Probing the CH⋅⋅⋅π Weak Hydrogen Bond in Anesthetic Binding: The Sevoflurane–Benzene Cluster

Abstract

Cooperativity between weak hydrogen bonds can be revealed in molecular clusters isolated in the gas phase. Here we examine the structure, internal dynamics, and origin of the weak intermolecular forces between sevoflurane and a benzene molecule, using multi-isotopic broadband rotational spectra. This heterodimer is held together by a primary C-H⋅⋅⋅π hydrogen bond, assisted by multiple weak C-H⋅⋅⋅F interactions. The multiple nonbonding forces hinder the internal rotation of benzene around the isopropyl C-H bond in sevoflurane, producing detectable quantum tunneling effects in the rotational spectrum.

Structural Distortion of the Epoxy Groups in Norbornanes: A Rotational Study of exo‐2,3‐Epoxynorbornane

“…[21,[28][29][30][31] As ingle conformer has been predicted for exo-2,3-epoxynorbornane, as expected from the steric constraints present in the bridged bicyclem otif. This conformer was optimized with the Møller-Plesset perturbation (MP2) and density functional theory (B3LYP and M06-2X functionals).…”

High‐Resolution Spectroscopy of the Chiral Metal Complex [CpRe(CH3)(CO)(NO)]: A Potential Candidate for Probing Parity Violation

“…High-resolution rotational spectroscopy is a powerful way to precisely determine the structures of polar molecules in the gas phase, as for example recently shown for strawberry aldehyde and the sevoflurane-benzene complex. [25,26] The position of each individual atom with respect to the molecules center of mass and thus its structure can be determined by isotopic substitution. In the present study, we cannot directly extract detailed structural parameters from our experimental data since we did not observe other isotopologues besides the ones of rhenium and in particular no 13 C isotopologues, but we can compare the experimental molecular parameters with those from quantum chemical structure calculations.…”

High‐Resolution Rotational Spectroscopy Study of the Smallest Sugar Dimer: Interplay of Hydrogen Bonds in the Glycolaldehyde Dimer

“…[20] Structural information, also for molecular clusters,c an be obtained because the rotational constants obtained from rotational spectra are directly related to the moments of inertia of the molecules.Molecules as heavy as 325 gmol À1 in the case of CpRe(CH 3 )(CO)(NO) have been addressed with CP-FTMW spectroscopy. [21] Quantitative molecular structures can be experimentally determined from an analysis of the rotational spectra of molecular isotopologues.T he changes in the moments of inertia of the isotopically substituted species allow for the building up of the substitution structure atom-by-atom using Kraitchmans equations [22] and/or least-squares fits [23,24] of internal coordinates,f or example,a si th as been recently exemplified for molecular complexes,s uch as the sevoflurane-benzene [25] and the camphor-(H 2 O) 1-3 complexes. [26] In the present study,t he high sensitivity of the technique allowed us to record the 13 C and 18 Oisotopologues of the glycolaldehyde dimer in natural abundance.T he additional rotational constants were then used to determine its heavy-atom backbone structure.Quantum-chemical calculations were used to support the spectroscopic assignment.…”