Takudrei

Hydrogen/Deuterium Exchange Reactions in the Gas-Phase

Gas-phase hydrogen/deuterium exchange reactions on hydrogen-bonded ions yield quite detailed information on mechanistic and structural aspects of isolated supramolecules. It has been utilized to provide evidence for the intramolecular mobility of crown ethers within oligolysin/[18]crown-6 and POPAM dendrimer/[18]crown-6 complexes and thus highlights the surprisingly pronounced dynamics within such complexes.

Furthermore, a concerted H/D-exchange mechanism operating in dimeric resorcinarene capsules could be detected which resembles a one-dimensional variant of the well-known Grotthus mechanism for proton transport in water.

These H/D-exhcange experiments finally resulted in the observation that large crowns (e.g. [24]crown-8 and beyond) catalytically drive the ammonia elimination reaction of primary amines by simultaneously enhancing the leaving group capability of the ammonia molecule and offering a base for the proton at C(2).

 

Mercator projection of the hydrogen bonding seam of a dimeric resorcinarene capsule and concerted H/D-exchange reaction with methanol-OD

 

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