Séminaire du laboratoire PhLAM par Alberto LESARRI

Le séminaire sera animé par Alberto LESARRI, Professeur à l'Université de Valladolid (Espagne), et aura pour thématique "Exploring Molecular Dimerization in the Gas Phase Using Broadband Rotational Spectroscopy:  π -Stacking vs Hydrogen Bond ". 

Résumé : 

This talk will explore molecular dimerization in the gas phase using jet-cooled chirped-pulse rotational spectroscopy. The molecular targets will include mono and biarenes functionalized with a thiol or an alcohol group. This study illustrates the molecular factors balancing π-stacking and hydrogen bonding, typically showing a negative correlation. The smaller monoarene dimers like (thiophenol)₂, (phenol)₂ and (thiophenol···phenol) display radically different behavior depending on the strength of the hydrogen bond. Specifically, the thiophenol dimer exhibits a weak a S-H···S hydrogen bond and π-stacking, contrasting with the hinged structure of the O-H···O hydrogen bond in (phenol)₂ or the partially stacking structure of thiophenol···phenol, stabilized by an O-H···S hydrogen bond. The thiophenol dimer is also notorious because of the presence of internal dynamics and dimerization isomerism. Enlarging the side chain, as in (benzyl mercaptan)₂ or (phenethyl mercaptan)₂, destroys π-stacking. Conversely, π-stacking is reinforced in the biarenes by the presence of a second aromatic ring. Two isomers were observed for the stacking dimer of (2-naphthalenethiol)₂, which lacks a hydrogen bond. However, the heterodimers of (1-naphthalenethiol···1-naphthol) or (2-naphthalenethiol···2-naphthol) display again a partially stacking structure caused by an O-H···S hydrogen bond.

Le résumé est disponible ici.