Supersonic beam investigations of indole and indole–halomethane complexes: intermolecular interactions

Abstract

We report the findings of a supersonic beam investigation of the 1:1 gas phase complexes of indole with various halomethanes. The unique environment of the supersonic jet provides a method by which the pairwise intermolecular interactions of these complexes can be studied without the complications of condensed media effects. The behavior of argon and methane van der Waals molecules is described first in order to provide examples of simple dispersive interactions. These are then contrasted with complexing species such as CF4 and CCl4 where repulsive interactions offset the stabilization due to dispersive and dipole – induced dipole forces. Finally, we show that the interaction between the probe molecule and CHCl3 and CH2Cl2 is apparently hydrogen bonding with the indole π electronic system. The implications of these intermolecular interactions on the area of general anesthesia are discussed in terms of a picture in which both the hydrophobic and polar portions of cell membrane may be reversibly affected.