共查询到20条相似文献,搜索用时 515 毫秒
1.
Shunpei Nobusue Yuichi Mukai Yo Fukumoto Dr. Rui Umeda Dr. Kazukuni Tahara Dr. Motohiro Sonoda Prof. Yoshito Tobe 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(40):12814-12824
A new class of propel‐ ler‐shaped compound ( 4 ), which consisted of dehydrobenzo[14]annulene ([14]DBA) blades, as well as its naphtho homologues ( 5 and 6 ), have been prepared. Although NMR studies of compound 4 did not provide useful information regarding its conformation in solution, DFT calculations with different functionals and the 6‐31G* basis set all indicated that the D3‐symmetric structure was energetically more favorable than the C2 conformer. From X‐ray crystallographic analysis, it appeared that compound 4 adopted a propeller‐shaped‐, approximately D3‐symmetric structure in the solid state, in which the [14]DBA blades were twisted substantially owing to steric repulsion between the neighboring benzene rings. On the contrary, in the case of compound 6 , although the DFT calculations with the B3LYP functional predicted that the D3‐symmetric conformation was more stable, calculations with the M05 and M05‐2X functionals indicated that the C2 conformer was more favorable because of π–π interactions between the naphthalene units of a pair of neighboring blades. Indeed, X‐ray analysis of compound 6 showed that it adopted an approximately C2‐symmetric conformation. Moreover, on the basis of variable‐temperature 1H NMR measurements, we found that compound 6 adopted a C2 conformation and the barrier for interconversion between the C2–C2 conformers was estimated to be 16.2 kcal mol?1; however, no indication of the presence of the D3 isomer was obtained. The relatively small energy barriers to interconversion, despite the large overlapping of neighboring blades, was ascribed to the flexibility of the acetylene linkages, which could be deformed substantially in the transition state of the ring‐flip. 相似文献
2.
Patrick Plitt Frank Rominger Roland Krmer 《Acta Crystallographica. Section C, Structural Chemistry》2005,61(6):o396-o397
The title compound, 8,15,28,35‐tetraazaheptacyclo[35.3.1.12,6.117,21.122,26.09,14·029,34]tetraconta‐1(41),2,4,6(42),7,9,11,13,15,17,19,21(43),22,24,26(44),27,29,31,33,35,37,39‐docosaene‐41,42,43,44‐tetrol dimethyl sulfoxide tetrasolvate, C40H28N4O4·4C2H6OS, adopts a chair‐shaped C2h symmetric conformation with crystallographically imposed inversion symmetry. Four intramolecular hydrogen bonds are observed between phenol O and imine N atoms. 相似文献
3.
Gary S. Nichol Francis N. Murigi Eugene A. Mash 《Acta Crystallographica. Section C, Structural Chemistry》2010,66(6):o302-o304
Synchrotron radiation was used to study the structure of the title compound, C20H19BrN2O3·C3H7NO, which was obtained as fine fragile needle‐shaped crystals by recrystallization from dimethylformamide (DMF), one molecule of which is incorporated per asymmetric unit into the crystal. The compound adopts a compact closed conformation with the orientation of the benzyl group such that the aryl ring is positioned over the piperazinedione ring, resulting in a Cspiro...Ctrans—C—CPh pseudo‐torsion angle of −3.3 (3)°. The five‐membered ring is present in an expected envelope conformation and the six‐membered piperazinedione ring adopts a less puckered boat‐like conformation. Reciprocal amide‐to‐amide hydrogen bonding between adjacent piperazinedione rings and C—H...O interactions involving DMF molecules propagate in the crystal as a thick ribbon in the a‐axis direction. 相似文献
4.
《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(16):4669-4673
In achiral rod‐like molecules, a nematic phase is the most disordered liquid crystal phase, which only has one‐directional order in the direction of the molecular long axis. A dumbbell‐shaped molecule (compound 3 : R−C6H10−CH=CH−C6H4−CH=CH−C6H10−R, (R=n C5H11)), and its liquid crystal phase (X phase) are reported, which exhibit high scattering without thermal fluctuation between two nematic phases under a polarized light optical microscope. The X phase was investigated by X‐ray diffraction, scanning electron microscopy, atomic force microscopy, and molecular dynamics simulation. A layered structure was ascertained for which a molecular self‐organization mechanism was postulated in which the super‐structure is based on lateral intermolecular interlocking. A second nematic phase above the X phase consisted of “rice grain”‐shaped particles. 相似文献
5.
