Log in

Relevant bibliographies by topics / Conformation cis / Journal articles

To see the other types of publications on this topic, follow the link: Conformation cis.

Journal articles on the topic 'Conformation cis'

Author: Grafiati

Published: 4 June 2021

Last updated: 3 February 2022

Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles

Select a source type:

Consult the top 50 journal articles for your research on the topic 'Conformation cis.'

Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.

You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.

Browse journal articles on a wide variety of disciplines and organise your bibliography correctly.

1

Refino, Andam Deatama, Mohammad Kemal Agusta, Hermawan Kresno Dipojono, and Nugraha. "First Principle Study of Hydrazine and OH^- Co-Adsorption on Ni(111) in High Coverage System." Advanced Materials Research 893 (February 2014): 35–38. http://dx.doi.org/10.4028/www.scientific.net/amr.893.35.

Full text

Abstract:

Theoretical investigation of co-adsorption process between hydrazine (N2H4) and OH- on Ni(111) is performed using density functional theory. OH- adsorption mechanisms at various adsorption sites as well as its interaction with hydrazine in various conformations (anti, cis, and gauche) are studied. The stability of OH- adsorption on nickel surface is significantly influenced by the presence of hydrazine molecule. Among the three conformations of hydrazine, OH- adsorption on nickel surface doesn't occur in cis conformation. Otherwise, co-adsorption occurs in system with gauche and anti conformat

APA, Harvard, Vancouver, ISO, and other styles

2

van Roey, P., W. A. Pangborn, R. F. Schinazi, G. Painter, and D. C. Liotta. "Absolute Configuration of the Antiviral Agent (−)-cis-5-Fluoro-1-[2-Hydroxymethyl)-1,3-Oxathiolan-5-yl]Cytosine." Antiviral Chemistry and Chemotherapy 4, no. 6 (1993): 369–75. http://dx.doi.org/10.1177/095632029300400609.

Full text

Abstract:

The structure and absolute configuration of (−)- cis-5-fluoro-1-[2-(hydroxymethyl)-1,3-oxathiolan-5-yl]cytosine (FTC), has been determined by X-ray crystallographic analysis. The results confirm that the L-isomer of the nucleoside analogue is the most active enantiomer and that the correct absolute configuration of (−)-FTC is 5-fluoro-(2′R,5′S)-(−)-1-[2-hydroxymethyl)oxathiolan-5-yl]-fluorocytosine. The two molecules in the asymmetric unit show conformations that combine conformational features of two other classes of potent antiviral nucleosides. Both oxathiolane rings have the 3′-sulphur ato

APA, Harvard, Vancouver, ISO, and other styles

3

Aji, Kumowarih Trisno, Prasetiyo Hadi Purwoko, Andam Deatama Refino, Mohammad Kemal Agusta, and Hermawan Kresno Dipojono. "Computational Density Functional Theory Study of Hydrazine Adsorption on Ni(110) Surface." Advanced Materials Research 1112 (July 2015): 217–20. http://dx.doi.org/10.4028/www.scientific.net/amr.1112.217.

Full text

Abstract:

Hydrazine adsorption on Ni(110) surface is studied using density functional theory. Adsorption of hydrazine in its critical conformations (anti, cis, and gauche) on both 0.25 ML and 0.11 ML coverages are investigated. The results reveal that on both coverage, gauche conformations are adsorbed as the most stable conformation. The stable conformation tends to shift to cis as the coverage is reduced. Density of states analysis suggests that dz2-band of Ni and pz orbital of hydrazine are responsible for bonding formation between two constituents.

APA, Harvard, Vancouver, ISO, and other styles

4

Buchanan, G. W., R. A. Kirby, and J. P. Charland. "An example of conformational disorder in solids: X-ray crystallographic and 13C CPMAS NMR studies of dibenzo and dicyclohexano-13-crown-4 ethers and some lithium complexes." Canadian Journal of Chemistry 68, no. 1 (1990): 49–58. http://dx.doi.org/10.1139/v90-011.

Full text

Abstract:

For the cis–anti–cis isomer of dicyclohexano-13-crown-4 ether, disorder has been detected in the crystal structure, with two conformations being present in the ratio of ca. 3:2. Crystal structures for two Li+ complexes of the cis–syn–cis isomer have also been determined. Representative 13C solid phase NMR spectra are presented and discussed for these systems and the related dibenzo substituted compounds. Keywords: crown ethers, solids, NMR, conformation.

APA, Harvard, Vancouver, ISO, and other styles

5

Bartalucci, Giuditta, Stuart Fisher, John R. Helliwell, et al. "X-ray crystal structures of diacetates of 6-s-cis and 6-s-trans astaxanthin and of 7,8-didehydroastaxanthin and 7,8,7′,8′-tetradehydroastaxanthin: comparison with free and protein-bound astaxanthins." Acta Crystallographica Section B Structural Science 65, no. 2 (2009): 238–47. http://dx.doi.org/10.1107/s0108768109004649.

Full text

Abstract:

The crystal structures of the 6-s-cis [s-cis-(1)] and 6-s-trans [s-trans-(1)] conformers of the diacetates of astaxanthin (AXT) and those of (3S,3′S)-7,8-didehydroastaxanthin [(3S,3′S)-3,3′-dihydroxy-7,8-didehydro-β,β-carotene-4,4′-dione (2)] and (3S,3′S)-7,8,7′,8′-tetradehydroastaxanthin [(3S,3′S)-3,3′-dihydroxy-7,8,7′,8′-tetradehydro-β,β-carotene-4, 4′-dione (3)] are reported. The conformations of these four molecules vary in particular with the angle of twist of the end rings out of the plane of the polyene chain; for s-cis-(1), the end rings are twisted out of the plane of the polyene chai

APA, Harvard, Vancouver, ISO, and other styles

6

Alvarez, Maria, Edgardo Saavedra, Mónica Olivella, Fernando Suvire, Miguel Zamora, and Ricardo Enriz. "Theoretical study of the conformational energy hypersurface of cyclotrisarcosyl." Open Chemistry 10, no. 1 (2012): 248–55. http://dx.doi.org/10.2478/s11532-011-0136-1.

