Conformational Landscape of Supersonically Expanded 1‐(Fluorophenyl)ethanols and Their Monohydrated Clusters

Abstract

The effects of the presence of the ring fluorine atom on the conformational landscape of supersonically expanded isomeric 1-(fluorophenyl)ethanols and their monohydrated clusters are investigated by resonant two-photon ionization (R2PI) spectroscopy, coupled with time-of-flight (TOF) mass spectrometry. In contrast to the very simple spectrum of 1-phenylethanol, the lack of structural symmetry of the aromatic rings of isomeric 1-(fluorophenyl)ethanols generates more complicated spectra, characterized by several low-frequency progressions of bands. Their interpretation is based on the strict correspondence with theoretical predictions at the D-B3LYP/6-31G** level of theory. Monohydration of the 1-(fluorophenyl)ethanol isomers favours exclusive formation of the corresponding conformers, characterized by the O-H...O(w)-H...pi intracomplex interaction and whose excitation spectrum exhibits features attributed to the C(1)-C(alpha) torsion plus intermolecular water torsion.

Chlorine Para-Substitution of 1-Phenylethanol: Resonant Photoionization Spectroscopy and Quantum Chemical Calculations of Hydrated and Diastereomeric Complexes

“…This result is in agreement with that found in the monohydrated p-FE S complex, 19 for which a red shift was obtained.…”

“…As for the analogous structures of p-FE S and E R , 19,35 structures A and C are stabilized by an intramolecular OH···π hydrogen bond, 36,37 whereas in B the hydroxyl hydrogen points to the opposite side to the phenyl ring. A C 2 H···O additional hydrogen bond is established in all the three structures.…”

Chiral recognition between 1-(4-fluorophenyl)ethanol and 2-butanol: higher binding energy of homochiral complexes in the gas phase

“…1). 16 The spectrum of the homochiral [FE S ÁB S ] complex is characterized by an intense band at 36 853 cm À1 , accompanied by a low frequency mode progression with a spacing of 17 cm À1 (bands labeled 1-7 in Fig. 1a and 5a).…”

“…13 An important aspect of R2PI studies concerns the measure of the binding energy differences in a few adducts between chiral benzylic alcohol derivatives and chiral secondary alcohols, which is in the range of 250-400 cm À1 with the homochiral complexes always more stable than the corresponding heterochiral complexes. 13,14 Recently we have applied this methodology to fluorinated analogues 15,16 of chiral aromatic alcohols, with the aim of determining the effect of fluorine substitution on the structure and reactivity properties of their complexes and to verify the role of the fluorine substitution on the chiral recognition process. Organofluorine compounds, although rare in nature, are increasingly applied in metabolic studies, in positron emission tomography, as antitumor agents, and as probes in studying enzyme activity, reaction mechanisms, and biomolecular binding.…”

Free jet rotational spectrum of the most stable conformer of 1-(2-fluorophenyl)-1-ethanol

“…doi:10.1016/j.jms.2010.01.007 ionization spectroscopy [22]. Since the spectral lines were assigned to the various conformers based on the D-B3LYP/6-31G ** calculations, we believe to be useful, for an unequivocal experimental conformational assignment, the investigation of their pure rotational spectra.…”