15min:

VANESSA CORTIJO, RAQUEL SÁNCHEZ, M. EUGENIA SANZ, JUAN C. LÓPEZ AND JOSÉ L. ALONSO, Grupo de Espectroscopía Molecular (GEM), Departamento de Química Física y Química Inorgánica, Facultad de Ciencias, Universidad de Valladolid, E-47005 Valladolid, Spain.

The first gas phase rotational spectrum of ephedrine, a synthetic analog of the neurotransmitter adrenaline with similar effects on the cardiovascular system, has been observed using a molecular beam Fourier transform microwave spectrometer. Solid ephedrine (m.p. 36~^\circC) was vaporized by heating it in a reservoir located in pulsed valve. In these conditions the three lowest-energy conformers of ephedrine have been detected. Hyperfine structure due to the presence of a ¹⁴N nucleus (I=1) has been observed for all conformers, allowing the unambiguous assignment of their spectra.

Microwave spectroscopy in supersonic jets has been also applied to the conformational and structural analysis of the p-methoxiphenylethylamine molecule. The rotational spectra of the seven conformers previously observed by Pratt et al . have been unambiguously assigned on the basis of the values of their rotational and nuclear quadrupole coupling constants. The predictions of ab initio calculations have been used as guidelines.