Full text

Abstract:

AbstractThe multidimensional Conformational Potential Energy Hypersurface (PEHS) of cyclotrisarcosyl was comprehensively investigated at the DFT (B3LYP/6-31G(d), B3LYP/6-31G(d,p) and B3LYP/6-311++G(d,p)), levels of theory. The equilibrium structures, their relative stability, and the Transition State (TS) structures involved in the conformational interconversion pathways were analyzed. Aug-cc-pVTZ//B3LYP/6-311++G(d,p) and MP2/6-31G(d)//B3LYP/6-311++G(d,p) single point calculations predict a symmetric cis-cis-cis crown conformation as the energetically preferred form for this compound, which is

APA, Harvard, Vancouver, ISO, and other styles

7

Skov, Anders B., Martin A. B. Larsen, Mikkel B. Liisberg, Thorsten Hansen, and Theis I. Sølling. "Conformationally controlled ultrafast intersystem crossing in bithiophene systems." Physical Chemistry Chemical Physics 20, no. 19 (2018): 13412–18. http://dx.doi.org/10.1039/c8cp01419a.

Full text

Abstract:

Bithiophenes serve as model systems for polythiophenes used in solar cell applications and molecular electronics. Bithiophene has two major conformations, where the disfavored cis-conformation shows a higher rate of intersystem crossing.

APA, Harvard, Vancouver, ISO, and other styles

8

Mizutani, Tadashi, and Shigeyuki Yagi. "Linear tetrapyrroles as functional pigments in chemistry and biology." Journal of Porphyrins and Phthalocyanines 08, no. 03 (2004): 226–37. http://dx.doi.org/10.1142/s1088424604000210.

Full text

Abstract:

1,19,21,24-tetrahydro-1,19-bilindione is the framework of pigments frequently found in nature, which includes biliverdin IX α, phytochromobilin and phycocyanobilin. 1,19-bilindiones have unique features such as (1) photochemical and thermal cis-trans isomerization, (2) excited energy transfer, (3) chiroptical properties due to the cyclic helical conformation, (4) redox activity, (5) coordination to various metals, and (6) reconstitution to proteins. 1,19-bilindione can adopt a number of conformations since it has exocyclic three double bonds and three single bonds that are rotatable thermally

APA, Harvard, Vancouver, ISO, and other styles

9

Delgado, Antonio, José Miguel Garcia, David Mauleon, et al. "Synthesis and conformational analysis of 2-amino-1,2,3,4-tetrahydro-1-naphthalenols." Canadian Journal of Chemistry 66, no. 3 (1988): 517–27. http://dx.doi.org/10.1139/v88-088.

Full text

Abstract:

Synthesis and conformational analysis of several cis- and (or) trans-2-amino-1,2,3,4-tetrahydro-1-naphthalenols are described. Introduction of the nitrogen atom at the C(2) position of the starting tetralones 3 has been carried out through nitrosation followed by reduction of the intermediate hydroxyimino tetralone and (or) Neber rearrangement of the tosyloxy derivatives 7a–e. Stereoselective reduction of the C(1) carbonyl group of acetamidotetralones 5a–e or aminotetralones 8a–e afforded the corresponding acetamido or aminotetralols, respectively, of OH/N trans stereochemistry whereas an oppo

APA, Harvard, Vancouver, ISO, and other styles

10

Beierbeck, Helmut, George Kotovych, and Makiko Sugiura. "The conformations of prostacyclin and related prostaglandins." Canadian Journal of Chemistry 63, no. 5 (1985): 1143–49. http://dx.doi.org/10.1139/v85-194.

Full text

Abstract:

The conformations of prostacyclin, PGI2, and three of its analogues, 6R- and 6S-PGI1 and carbacyclin, were studied by high field 1H nmr spectroscopy. The cis-bicyclo- and cis-oxabicyclo[3.3.0]octane ring conformations were completely assigned. The minima for the pseudorotational conformations are observed at 7E/12E for PGI2, [Formula: see text] for 6R-PGI1, and 6E/11E for 6S-PGI1, and carbacyclin. The data indicate that each molecule adopts a narrow pseudolibrational range, if not a single conformation. The α- and ω-side chain conformations were characterized, but not unambiguously. Vicinal co

APA, Harvard, Vancouver, ISO, and other styles

11

Yang, Jing, Jing Chen, and Zibiao Li. "Structural Basis for the Structure–Activity Behaviour of Oxaliplatin and its Enantiomeric Analogues: A Molecular Dynamics Study of Platinum-DNA Intrastrand Crosslink Adducts." Australian Journal of Chemistry 69, no. 4 (2016): 379. http://dx.doi.org/10.1071/ch15624.

Full text

Abstract:

The discrimination of Pt-GG adducts by mismatch repair proteins, DNA damage-recognition proteins, and translation DNA polymerases was thought to be vital in determining the toxicity, efficacy, and mutagenicity of platinum anti-tumour drugs. Studies on cis-diammine-Pt-GG (from cisplatin and carboplatin) and trans-R,R-diaminocyclohexane (DACH)-Pt-GG indicated that these proteins recognized the differences in conformation and conformational dynamics of Pt-DNA complexes. However, the structural basis of enantiomeric DACH-Pt-GG forms is unclear. Molecular dynamics simulations results presented here

APA, Harvard, Vancouver, ISO, and other styles

12

de Araujo Oliveira, Alan Leone, Luiz Guilherme Machado de Macedo, Yuri Alves de Oliveira Só, João Batista Lopes Martins, Fernando Pirani, and Ricardo Gargano. "Nature and role of the weak intermolecular bond in enantiomeric conformations of H2O2–noble gas adducts: a chiral prototypical model." New Journal of Chemistry 45, no. 18 (2021): 8240–47. http://dx.doi.org/10.1039/d0nj06135b.