Volker Bhmer Denys Meshcheryakov Iris Thondorf Michael Bolte 《Acta Crystallographica. Section C, Structural Chemistry》2004,60(2):o136-o139
The title compound, C13H10N2O2, is the first structure in which the urea moiety is incorporated into an eight‐membered ring. Two molecules are found in the asymmetric unit, which are almost identical in their conformation and their hydrogen‐bond pattern. The carbonyl O atom acts as a double acceptor for the NH groups of two adjacent molecules. In this way, infinite tapes are formed, which are connected viaπ–π and edge‐to‐face interactions in the second and third dimension. This hierarchical order of interactions is confirmed by molecular mechanics calculations. Force‐field and semi‐empirical calculations for a single molecule did not find the envelope conformation present in the crystal, indicating instead a Cs conformation. Only with a model consisting of a hydrogen‐bonded dimer or a larger hydrogen‐bonded section was a conformation found that was similar to the one present in the crystal. 相似文献
6.
Gregory S. Coumbarides Jason Eames Majid Motevalli Yonas Yohannes 《Acta Crystallographica. Section C, Structural Chemistry》2002,58(2):o84-o85
The title compound, bis(2‐isopropyl‐5‐methylcyclohex‐1‐yl) malonate, C23H40O4, crystallizes in the monoclinic space group P21. In the crystal, the molecule is not C2 symmetric. 相似文献
7.
Cristian Paz Yanko Moreno Jos Becerra Mario Silva Viviana Burgos Eleonora Freire Ricardo Baggio 《Acta Crystallographica. Section C, Structural Chemistry》2013,69(7):765-769
The natural title compound, C11H12O4, extracted from the Chilean native tree Aristotelia chilensis (Maqui), is a polymorph of the synthetic E form reported by Xia, Hu & Rao [Acta Cryst. (2004), E 60 , o913–o914]. Both rotational conformers are identical from a metrical point of view, and only differ in the orientation of the 3,4‐dihydroxyphenyl ring with respect to the rest of the molecule, which leads to completely different crystal structure arrangements and packing efficiencies. The reasons behind both reside in the different hydrogen‐bonding interactions. 相似文献
8.
Valery Belakhov Mark Botoshansky Timor Baasov 《Acta Crystallographica. Section C, Structural Chemistry》2002,58(8):m450-m452
The hexopyranosyl ring of the title compound, [Hg(CH3)(C9H15O7S)], adopts the 4C1 chair conformation, and the anomeric configuration of the thiomethylmercury linkage is β. The compound exists as two symmetry‐independent conformers, A and B, within the unit cell, and each shows an almost linear S—Hg—C arrangement. Most of the bond distances and angles in A and B are similar, although a marked difference exists in the side‐chain conformation. Weak secondary intramolecular (between Hg and ring O) and intermolecular (between A and B conformers) interactions are documented. 相似文献
9.
Frank Seela Simone Budow Henning Eickmeier Hans Reuter 《Acta Crystallographica. Section C, Structural Chemistry》2007,63(1):o54-o57
The title compound, 4‐amino‐1‐(2‐deoxy‐β‐d ‐erythropentofuranosyl)‐5‐(prop‐1‐ynyl)pyrimidin‐2(1H)‐one, C12H15N3O4, shows two conformations in the crystalline state which differ mainly in the glycosylic bond torsion angle and the sugar pucker. Both molecules exhibit an anti glycosylic bond conformation, with torsion angles χ = −135.0 (2) and −156.4 (2)° for molecules 1 and 2, respectively. The sugar moieties show a twisted C2′‐endo sugar pucker (S‐type), with P = 173.3 and 192.5° for molecules 1 and 2, respectively. The crystal structure is characterized by a three‐dimensional network that is stabilized by several intermolecular hydrogen bonds between the two conformers. 相似文献
10.
Corannulene Molecular Rotor with Flexible Perfluorobenzyl Blades: Synthesis,Structure and Properties 下载免费PDF全文
Long K. San Tyler T. Clikeman Cristina Dubceac Dr. Alexey A. Popov Dr. Yu‐Sheng Chen Prof. Marina A. Petrukhina Prof. Steven H. Strauss Dr. Olga V. Boltalina 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(26):9488-9492
Two members of a new class of organic‐acceptor perfluorobenzyl corannulenes were prepared by gas‐phase and highly‐selective solution‐phase reactions at elevated temperatures. The peculiar single‐crystal X‐ray structure of C5‐C20H5(CF2C6F5)5 revealed two high‐energy conformers with drastically different bowl depths and orientations of perfluorobenzyl blades; the conformers are alternating in columnar packing arrangements and every pair is sandwiched by toluene molecules. 相似文献
11.
