Journal ArticleDOI
The shape of beta-alanine.
M. Eugenia Sanz,Alberto Lesarri,M. Isabel Pena,Vanesa Vaquero,Vanessa Cortijo,Juan C. López,José L. Alonso +6 more
Reads0
Chats0
TLDR
The high sensitivity of the experiment has allowed us to detect for the first time a conformer uniquely stabilized by an n-pi* hyperconjugative interaction between the nucleophile N: of the amino group and the pi* orbital at the carbonyl group.Abstract:
The combination of Fourier transform microwave spectroscopy in a pulsed supersonic jet with laser ablation has made beta-alanine amenable to a structural study in the gas phase. Two new conformers of beta-alanine have been identified together with the two previously observed by McGlone and Godfrey [J. Am. Chem. Soc. 1995, 117, 1043]. The comparison between the experimental rotational and 14N nuclear quadrupole coupling constants and those calculated ab initio provide a definitive test for molecular structures and confirm unambiguously the identification of all conformers. For the two most abundant conformers, an intramolecular hydrogen bond between the amino group and carbonyl oxygen (N-H...O=C) is established, and the COOH adopts a cis-COOH configuration. The next conformer in order of abundance presents an O-H...N intramolecular hydrogen bond with a trans configuration for the COOH group. The high sensitivity of the experiment has allowed us to detect for the first time a conformer uniquely stabilized by an n-pi* hyperconjugative interaction between the nucleophile N: of the amino group and the pi* orbital at the carbonyl group. Partial conformational relaxation has been observed in the supersonic expansion.read more
Citations
More filters
Journal ArticleDOI
The n→π* Interaction
TL;DR: The carbonyl group holds a prominent position in chemistry and biology not only because it allows diverse transformations but also because it supports key intermolecular interactions, including hydrogen bonding, in what is termed an n→π* interaction, which is likely to play an important role in dictating protein structure.
Journal ArticleDOI
Competing Intramolecular vs. Intermolecular Hydrogen Bonds in Solution
TL;DR: The present review surveys the in-solution competition of the conformations with intramolecular vs. intermolecular hydrogen bonds for different types of small organic molecules and considers the solvent effects on the stability of simple dimeric systems as revealed from molecular dynamics simulations or on the basis of the calculated potential of mean force curves.
Journal ArticleDOI
Seven conformers of L-threonine in the gas phase: a LA-MB-FTMW study.
TL;DR: The rotational and nuclear quadrupole coupling constants extracted from the analysis of the rotational spectrum are directly compared with those predicted by ab initio methods to achieve the conclusive identification of seven different conformers as mentioned in this paper.
Journal ArticleDOI
Revealing the multiple structures of serine.
TL;DR: From the postexpansion abundances, the conformational stability trend is derived, which is controlled by the subtle network of intramolecular hydrogen bonds formed between the polar groups in the amino acid backbone and the hydroxy side chain.
Journal ArticleDOI
Conformations of γ‐Aminobutyric Acid (GABA): The Role of the n→π* Interaction
TL;DR: The present work observed and characterized nine conformers of GABA using Fourier transform microwave spectroscopy in supersonic jets combined with laser ablation and confirmed the conformational richness of GABA.
References
More filters
Journal ArticleDOI
Intermolecular interactions from a natural bond orbital, donor-acceptor viewpoint
Journal ArticleDOI
Amino acids from ultraviolet irradiation of interstellar ice analogues.
G. M. Muñoz Caro,Uwe J. Meierhenrich,W. A. Schutte,Bernard Barbier,A. Arcones Segovia,H. Rosenbauer,Wolfram Thiemann,A. Brack,J.M. Greenberg +8 more
TL;DR: The results demonstrate that the spontaneous generation of amino acids in the interstellar medium is possible, supporting the suggestion that prebiotic molecules could have been delivered to the early Earth by cometary dust, meteorites or interplanetary dust particles.
Journal ArticleDOI
Racemic amino acids from the ultraviolet photolysis of interstellar ice analogues
Max P. Bernstein,Max P. Bernstein,Jason P. Dworkin,Jason P. Dworkin,Scott A. Sandford,George Cooper,Louis J. Allamandola +6 more
TL;DR: A laboratory demonstration that glycine, alanine and serine naturally form from ultraviolet photolysis of the analogues of icy interstellar grains is reported, suggesting that at least some meteoritic amino acids are the result of interstellar photochemistry, rather than formation in liquid water on an early Solar System body.
Journal ArticleDOI
Geometrical reaction coordinates. II. Nucleophilic addition to a carbonyl group
Journal ArticleDOI
Stereochemistry of reaction paths at carbonyl centres
TL;DR: In this article, the reaction paths found by different methods for different nucleophiles show some striking similarities that appear to be characteristic for the reaction type, and the results of recent experimental and theoretical studies of nucleophilic addition to carbonyl groups are described.