Full text

Abstract:

The role and nature of the weak intermolecular bond in the H<sub>2</sub>O<sub>2</sub>–noble gas enantiomeric conformations are presented. Charge transfer associated with the formation of a weak intermolecular hydrogen bond tends to stabilize the cis-barrier conformation.

APA, Harvard, Vancouver, ISO, and other styles

13

Chen, Ya Kun, and Yan Alexander Wang. "First-principles computational studies of the torsional potential energy surface of the sec-butyl radical." Canadian Journal of Chemistry 89, no. 12 (2011): 1469–76. http://dx.doi.org/10.1139/v11-109.

Full text

Abstract:

First-principles calculations were carried out to investigate the torsional potential energy surface (PES) of the sec-butyl radical. All the wave function methods employed predict a cis-like stable conformation with a dihedral angle of about 47° in addition to the trans-like global minimum conformation and a gauche conformation. However, most of the popular density functional approaches predict only the latter two local minima and lack the cis conformation that was experimentally observed. On the other hand, some density functional methods that incorporate the exact exchange and asymptotically

APA, Harvard, Vancouver, ISO, and other styles

14

Tavanaei, Leila, and Davood Nori-Shargh. "New Insights into the Origin of the cis-Configuration Preferences in 1,2-Dihaloethenes: The Importance of the Bonding Orbital Deviations." Australian Journal of Chemistry 71, no. 1 (2018): 1. http://dx.doi.org/10.1071/ch17219.

Full text

Abstract:

The origin of the preferences for the cis-configurations in 1,2-difluoroethene (1), 1,2-dichloroethene (2), and 1,2-dibromoethene (3) were explored by means of the G3MP2, LC-ωPBE and CCSD(T) methods with the 6–311+G** basis set on all atoms, and natural bond orbital interpretation. On the basis of the results obtained, the cis-configurations preferences decrease in going from compound 1 to compound 3. Effectively, the deletions of the hyperconjugative interactions from the Fock matrices of the cis- and trans-configurations of compound 1 lead to the increase of the trans-conformation stability

APA, Harvard, Vancouver, ISO, and other styles

15

Mohan, Madhan Kumar, Nikita Abraham, Rajesh R P та ін. "Structure and allosteric activity of a single-disulfide conopeptide from Conus zonatus at human α3β4 and α7 nicotinic acetylcholine receptors". Journal of Biological Chemistry 295, № 20 (2020): 7096–112. http://dx.doi.org/10.1074/jbc.ra119.012098.

Full text

Abstract:

Conopeptides are neurotoxic peptides in the venom of marine cone snails and have broad therapeutic potential for managing pain and other conditions. Here, we identified the single-disulfide peptides Czon1107 and Cca1669 from the venoms of Conus zonatus and Conus caracteristicus, respectively. We observed that Czon1107 strongly inhibits the human α3β4 (IC50 15.7 ± 3.0 μm) and α7 (IC50 77.1 ± 0.05 μm) nicotinic acetylcholine receptor (nAChR) subtypes, but the activity of Cca1669 remains to be identified. Czon1107 acted at a site distinct from the orthosteric receptor site. Solution NMR experimen

APA, Harvard, Vancouver, ISO, and other styles

16

Corne, Valeria, Ariel M. Sarotti, Carmen Ramirez de Arellano, Rolando A. Spanevello та Alejandra G. Suárez. "Experimental and theoretical insights in the alkene–arene intramolecular π-stacking interaction". Beilstein Journal of Organic Chemistry 12 (28 липня 2016): 1616–23. http://dx.doi.org/10.3762/bjoc.12.158.

Full text

Abstract:

Chiral acrylic esters derived from biomass were developed as models to have a better insight in the aryl–vinyl π-stacking interactions. Quantum chemical calculations, NMR studies and experimental evidences demonstrated the presence of equilibriums of at least four different conformations: π-stacked and face-to-edge, each of them in an s-cis/s-trans conformation. The results show that the stabilization produced by the π–π interaction makes the π-stacked conformation predominant in solution and this stabilization is slightly affected by the electron density of the aromatic counterpart.

APA, Harvard, Vancouver, ISO, and other styles

17

Chinnakali, K., D. Sudha, M. Jayagopi, R. Raghunathan, and Hoong-Kun Fun. "cis-4,4,10-Trimethyl-2-tosyl-1,2,3,3a,4,11b-hexahydro-11H-pyrrolo[3,4-c]pyrano[5,6-c]quinolin-11-one hemihydrate." Acta Crystallographica Section E Structure Reports Online 63, no. 11 (2007): o4489—o4490. http://dx.doi.org/10.1107/s1600536807053287.

Full text

Abstract:

The asymmetric unit of the title compound, C24H26N2O4S·0.5H2O, contains two independent molecules, A and B, with similar conformations, and a water molecule. The pyrrolidine ring adopts an envelope conformation in molecule A and a twist conformation in molecule B. In both molecules, the pyrrolidine and dihydropyran rings are cis-fused, and the dihydropyran ring has a half-chair conformation. Each of the independent molecules adopts a folded conformation, with the sulfonyl-bound benzene ring lying over the pyridinone ring. The two independent molecules, A and B, are linked together via C—H...O

APA, Harvard, Vancouver, ISO, and other styles

18

Chinnakali, K., D. Sudha, M. Jayagopi, R. Raghunathan, and Hoong-Kun Fun. "4,4,7,7-Tetramethyl-2-tosyl-2,3,3a,4,6,7,8,9-octahydro-1H-pyrrolo[3,4-c]pyrano[6,5-b]cyclohexan-9-one." Acta Crystallographica Section E Structure Reports Online 63, no. 11 (2007): o4436—o4437. http://dx.doi.org/10.1107/s1600536807052221.

