Simultaneous endo and exo Complex Formation of Pyridine[4]arene Dimers with Neutral and Anionic Guests

Complex formation between hexafluorophosphate (PF6−) and tetraisobutyl-octahydroxypyridine[4]arene (1) has been thoroughly studied in gas phase (ESI-QTOF-MS, IM-MS, DFT calculations), solid state (X-ray crystallography) and in chloroform solution (1H, 19F and DOSY NMR). In all states of matter, simultaneous endo-complexation of solvent molecules and exo-complexation of PF6− anion within pyridine[4]arene dimer was observed. While similar ternary complex formation is often observed in solid state, this is a unique example of such behaviour in the gas phase that has never been observed so far.