Rotational isomerism

Abraham, Raymond J.; Cavalli, L.; Pachler, K.G.R.

doi:10.1080/00268976600101281

Cited by 151 publications

(30 citation statements)

References 24 publications

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“…NMR is the experimental tool of choice to explore conformational properties, especially of flexible small molecules in solution [55][56][57] . Interpretation of NMRderived structural parameters in combination with molecular modeling usually offers a view of the accessible conformations to ligands.…”

Section: Determination Of Solution Conformations Of the Uncomplexed Lmentioning

confidence: 99%

The Tubulin Binding Mode of MT Stabilizing and Destabilizing Agents Studied by NMR

Sánchez-Pedregal

Griesinger

2008

Topics in Current Chemistry

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Tubulin is a fascinating molecule that forms the cytoskeleton of the cells and plays an important role in cell division and trafficking of molecules. It polymerizes and depolymerizes in order to fulfill this biological function. This function can be modulated by small molecules that interfere with the polymerization or the depolymerization. In this article, the structural basis of this behavior is reviewed with special attention to the contribution of NMR spectroscopy. Complex structures of small molecules that bind to tubulin and microtubules will be discussed. Many of them have been determined using NMR spectroscopy, which proves to be an important method in tubulin research.

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Section: Determination Of Solution Conformations Of the Uncomplexed Lmentioning

confidence: 99%

The Tubulin Binding Mode of MT Stabilizing and Destabilizing Agents Studied by NMR

Sánchez-Pedregal

Griesinger

2008

Topics in Current Chemistry

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“…5 (ref. 9), where E, E,, and E, are the dielectric constants of solvent, solute, and solution, respectively, and V , and V , the volumes of solvent and solute. It is seen that with increasing polarity of the solution p, decreases from about 0.42 to 0.35, p, increases from 0.03 to 0.1 1, whereas p, and p, remain approximately constant over the solvent range at ca.…”

Section: Resultsmentioning

confidence: 99%

“…14. This program and the subroutine which determines the vapor phase energies were tested by the recalculation of literature values (9,11) and produced the same results. In the calculations of E, for 1, dipole moments of 1.8 D for the C-Br bonds (la) entailed too high a sensitivity to changes in solvent polarity.…”

Section: (3) Four-bond Couplingsmentioning

confidence: 99%

The Conformational Equilibrium of 1,2,3-Tribromopropane in Solution

Ernst¹,

Schaefer²

1973

Can. J. Chem.

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The p.m.r. spectra of dilute solutions of 1,2,3-tribromopropane in carbon tetrachloride, acetonitrile, and dimethylsulfoxide as well as of the neat compound are examined. From the three-and four-bond spin-spin coupling constants and from a comparison between observed and calculated dipole moments it is concluded that in nonpolar solvents the title compound exists preferably in the enantiomeric conformations a and i. In polar solvents other rotamers contribute to the equilibrium but still seem to play only a minor role. Semiempirical calculations of conformational energies rule out contributions to the conformational equilibrium from rotamers having (1 :3) bromine-bromine interactions, but otherwise are only in moderate agreement with experiment.Les spectres r.m.p. de solutions dilukes de tribromo-1,2,3 propane dans le tktrachlorure de carbone, I'acCtonitrile, et le dimethylsulfoxide aussi bien que ceux du composk pur ont etC etudiks. A partir des constantes de couplage spin-spin a trois et a quatre liaisons et a partir d'une comparaison entre les moments dipolaires calcul6s et observes, on a conclu au fait que dans des solvants non-polaires, le compose etudie existe preferentiellement dans les conformations CnantiomCriques a et i. Dans les solvants polaires, les autres rotameres contribuent a I'equilibre mais ne jouent, meme la, qu'un rBle mineur. Des calculs semiempiriques des energies conformationnelles refutent les contributions a I'equilibre conformationnel des rotameres possedant des interactions brome-brome (1 :3), mais autrement ceux-ci ne sont qu'en accord partiel seulement avec I'expkrience.[Traduit par le journal]Can. J. Chem., 51. 565 (1973)

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“…We have shown that relative rotamer energy levels for 1-phenyl-l,2-dibromoethane can be correctly deduced from changes of vicinal coupling constants with E and that reasonable values of relative rotamer energy levels for 1-phenyl-l,2-dibromopropanes can be deduced from the variation of vicinal coupling constants with E and temperature (9). However, this approach will only be valid if the compounds investigated obey the electrostatic theory (5). I n order to test the limits of applicability of the theory to more complex substituted ethanes, we have extended our investigation to include a large number of tetra-substituted ethanes, including 1-phenyl-l,2,2-trihaloethanes, 1-phenyl-1,2-dichloropropanes and 1,1,2-trihalopropanes.…”

Section: Introduction Gas Phase Energy Differences Are Generally Notmentioning

confidence: 95%

Effect of Solvent Upon the Vicinal Proton Coupling Constants of Complex Substituted Ethanes. II. Anomalous Results for 1-Phenyl-1,2,2-trihaloethanes

Reynolds¹,

Wood²

1971

Can. J. Chem.

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The n.m.r. spectra of 11 tetra-substituted ethanes have been obtained in a number of solvents. Changes in the vicinal coupling constants of 1-phenyl-l,2,2-trihaloethanes with solvent do not fit the electrostatic model for solvent effects. It is concluded that the theory breaks down because solute-solvent hydrogen bonding specifically favors the trans rotamers of these compounds. The conditions under which the theory would be expected to break down are also discussed in more general terms.Les spectres r.m.n. de 11 Cthanes tetra-substitub ont CtC obtenus dans un certain nombre de solvants. Des changements, avec le solvant, des constantes de couplage vicinales des phCny1-1 trihalo-1,2,2 ethanes ne peuvent Ctre accomodCs avec le modele Clectrostatique des effets de solvant. I1 en est conclu que la theorie ne tient pas parce que des ponts hydrogenes entre le solvant et le solute favorisent le rotamere trans de ces composes. Les conditions oh la thCorie ne serait pas approprite sont aussi discutkes en termes plus gCnCraux.

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Rotational isomerism

Cited by 151 publications

References 24 publications

The Tubulin Binding Mode of MT Stabilizing and Destabilizing Agents Studied by NMR

The Tubulin Binding Mode of MT Stabilizing and Destabilizing Agents Studied by NMR

The Conformational Equilibrium of 1,2,3-Tribromopropane in Solution

Effect of Solvent Upon the Vicinal Proton Coupling Constants of Complex Substituted Ethanes. II. Anomalous Results for 1-Phenyl-1,2,2-trihaloethanes

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