Multiple cation-π interactions between the trimethylammonium moiety and the aromatic rings within a molecular complex formed between 3-phenylpropionic acid choline ester and resorcin[4]arene

X-ray analysis of the molecular complex formed between 3-phenylpropionic acid choline ester (1) and tetraethylresorcin[4]-arene (2) has shown that the choline ester 1 is captured by the bowl-shaped 2 through multiple cation-π interactions between the quaternary trimethylammonium group of 1 and the aromatic rings of 2 and that 1 itself forms a folded structure to make close contacts between its trimethylammonium moiety and the phenyl ring through cation-π interactions.