Guest-encapsulation behavior in a self-assembled heterodimeric capsule

Abstract Tetra(4-pyridyl)-cavitand 1 and tetrakis(4-hydroxyphenyl)-cavitand 2 self-assemble into a heterodimeric capsule 1 · 2 via four PhOH⋯pyridyl hydrogen bonds in CDCl 3 , wherein one molecule of 1,4-disubstituted-benzene as a guest is encapsulated to form a ternary complex, guest@( 1 · 2 ). The X-ray crystallographic analysis of (methyl p -ethoxybenzoate)@( 1 · 2 ) confirmed that the methyl ester and ethoxy groups of the encapsulated guest are oriented to the cavity ends of the 1 and 2 units, respectively. The scope and limitation of guest encapsulation in 1 · 2 , including guest-binding selectivity and orientational isomeric selectivity, are described from the viewpoint of size complementarity and CH–π, CH–halogen, and halogen–π interactions between guest and the cavity of 1 · 2 .