Benjamin Böttcher

Technical University Darmstadt, Darmstadt, Hesse, Germany

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Publications (4)28.25 Total impact

  • Benjamin Böttcher · Christina M. Thiele ·

    Encyclopedia of Magnetic Resonance, 03/2012; , ISBN: 0470034599
  • Andreas Marx · Benjamin Böttcher · Christina M Thiele ·
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    ABSTRACT: Residual dipolar couplings (RDCs) have recently become increasingly important in organic structure determination due to their unique information content. One main limitation for the use of RDCs in organic compounds is the orientation that needs to be induced to be able to measure RDCs. So far, there are very few possibilities to modulate the orientational properties of organic solutes and even less when chiral media are considered. Based on our recent findings that the critical concentration of the liquid-crystalline phase of homopolypeptides depends on their molecular weight, we sought for further ways to modulate the orienting properties. We were especially interested in seeing whether we could not only influence the induced degree of orientation, but whether we could also change the solute's preferred orientation and even enhance enantiodifferentiation. We thus tried different aprotic and protic additives and were successful in all of the above-mentioned aspects by using CCl(4) as the additive. Furthermore, we consider DMSO to be a very useful additive. The LC phase of low MW poly(gamma-benzyl-L-glutamate) (PBLG) is usually unstable when DMSO is added. The high MW PBLG used in this study, however, remained stable up to a DMSO/CDCl(3) ratio of 1:2. By using this combination of solvents, the alignment of the two enantiomers of a compound, which is insoluble in CDCl(3), namely, the HCl salt of a tryptophane ester, was possible leading to high-quality spectra. The two enantiomers of the tryptophane ester showed different couplings, thus indicating that enantiodifferentiation is taking place. Thus we were able to modulate the orienting properties (degree of orientation, preferred orientation and enantiodifferentiation) of PBLG by using additives and to increase the accessible solvent and solute range significantly.
    Chemistry - A European Journal 12/2009; 16(5):1656-63. DOI:10.1002/chem.200902287 · 5.73 Impact Factor
  • Benjamin Böttcher · Volker Schmidts · Jevgenij A Raskatov · Christina M Thiele ·
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    ABSTRACT: Chemical Equation Presentation Hide and seek! The reactive intermediate in the title reaction has eluded conventional structure determination for years. With the help of residual dipolar couplings the conformation in solution could be determined (see picture). The sensitive intermediate was aligned in a liquid-crystalline phase containing poly(Y-benzyl-L-glutamate), and the orientation of the ligands was determined through local order tensors.
    Angewandte Chemie International Edition 11/2009; 49(1):205-9. DOI:10.1002/anie.200903649 · 11.26 Impact Factor
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    ABSTRACT: Mission possible! The motional averaging of NMR spectroscopic data complicates the determination of conformation and relative configuration in flexible organic molecules. Two alternative routes are discussed for the treatment of conformational equilibrium in a moderately flexible compound (see the superposition of the two conformers of the butyrolactone studied) when residual dipolar couplings are used.
    Angewandte Chemie International Edition 08/2009; 48(36):6708-12. DOI:10.1002/anie.200902398 · 11.26 Impact Factor

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