Pawe Wagner Mieczysaw apkowski Maciej Kubicki 《Acta Crystallographica. Section C, Structural Chemistry》2006,62(4):o155-o156
Molecules of the title compound, C20H28O4S2, the first compound with a tetraoxacyclohexacosane ring to be structurally characterized, lie on crystallographic centres of inversion, but have approximate C2h molecular symmetry. The parallel thiophene rings are almost exactly planar; the overall conformation of the molecule is chair‐like. The molecules have voids that could, in principle, accommodate small guest molecules, although in the crystal structure access to these voids is blocked by neighbouring molecules. 相似文献
12.
A. F. G. Masud Reza Shuhei Higashibayashi Dr. Hidehiro Sakurai Prof. Dr. 《化学:亚洲杂志》2009,4(8):1329-1337
C3‐symmetric homochiral (?)‐syn‐trisoxonorbornabenzene 1 possessing a rigid cup‐shaped structure was synthesized through a novel regioselective cyclotrimerization of enantiopure iodonorbornenes catalyzed by palladium nanoclusters. The yield of the cyclotrimerization was dependent on the stability of the palladium clusters, which was ascertained from the appearance and TEM images of the reaction mixtures. The efficient preparation of (?)‐syn‐ 1 was established in short steps, including the newly developed cyclotrimerization reaction. The thus‐prepared homochiral (?)‐syn‐ 1 can serve as a key intermediate for the synthesis of C3‐symmetric homochiral cup‐shaped molecules with a helical arrangement of substituents. Introduction of several types of substituents was well demonstrated through palladium‐catalyzed coupling reactions with the corresponding phosphate and triflate of (?)‐syn‐ 1 . 相似文献
13.
Zhi‐Min Jin Li Li Mei‐Chao Li Mao‐Lin Hu Liang Shen 《Acta Crystallographica. Section C, Structural Chemistry》2004,60(9):o642-o643
The title compound, C14H24N2O4, consists of two symmetric moieties related through a twofold axis. The whole molecule has a cis conformation. Both the ionic enol form and the non‐ionic keto form make comparable contributions to the structure. In the crystal structure, infinite supramolecular chains are formed through N—H⋯O hydrogen bonds. 相似文献
14.
Mohamed Abboud Amal Kadimi Victor Mamane Emmanuel Aubert 《Acta Crystallographica. Section C, Structural Chemistry》2010,66(7):o381-o384
The crystal packing of the title compound, C17H9Br2ClN2O, is governed by strong π–π stacking, where molecules are tightly bound within infinite (100) planes; these planes interact mainly through non‐optimal π–π stacking where arene rings are noticeably displaced from perfect overlap, and also through halogen–halogen interactions. The aldehyde group shows conformational disorder, with a significant population difference between the two conformers; this difference is rationalized by the energetic analysis of the crystal packing using the PIXEL method, which also allows a decomposition of intermolecular interaction energy into Coulombic, polarization, dispersion and repulsion contributions. Using such an analysis, it is found that the main reason for this unequal population of the two conformers in the crystal is two hydrogen bonds that are present only for the major conformer. 相似文献
15.
G. Prchniak J. Zo M. Daszkiewicz A. Pietraszko V. Videnova‐Adrabiska 《Acta Crystallographica. Section C, Structural Chemistry》2007,63(7):o434-o436
The crystal structure of the title compound, C12H12O6P2, displays two different regions alternating along the a axis: a hydrogen‐bonded region encompassing the end‐positioned phosphonic acid groups and a hydrophobic region formed by the aromatic spacers. The asymmetric unit contains only half of the biphenyl‐4,4′‐diphosphonic acid (4,4′‐bpdp) molecule, which is symmetric with an inversion centre imposed at the mid‐point between the two aromatic rings. The periodic organization of the molecules is controlled by two strong O—H...O interactions between the phosphonic acid sites. Weak C—H...π interactions are established in the aromatic regions. 相似文献
16.
Ilona Turowska‐Tyrk Karolina Grzeniak 《Acta Crystallographica. Section C, Structural Chemistry》2004,60(2):o146-o148
Crystals of the 1‐chloroanthracene photodimer, viz. trans‐bi(1‐chloro‐9,10‐dihydro‐9,10‐anthracenediyl), C28H18Cl2, were obtained from the solid‐state [4+4]‐photodimerization of the monomer, C14H9Cl, followed by recrystallization. The symmetry of the product molecules is defined by the orientation of the reactant molecules in the crystal. The mutual orientation parameters calculated for adjacent monomers explain the reactivity of the compound. The molecules in the crystal of the monomer and the recrystallized photodimer pack differently and the photodimer has crystallographically imposed inversion symmetry. 相似文献
17.
