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Titolo:
Conformational preferences of neurotransmitters: Ephedrine and its diastereoisomer, pseudoephedrine
Autore:
Butz, P; Kroemer, RT; Macleod, NA; Simons, JP;
Indirizzi:
Univ Oxford, Phys & Theoret Chem Lab, Oxford OX1 3QZ, England Univ OxfordOxford England OX1 3QZ ret Chem Lab, Oxford OX1 3QZ, England Univ London Queen Mary & Westfield Coll, Dept Chem, London E1 4NS, EnglandUniv London Queen Mary & Westfield Coll London England E1 4NS S, England
Titolo Testata:
JOURNAL OF PHYSICAL CHEMISTRY A
fascicolo: 3, volume: 105, anno: 2001,
pagine: 544 - 551
SICI:
1089-5639(20010125)105:3<544:CPONEA>2.0.ZU;2-1
Fonte:
ISI
Lingua:
ENG
Soggetto:
SINGLY HYDRATED COMPLEX; SEEDED SUPERSONIC JETS; CHIRAL MOLECULES; SPECTROSCOPY; CONFORMERS; DISCRIMINATION; RELAXATION; CLUSTERS; RECEPTOR; ISOMERS;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Citazioni:
27
Recensione:
Indirizzi per estratti:
Indirizzo: Simons, JP Univ Oxford, Phys & Theoret Chem Lab, S Parks Rd, Oxford OX1 3QZ, England Univ Oxford S Parks Rd Oxford England OX1 3QZ OX1 3QZ, England
Citazione:
P. Butz et al., "Conformational preferences of neurotransmitters: Ephedrine and its diastereoisomer, pseudoephedrine", J PHYS CH A, 105(3), 2001, pp. 544-551

Abstract

The conformational preferences of the diastereomeric neurotransmitters (1R2S) ephedrine and (1S2S) pseudoephedrine have been studied in the gas phase, under free jet-expansion conditions, using ultraviolet spectroscopy (bothR2PI and LIF) and infrared ion-dip and hole-burning spectroscopy in combination with ab initio calculation. This has led to the identification and assignment of two conformers in ephedrine and four in pseudoephedrine. Assignments have been made by comparing their experimental infrared and LIF spectra with ab initio vibrational frequencies and ultraviolet rotational band contours. The relative stabilities of the conformers are controlled by a delicate balance between intramolecular hydrogen bonding and dispersive interactions between the methyl groups of the side chain, both with each other and with the aromatic ring. The relative conformational stabilities calculated for ephedrine do not agree with the experimental results; two of its low-lying conformers were detected, but a third, lying at an intermediate energy, was not. The possibility of its collisional relaxation into the global minimum during the supersonic expansion was not supported by the ab initio calculations, which predict a substantial barrier along the minimum energy pathway. It is possible that the combination of a relatively weak transitionmoment and a lack of facile pathways for relaxation from higher lying structures into the "missing" conformer may play a role.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 25/01/21 alle ore 18:28:32