Full text

Abstract:

The title compound, C22H29NO4S, crystallizes with three independent molecules, A, B and C, in the asymmetric unit. Each of the three independent molecules adopts a folded conformation, with the phenylsulfonyl group lying over the pyranocyclohexanone ring system, and with the pyrrolidine and dihydropyran rings cis-fused. In all three molecules, the pyrrolidine ring has a twist conformation and the dihydropyran ring is in a half-chair conformation. The cyclohexenone rings adopt envelope conformations, with the flap atom puckered towards the phenylsulfonyl group in molecule A, and away from that

APA, Harvard, Vancouver, ISO, and other styles

19

Rabenstein, Dallas L., and Yvon Theriault. "A nuclear magnetic resonance study of the formation and conformational equilibria of symmetrical and mixed disulfides of captopril." Canadian Journal of Chemistry 63, no. 1 (1985): 33–39. http://dx.doi.org/10.1139/v85-006.

Full text

Abstract:

The oxidation of captopril (CpSH, 1-(D-3-mercapto-2-methylpropanoyl)-1-proline) by glutathione disulfide (GSSG) via thiol/disulfide exchange to form, in the first step, CpSSG and GSH and, in the second step, CpSSCp and GSH, has been studied in aqueous solution by 1H nmr. Due to slow rotation around the amide bond(s) of CpSH and CpSSCp and of the captopril part of CpSSG, separate resonances are observed for the cis and trans conformations across these bonds. Conformational equilibrium constants were estimated as a function of pH for CpSH, CpSSCp, and CpSSG from the intensities of resonances for

APA, Harvard, Vancouver, ISO, and other styles

20

Bremer, J., and GL Mendz. "Comparison of Theoretical and Experimental Determinations of cis/trans Proline Isomer Ratios: Effect of Molecular Charge State." Australian Journal of Chemistry 42, no. 7 (1989): 1011. http://dx.doi.org/10.1071/ch9891011.

Full text

Abstract:

The resonances of the 1H and 13C n.m.r. spectra of the peptide Pro-Pro-Pro in aqueous solutions have been assigned to specific nuclei by employing one- and two-dimensional techniques and pH titrations. Minimum energy conformations of the tripeptide in different ionization states were estimated by conformational energy calculations with two effective dielectric constants. The cis/trans isomer ratios of the lowest energy conformers obtained for each set of conditions were compared to the isomer ratios measured from the 13C n.m.r. spectra of the peptide in the cationic, zwitterionic and anionic f

APA, Harvard, Vancouver, ISO, and other styles

21

Flores-Alamo, Marcos, Montserrat Benitez-Montelongo, Rafael Moreno-Esparza та Martin A. Iglesias-Arteaga. "(23S,25R)-3β,23-Dihydroxy-5-spirosten-3-yl acetate". Acta Crystallographica Section E Structure Reports Online 62, № 7 (2006): o2805—o2806. http://dx.doi.org/10.1107/s1600536806020265.

Full text

Abstract:

In the title compound, C29H44O5, the ester substituent in ring A is equatorial. The six-membered rings A and C have chair conformations and ring B has a half-chair conformation. The B/C and C/D ring junctions are trans, whereas the tetrahydrofuran ring E is cis-fused to the cyclopentane ring D. An intermolecular O—H...O hydrogen bond is observed.

APA, Harvard, Vancouver, ISO, and other styles

22

Ahmad, Manzoor, Shamsher Ali, Farzana Shaheen, Shazia Anjum, and M. Iqbal Choudhary. "14-Acetyl-20-ethyl-1,8-dihydroxy-16,18-dimethoxylycoctonine." Acta Crystallographica Section E Structure Reports Online 62, no. 4 (2006): o1428—o1430. http://dx.doi.org/10.1107/s1600536806008944.

Full text

Abstract:

The title compound (C25H39NO6), a polycyclic diterpenoid alkaloid, has been isolated from Delphinium roylei Munz. Two cis-fused ring junctions are observed between cyclohexane A and piperidine E rings and between cyclohexane B and cyclopentane C rings. Two trans-fused ring junctions involve cyclohexane A and cyclopentane B rings and also piperidine E and cyclopentane F rings. Cyclopentane ring F is in a twist conformation, while the other cyclopentane ring, C, forms an envelope conformation. Piperidine ring E is in a chair conformation, the two cyclohexane rings A and B adopt twist–boat confor

APA, Harvard, Vancouver, ISO, and other styles

23

Kotek, Jan, Pavel Vojtíšek, Ivana Císařová, Petr Hermann, and Ivan Lukeš. "Unusual cis/trans Isomerism in Octahedral Nickel(II) Complexes with 1,4,8,11-Tetraazacyclotetradecane-1,8-bis(methylphosphonic Acid) as a Ligand." Collection of Czechoslovak Chemical Communications 66, no. 2 (2001): 363–81. http://dx.doi.org/10.1135/cccc20010363.

Full text

Abstract:

Nickel(II) ion reacts with 1,4,8,11-tetraazacyclotetradecane-1,8-bis(methylphosphonic acid) (H4L1) at room temperature with formation of cis-[Ni(L1)]2- complex. The complex was crystallised in several forms in dependence on conditions of isolation (temperature, pH, solvent mixture). Crystal structures of cis-O,O-[Ni(H2L1)] (1), cis-O,O-[Ni(H2L1)]·2H2O (2), cis-O,O-[Ni(H3L1)]Cl·H2O (3) and cis-O,O-[Ni(H4L1)]Cl2·2H2O (4) were determined by X-ray diffraction. In all the compounds, Ni2+ is in octahedral cis-O1,O2-trans-N1,N8-cis-O1,N4-[Ni(L1)]2- (hereafter abbreviated as cis-O,O-[Ni(L1)]2-) arrang

APA, Harvard, Vancouver, ISO, and other styles

24

Perrott, Allyson L., and Donald R. Arnold. "The importance of conformation in the reactivity of radical cations. Changing configuration at saturated carbon centres." Canadian Journal of Chemistry 70, no. 1 (1992): 272–79. http://dx.doi.org/10.1139/v92-037.

