐imidazo[1,2‐a][1,3,5]triazin‐4‐one, C10H13N5O4·H2O, denoted (I) or αZd, the conformation of the N‐glycosylic bond is in the high‐anti range [χ = 87.5 (3)°]. The 2′‐deoxyribofuranose moiety adopts a C2′‐endo,C3′‐exo(2′T3′) sugar puckering (S‐type sugar) and the conformation at the C4′—C5′ bond is ?sc (trans). 相似文献