Abstract
Pyridine[4]arenes have previously been considered as anion binding hosts due to the electron-poor nature of the pyridine ring. Herein, we demonstrate the encapsulation of Me4N+ cations inside a dimeric hydrogen-bonded pyridine[4]arene capsule, which contradicts with earlier assumptions. The complexation of a cationic guest inside the pyridine[4]arene dimer has been detected and studied by multiple gas-phase techniques, ESI-QTOF-MS, IRMPD, and DT-IMMS experiments, as well as DFT calculations. The comparison of classical resorcinarenes with pyridinearenes by MS and NMR experiments reveals clear differences in their host–guest chemistry and implies that cation encapsulation in pyridine[4]arene is an anion-driven process.
Highlights
Resorcinarenes and their derivatives are known for the molecular recognition properties of their self-assembled dimeric and hexameric capsules, which can encapsulate cationic and neutral guests [1,2,3]
With the help of ion mobility mass spectrometry (IM-MS), we showed that pyridine[4]arenes favor encapsulation of neutral molecules over anionic species and anions are complexed in an exo-position between the lower-rim alkyl chains [11]
As the cavity sizes of both pyridinearene and resorcinarene dimers are comparable, alkylammonium cations were chosen as the guests for complexation studies with electrospray ionization (ESI)-Q-TOF mass spectrometry
Summary
Resorcinarenes and their derivatives are known for the molecular recognition properties of their self-assembled dimeric and hexameric capsules, which can encapsulate cationic and neutral guests [1,2,3]. The complexation of a cationic guest inside the pyridine[4]arene dimer has been detected and studied by multiple gas-phase techniques, ESI-QTOF-MS, IRMPD, and DT-IMMS experiments, as well as DFT calculations.
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