Full text

Abstract:

Irradiation of an acetonitrile solution of cis 1-methyl-2-phenylcyclopentane (1bcis); 1,4-dicyanobenzene (2), an electron-accepting photosensitizer; and 2,4,6-collidine (3), a nonnucleophilic base, leads to configurational isomerization of the cyclopentane; the photostationary state lies > 99% in favour of the trans isomer. The mechanism proposed for this reaction involves formation of the radical cation of 1bcis by photoinduced electron transfer to the singlet excited state of 2, deprotonation of the radical cation assisted by the base 3, reduction of the resulting benzylic radical by the

APA, Harvard, Vancouver, ISO, and other styles

25

Fritzsche, H., J. Fink, N. Nücker, B. Scheerer, and G. Leising. "Momentum-dependent dielectric function of the cis-transoid conformation of cis-polyacetylene." Physical Review B 40, no. 11 (1989): 8033–36. http://dx.doi.org/10.1103/physrevb.40.8033.

Full text

APA, Harvard, Vancouver, ISO, and other styles

26

Cagardová, Denisa, Peter Poliak, and Vladimír Lukeš. "Quantum-chemical study of molecular structure and relative stability of trans and cis isomers of model anilide derivatives." Acta Chimica Slovaca 10, no. 2 (2017): 144–51. http://dx.doi.org/10.1515/acs-2017-0024.

Full text

Abstract:

AbstractDerivatives of anilide were studied systematically by the density functional theory (DFT) using the B3LYP hybrid functional and the 6-311+G(3df,2p) basis set. Characteristic frequencies of N-H and C=O stretching modes for cis and trans conformers distinguishing were compared with available experimental and theoretical data. Effect of substitution in ortho position and acidic residue group is discussed with respect to the bond length changes in the aromatic ring and aromaticity indexes. Energy differences between cis and trans conformations allow estimating the effect of intramolecular

APA, Harvard, Vancouver, ISO, and other styles

27

Lavillette, Dimitri, Alessia Ruggieri, Bertrand Boson, Marielle Maurice, and François-Loïc Cosset. "Relationship between SU Subdomains That Regulate the Receptor-Mediated Transition from the Native (Fusion-Inhibited) to the Fusion-Active Conformation of the Murine Leukemia Virus Glycoprotein." Journal of Virology 76, no. 19 (2002): 9673–85. http://dx.doi.org/10.1128/jvi.76.19.9673-9685.2002.

Full text

Abstract:

ABSTRACT Envelope glycoproteins (Env) of retroviruses are trimers of SU (surface) and TM (transmembrane) heterodimers and are expressed on virions in fusion-competent forms that are likely to be metastable. Activation of the viral receptor-binding domain (RBD) via its interaction with a cell surface receptor is thought to initiate a cascade of events that lead to refolding of the Env glycoprotein into its stable fusion-active conformation. While the fusion-active conformation of the TM subunit has been described in detail for several retroviruses, little is known about the fusion-competent str

APA, Harvard, Vancouver, ISO, and other styles

28

Delgado, Antonio, David Mauleon, Cristina Minguillon, Miguel Feliz, Miquel A. Pericas, and Antoni Riera. "Stereochemical assignment of 2-amino-1,2,3,4-tetrahydro-1-naphthalenols via oxazolidin-2-one derivatives." Canadian Journal of Chemistry 65, no. 4 (1987): 868–72. http://dx.doi.org/10.1139/v87-146.

Full text

Abstract:

The stereochemical assignment of cis- and trans-2-amino-1,2,3,4-tetrahydro-1-naphthalenols (1) can be performed by means of their conformationally restrained tricyclic tetrahydronaphtho[2,1-d]oxazol-2-one derivatives 2–6. Thus, 1H and 13C nuclear magnetic resonance data of compounds 2–6 reveal differences between the cis and trans stereoisomers that are independent of the nature and number of the aromatic substituents. Conformational analysis of compounds 2–6 has been performed from the LAOCOON/3 analysis of their nuclear magnetic resonance spectra and MNDO theoretical results, through the use

APA, Harvard, Vancouver, ISO, and other styles

29

Mak, Melody L., Salvatore J. Salpietro, R. Daniel Enriz, and Imre G. Csizmadia. "An exploratory ab initio study on the conformations of ethylguanidine in its neutral [CH3-CH2-NH-C(=NH)NH2] and protonated [CH3-CH2-NH-C(NH2)2] forms." Canadian Journal of Chemistry 78, no. 5 (2000): 626–41. http://dx.doi.org/10.1139/v00-065.

Full text

Abstract:

To explore the conformation intricacies of the guanidine group in the arginine side chain, ab initio computations have been carried out with ethylguanidine and the ethyl guanidinium ion. HF computations have been performed using 3-21G and 6-31G basis sets and DFT calculations were carried out at the B3LYP/6-31G(d) level of theory. The ethyl guanidinium ion has a single isomer due to its internal symmetry, although this structure has at least three conformations. However, several structures were found and optimized for ethylguanidine, involving the endo- and exo- orientation of the lone NH and

APA, Harvard, Vancouver, ISO, and other styles

30

Mó, Otilia, José L. G. De Paz, Manuel Yáñez, et al. "A molecular orbital study of the conformation (inversion and rotational barriers) and electronic properties of sulfamide." Canadian Journal of Chemistry 67, no. 12 (1989): 2227–36. http://dx.doi.org/10.1139/v89-347.

