Temperature-dependent intensity anomalies in amino acid esters: weak hydrogen bonds in protected glycine, alanine and valine
| Autor: | Katharina E. Otto, Corey A. Rice, Thorsten Stafforst, Susanne Hesse, Martin A. Suhm, Tobias N. Wassermann, Ulf Diederichsen |
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| Jazyk: | angličtina |
| Rok vydání: | 2011 |
| Předmět: |
Stereochemistry
Glycine General Physics and Astronomy 010402 general chemistry Spectrum Analysis Raman 01 natural sciences symbols.namesake Valine Spectroscopy Fourier Transform Infrared Physical and Theoretical Chemistry chemistry.chemical_classification Alanine Quantitative Biology::Biomolecules Raman spectroscopy amino acid esters dispersion interactions 010405 organic chemistry Hydrogen bond Temperature Esters Hydrogen Bonding 0104 chemical sciences 3. Good health Amino acid Crystallography chemistry Intramolecular force symbols Dispersion (chemistry) Chirality (chemistry) |
| Popis: | Esters of glycine, alanine and valine are investigated by FTIR and Raman spectroscopy in supersonic jets as gas phase model systems for the neutral peptide N-terminus. The NH-stretching vibrations exhibit very large temperature- and substitution-dependent intensity anomalies which are related to weak, bifurcated intramolecular hydrogen bonds to the carbonyl group. Comparison to theory is only satisfactory at low temperature. Spectral NH aggregation shifts are small or even negligible and the associated IR intensity is remarkably low. In the case of valine, chirality recognition effects are nevertheless detected and rationalized. Comparison to quantum-chemical calculations for dimers shows that dispersion interactions are essential. It also rules out cooperative hydrogen bond topologies and points at deficiencies in standard harmonic treatments with the linear dipole approximation. peerReviewed |
| Databáze: | OpenAIRE |
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