Bernard Omondi Manuel A. Fernandes Marcus Layh Demetrius C. Levendis 《Acta Crystallographica. Section C, Structural Chemistry》2008,64(3):o137-o138
N‐Phenylformamide, C7H7NO, crystallizes with two molecules in the asymmetric unit which have different conformations of the formylamino group, one being cis and the other trans. This is the first example of an arylformamide crystal containing both conformational isomers and it may thus be considered a cocrystal of the two conformers. The two molecules in the unit cell are linked through N—H...O hydrogen bonding to two other molecules, thereby forming hydrogen‐bonded tetramers within the crystal structure. 相似文献
18.
Yingning Gao Yanli Chen Prof. Renjie Li Yongzhong Bian Dr. Xiyou Li Prof. Jianzhuang Jiang Prof. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(47):13241-13252
To investigate the effects of metal–ligand coordination on the molecular structure, internal structure, dimensions, and morphology of self‐assembled nanostructures, two nonperipherally octa(alkoxyl)‐substituted phthalocyanine compounds with good crystallinity, namely, metal‐free 1,4,8,11,15,18,22,25‐octa(butyloxy)phthalocyanine H2Pc(α‐OC4H9)8 ( 1 ) and its lead complex Pb[Pc(α‐OC4H9)8] ( 2 ), were synthesized. Single‐crystal X‐ray diffraction analysis revealed the distorted molecular structure of metal‐free phthalocyanine with a saddle conformation. In the crystal of 2 , two monomeric molecules are linked by coordination of the Pb atom of one molecule with an aza‐nitrogen atom and its two neighboring oxygen atoms from the butyloxy substituents of another molecule, thereby forming a Pb‐connected pseudo‐double‐decker supramolecular structure with a domed conformation for the phthalocyanine ligand. The self‐assembling properties of 1 and 2 in the absence and presence of sodium ions were comparatively investigated by scanning electronic microscopy (SEM), spectroscopy, and X‐ray diffraction techniques. Intermolecular π–π interactions between metal‐free phthalocyanine molecules led to the formation of nanoribbons several micrometers in length and with an average width of approximately 100 nm, whereas the phthalocyaninato lead complex self‐assembles into nanostructures also with the ribbon morphology and micrometer length but with a different average width of approximately 150 nm depending on the π–π interactions between neighboring Pb‐connected pseudo‐double‐decker building blocks. This revealed the effect of the molecular structure (conformation) associated with metal–ligand (Pb? Nisoindole, Pb? Naza, and Pb? Obutyloxy) coordination on the dimensions of the nanostructures. In the presence of Na+, additional metal–ligand (Na? Naza and Na? Obutyloxy) coordination bonds formed between sodium atoms and aza‐nitrogen atoms and the neighboring butyloxy oxygen atoms of two metal‐free phthalocyanine molecules cooperate with the intrinsic intermolecular π–π interactions, thereby resulting in an Na‐connected pseudo‐double‐decker building block with a twisted structure for the phthalocyanine ligand, which self‐assembles into twisted nanoribbons with an average width of approximately 50 nm depending on the intertetrapyrrole π–π interaction. This is evidenced by the X‐ray diffraction analysis results for the resulting aggregates. Twisted nanoribbons with an average width of approximately 100 nm were also formed from the lead coordination compound 2 in the presence of Na+ with a Pb‐connected pseudo‐double‐decker as the building block due to the formation of metal–ligand (Na? Naza and Na? Obutyloxy) coordination bonds between additionally introduced sodium ions and two phthalocyanine ligands of neighboring pseudo‐double‐decker building blocks. 相似文献
19.
Rosana S. Montani Raúl O. Garay Fabio D. Cukiernik Maria T. Garland Ricardo Baggio 《Acta Crystallographica. Section C, Structural Chemistry》2009,65(3):o81-o84
The crystal structure of the dimeric title compound, C19H22O5, is dominated by a head‐to‐head hydrogen‐bonding interaction between centrosymmetrically related carboxyl groups in each monomer. The result is a dimeric axis of unusual length (ca 34 Å), but still shorter than what could be expected for a fully extended chain, owing to two turning points in the oligoethoxy ends. This allows for an explanation of the structure of the smectic mesophase exhibited by this compound and at the same time fully validates former geometric estimations based on PM3 calculations. 相似文献
20.
Andrian P. Milanov Raghunandan Bhakta Manuela Winter Klaus Merz Anjana Devi 《Acta Crystallographica. Section C, Structural Chemistry》2005,61(7):m370-m372
The title compound, [Hf(C11H23N2)2Cl2], is a monomeric hafnium(IV) complex containing two bidentate amidinate ligands and two cis Cl atoms. The crystals are triclinic (space group ) and there is one independent six‐coordinate monomer with a highly distorted octahedral geometry in the asymmetric unit. The reported structure is the first hafnium–amidinate complex to be characterized successfully by single‐crystal X‐ray diffraction. 相似文献