Full text

Abstract:

Abinitio calculations have been used to study the conformational potential surface of sulfamide, by considering the S—N bond rotations and the nitrogen inversion processes. The lowest energy conformation (b) is found for a cis–trans arrangement of the amino groups, although conformations with cis–cis (a), trans–trans (c), and near staggered (c′) arrangements lie close in energy. Nitrogen inversion barriers are very low, and consequently one may expect forms b and c′ to be the only ones present in the gas phase. Conformer a is very polar, its dipole moment being twice that of b, so it may be fa

APA, Harvard, Vancouver, ISO, and other styles

31

Yamato, Takehiko, Koji Fujita, Keigo Futatsuki, and Hirohisa Tsuzuki. "Medium-sized cyclophanes. Part 53.1 Synthesis and conformational studies, and photoinduced cyclization of syn-[n.2]metacyclophanenes." Canadian Journal of Chemistry 78, no. 8 (2000): 1089–99. http://dx.doi.org/10.1139/v00-110.

Full text

Abstract:

A series of [n.2]metacyclophanenes (3) and (6) were prepared in good yields by a McMurry cyclization of 1,n-bis(3-acetyl-4-methoxyphenyl)alkanes (2) and 1,3-bis(3-formyl-4-methoxyphenyl)propane (5), respectively. Compounds 3b, 3c exist in the syn-conformation due to the steric repulsion between the methyl groups at the ethano bridge and the methoxy groups at the aromatic rings while compound 6 prefers the anti-conformation typical of [3.2]metacyclophanes. The assignment of syn-conformations has been confirmed by 1H NMR analyses and X-ray diffraction studies. Photoinduced transannular cyclizati

APA, Harvard, Vancouver, ISO, and other styles

32

Arif Tawfeeq, Nabeel, Huey Chong Kwong, Mohamed Ibrahim Mohamed Tahir, and Thahira B. S. A. Ravoof. "Crystal structure and Hirshfeld surface analysis of a conformationally unsymmetrical bischalcone: (1E,4E)-1,5-bis(4-bromophenyl)penta-1,4-dien-3-one." Acta Crystallographica Section E Crystallographic Communications 75, no. 6 (2019): 774–79. http://dx.doi.org/10.1107/s2056989019006480.

Full text

Abstract:

In the title bischalcone, C17H12Br2O, the olefinic double bonds are almost coplanar with their attached 4-bromophenyl rings [torsion angles = −10.2 (4) and −6.2 (4)°], while the carbonyl double bond is in an s-trans conformation with with respect to one of the C=C bonds and an s-cis conformation with respect to the other [C=C—C=O = 160.7 (3) and −15.2 (4)°, respectively]. The dihedral angle between the 4-bromophenyl rings is 51.56 (2)°. In the crystal, molecules are linked into a zigzag chain propagating along [001] by weak C—H...π interactions. The conformations of related bischalcones are su

APA, Harvard, Vancouver, ISO, and other styles

33

Obregón-Mendoza, Marco A., Imilla I. Arias-Olguín, William Meza-Morales, et al. "Expected and Unexpected Products in Half Curcuminoid Synthesis: Crystal Structures of But-3-en-2-ones and 3-Methylcyclohex-2-enones." Crystals 11, no. 4 (2021): 404. http://dx.doi.org/10.3390/cryst11040404.

Full text

Abstract:

The expected (E)-but-3-en-2-ones compounds I and II (half curcuminoids) were obtained by the Claisen–Schmidt reaction between aldehydes 3,4-dimethoxybenzaldehyde or 4-nitrobenzaldehyde with acetone. Concomitantly, 3-methylcyclohex-2-enones compounds III and IV arose from an unexpected reaction of but-3-en-2-ones in the cascade reaction of a Michael-type addition of a second molecule of acetone followed by Robinson annulation under strong basic conditions. Both enones exhibit the (E)-configuration, compound I displays s-trans conformation, whereas compound II exhibits conformational disorder as

APA, Harvard, Vancouver, ISO, and other styles

34

Wang, Yan-Qin, and Jia-Bao Weng. "cis-Cyclohexane-1,4-dicarboxylic acid." Acta Crystallographica Section E Structure Reports Online 65, no. 6 (2009): o1293. http://dx.doi.org/10.1107/s1600536809016110.

Full text

Abstract:

In the title compound, C8H12O4, the two carboxyl groups are on the same side of the cyclohexane ring and the ring adopts a chair conformation. Adjacent molecules related by an inversion centre are linked by pairs of O—H...O hydrogen bonds, forming a zigzag chain along [1\overline{1}\overline{1}].

APA, Harvard, Vancouver, ISO, and other styles

35

Hellmund, KA, SG Pyne, BW Skelton, and AH White. "Chiral Sulfur Compounds. XVIII. Structure and Conformation of Methyl (E,S*)-3-Phenyl-2-(phenylsulfinyl)propenoate." Australian Journal of Chemistry 45, no. 11 (1992): 1923. http://dx.doi.org/10.1071/ch9921923.

Full text

Abstract:

The X-ray structural analysis of the title compound shows that the s-cis conformation is favoured in the solid state. This conformation is consistent with circular dichroism studies in methanol solution.

APA, Harvard, Vancouver, ISO, and other styles

36

Elert, Mark L., C. T. White, and J. W. Mintmire. "Conformation and Electronic Properties of Helical Cis-Polyacetylene." Molecular Crystals and Liquid Crystals 125, no. 1 (1985): 329–35. http://dx.doi.org/10.1080/00268948508080112.

Full text

APA, Harvard, Vancouver, ISO, and other styles

37

Han, Xiang-Yu, Ming-An Wang, Xiao-Mei Liang, and Dao-Quan Wang. "Synthesis and conformation of cis-1,2-disubstituted cyclododecene." Chinese Journal of Chemistry 22, no. 6 (2010): 563–67. http://dx.doi.org/10.1002/cjoc.20040220614.

Full text

APA, Harvard, Vancouver, ISO, and other styles

38

Tang, Hong-Jin, Xiao-Feng Yuan, Hai-Yan Tian, Li-Jun Ruan, and Ren-Wang Jiang. "Deacetylcinobufalactam monohydrate." Acta Crystallographica Section E Structure Reports Online 70, no. 6 (2014): o651—o652. http://dx.doi.org/10.1107/s1600536814010046.

Full text

Abstract:

The title compound, C24H33NO4·H2O, the reaction product of deacetylcinobufagin with ammonium acetate, consists of three cyclohexane rings (A,BandC), one five-membered ring (D), one six-membered lactone ring (E) and an epoxide ring (F). The stereochemistry of the ring junctures areA/B cis,B/C trans,C/D cisandD/F cis. Cyclohexane ringsA,BandChave normal chair conformations. The five-membered ringDadopts an envelope conformation (with the C atom bearing the lactone ring as the flap) and the lactone ringEis planar. In the crystal, hydroxy and water O—H...O and amine N—H...O hydrogen bonds involvin

APA, Harvard, Vancouver, ISO, and other styles

39

Liedtke, M., A. H. Saleck, J. Behrend, G. Winnewisser, R. Klünsch, and J. Hahn. "Rotational Spectrum of cis-HS3D." Zeitschrift für Naturforschung A 47, no. 10 (1992): 1091–93. http://dx.doi.org/10.1515/zna-1992-1014.

Full text

Abstract:

AbstractThe rotational spectrum of HS3D in the vibrational ground state has been measured in the frequency range between 75 and 293 GHz. Up to now, about 180 Q-, 30 P-, and 70 R-branch c-type transitions have been identified. The preliminary rotational constants of the species observed support the cis-conformation established earlier from the H2S3 rotational spectrum.

APA, Harvard, Vancouver, ISO, and other styles

40

Calinaud, Evelyne, Jean-Claude Gramain, and Jean-Charles Quirion. "Determination of cis-methyldecalone and cis-methylhydrindanone conformation by proton nuclear magnetic resonance." Journal of the Chemical Society, Perkin Transactions 2, no. 7 (1987): 921. http://dx.doi.org/10.1039/p29870000921.

Full text

APA, Harvard, Vancouver, ISO, and other styles

41

Broeders, Niek L. H. L., Arthur P. van der Heiden, Leo H. Koole, Jan A. Kanters, and Arie Schouten. "2′-O-Methyl-cis-adenosine 3′,5′-cyclic methyl monophosphate, a new model system for cAMP. Aspects of structure and reactivity." Canadian Journal of Chemistry 71, no. 6 (1993): 855–63. http://dx.doi.org/10.1139/v93-114.

Full text

Abstract:

This study is focussed on 2′-O-methyl-cis-adenosine 3′,5′-cyclic methyl monophosphate (cis-4; cis describes the relationship between OMe (bound to phosphorus) and the adenine base), which is regarded a model for enzyme-bound cyclic adenosine monophosphate (cAMP). In this complex the negative phosphate charge is shielded in part via complexation with cationic sites on the enzyme surface. We report synthesis, crystal structure, solution conformation (400 MHz 1H NMR), and kinetic-mechanistic aspects of the alkaline hydrolysis of cis-4. The methanol solvate of cis-4 crystallizes in the orthorhombi

APA, Harvard, Vancouver, ISO, and other styles

42

Childs, Ronald F., Mailvaganam Mahendran, Christopher Blackburn, and Gregory Antoniadis. "The importance of ground state conformation in the photoisomerizations of protonated enones." Canadian Journal of Chemistry 66, no. 6 (1988): 1355–58. http://dx.doi.org/10.1139/v88-219.

Full text

Abstract:

The conformations of several protonated enones have been determined by low temperature 13C nuclear magnetic resonance spectroscopy. Information on the ground state conformation has been used to understand the differences in the photochemistry of these systems. Photoisomerizations of 4 and 5 have been examined. In the case of 4, irradiation leads only to the formation of the Z isomer 16; protonated dihydrofuran 13 was not observed. In the case of 5, both the Z isomer 17 and protonated dihydrofuran 14 were observed. The protonated dihydrofuran 14 was produced from the start of the reaction. It i

APA, Harvard, Vancouver, ISO, and other styles

43

Bringmann, Gerhard, Doris Feineis, Wael Saeb, Christiana Hesselmann, Eva-Maria Peters, and Karl Peters. "Endogenous Alkaloids in Man, Part 33. Dimethyl (2S,4S)-and (2R,4S)-5,5-Dimethyl-1,3-thiazolidine-2,4-dicarboxylates, Two Diastereomeric Glyoxylate-Derived Heterocycles." Zeitschrift für Naturforschung B 55, no. 2 (2000): 208–12. http://dx.doi.org/10.1515/znb-2000-0213.

Full text

Abstract:

Both title compounds were obtained in stereochemically pure form by refluxing 5,5-dim ethyl-1 ,3-thiazolidine-2,4-dicarboxylic acid (3) with methanolic HCl, followed by a separation of the two diastereomers 4a and 4b on silica gel. The X-ray structure analyses of these stereoisomers confirm the relative configuration to be cis for 4a and trans for 4b with respect to the two carboxymethyl substituents at C(2) and C(4). For both molecules, an envelopetype conformation of the thiazolidine ring was found with C(5)-S(1)-C(2)-N(3) being located in a plane showing a small ring torsion angle of -11.2°

APA, Harvard, Vancouver, ISO, and other styles

44

Xu, Yinxiang, Yujia Zhang, Steven Wang, Junbo Xu, and Chao Yang. "Conformation-induced separation of 3-chloropropene from 1-chloropropane through nanoporous monolayer graphenes." Physical Chemistry Chemical Physics 21, no. 9 (2019): 5170–77. http://dx.doi.org/10.1039/c9cp00137a.

Full text

Abstract:

Conformation-induced separation shows that C<sub>3</sub>H<sub>5</sub> twisting to the pore preferred cis-conformation with a lower energy penalty than C<sub>3</sub>H<sub>7</sub> can cross the nanopore.

APA, Harvard, Vancouver, ISO, and other styles

45

Clegg, Jack K., James R. Cochrane, Nima Sayyadi, Danielle Skropeta, Peter Turner, and Katrina A. Jolliffe. "Solid-State and Solution-Phase Conformations of Pseudoproline-Containing Dipeptides." Australian Journal of Chemistry 62, no. 7 (2009): 711. http://dx.doi.org/10.1071/ch09151.

Full text

Abstract:

The conformations of 14 threonine-derived pseudoproline-containing dipeptides (including four d-allo-Thr derivatives) have been investigated by NMR. In solution, the major conformer observed for all dipeptides is that in which the amide bond between the pseudoproline and the preceding amino acid is cis. For dipeptides in which the N-terminus is protected, the ratio of cis- to trans-conformers does not depend significantly on the side chain of the N-terminal amino acid, or the stereochemistry of the Thr residue. However, for dipeptides bearing a free N-terminus, there are significant difference

APA, Harvard, Vancouver, ISO, and other styles

46

Qin, Linlin, Linling Li, Ye Sha, et al. "Conformational Transitions of Polymer Chains in Solutions Characterized by Fluorescence Resonance Energy Transfer." Polymers 10, no. 9 (2018): 1007. http://dx.doi.org/10.3390/polym10091007.

Full text

Abstract:

The critical overlap concentration C* is an important concept in polymer solutions and is defined as the boundary between dilute and semidilute regimes. In this study, the chain conformational changes of polystyrene (PS) with both high (Mn = 200,000 Da) and low (Mn = 13,000 Da) molecular weights in cis-decalin were compared by intrachain fluorescence resonance energy transfer (FRET). The random labeling of donor and acceptor chromophores strategy was employed for long PS chains, whereas chain-end labeling was used for short PS chains. By monitoring the spectroscopic intensity ratio between acc

APA, Harvard, Vancouver, ISO, and other styles

47

Tutughamiarso, Maya, and Ernst Egert. "Cocrystals of 5-fluorocytosine. II. Coformers with variable hydrogen-bonding sites." Acta Crystallographica Section B Structural Science 68, no. 4 (2012): 444–52. http://dx.doi.org/10.1107/s0108768112029977.

Full text

Abstract:

Two flexible molecules, biuret and 6-acetamidouracil, were cocrystallized with 5-fluorocytosine to study their conformational preferences. In the cocrystal with 5-fluorocytosine (I), biuret exhibits the same conformation as in its hydrate. In contrast, 6-acetamidouracil can adopt two main conformations depending on its crystal environment: in crystal (II) the trans form characterized by an intramolecular hydrogen bond is observed, while in the cocrystal with 5-fluorocytosine (III), the complementary binding induces the cis form. Three cocrystals of 6-methylisocytosine demonstrate that compleme

APA, Harvard, Vancouver, ISO, and other styles

48

Bláha, Karel, Miloš Buděšínský, Ivo Frič, Jan Pospíšek, and Jindřich Symerský. "Conformation of diastereoisomeric cyclo(neopentylglycyl-prolyls): NMR, X-ray, and CD studies." Collection of Czechoslovak Chemical Communications 52, no. 9 (1987): 2295–308. http://dx.doi.org/10.1135/cccc19872295.

Full text

Abstract:

Conformation of diastereoisomeric cyclo(L-neopentylglycyl-L-prolyl) (IV) and cyclo(D-neopentylglycyl-L-prolyl) (VIII) in solution was studied by 1H and 13C NMR spectroscopy. Both compounds have approximately the same conformation of the bicyclic moiety in which the 2,5-piperazinedione ring exists in the boat form with pseudoaxial proline H(α) atom, and the proline ring is in the C(γ)-exo conformation. Rotation of the neopentyl side chain is markedly hindered. In the trans-derivative VIII the side chain occupies a pseudoaxial position with staggered rotamer about the C(α)-C(β) bond, the tert-bu

APA, Harvard, Vancouver, ISO, and other styles

49

Malak, Muhammad H., Roger A. Lalancette, and Hugh W. Thompson. "(−)-cis-1-Acetyl-3-ethynyl-2,2-dimethylcyclobutane." Acta Crystallographica Section E Structure Reports Online 63, no. 3 (2007): o1412—o1414. http://dx.doi.org/10.1107/s1600536807007386.

Full text

Abstract:

The title compound, C10H14O, adopts a conformation typical of cis-1,3-disubstituted cyclobutanes, with the ring flexed out of planarity so that the substituents are maximally separated. The two intermolecular C—H...O=C close contacts found include one involving the acetylenic H atom.

APA, Harvard, Vancouver, ISO, and other styles

50

Ospanov, M. A., M. Zh Turmukhanova, Zh A. Abilov, and Peter Langer. "Stereochemical Peculiarities of the Products of Condensation of Piperidine-4-one with Aromatic Aldehydes." Eurasian Chemico-Technological Journal 18, no. 2 (2016): 111. http://dx.doi.org/10.18321/ectj431.

Full text

Abstract:

<p>This paper presents the results of investigations on conformation peculiarities of the condensation products of piperidine-4-ones containing arylidene, hydroxyarylmethyl as well as both arylidene and hydroxyarylmethyl substituents. Synthesized α, β-unsaturated ketones can be used to investigate conformation of cycles fixing a conjugated system of carbonyl and double bonds. Synthesis of α, β-unsaturated piperidine-4-ones was carried out according to the reaction of Claisen-Schmidt by condensation of piperidine-4-ones with aromatic aldehydes. The reaction was carried out in methanol med

APA, Harvard, Vancouver, ISO, and other styles

We offer discounts on all premium plans for authors whose works are included in thematic literature selections. Contact us to get a unique promo code!