Orientational isomerism and binding ability of nonsymmetrical guests encapsulated in a self-assembling heterodimeric capsule

The ability of a guest to induce the assembly of tetracarboxylcavitand 1 and tetra(3-pyridyl)-cavitand 2 into a heterodimeric capsule 1.2, and the orientational isomerism of nonsymmetrical p-disubstituted-benzene guests encapsulated in 1.2, are described. For example, the ability of a guest to induce the assembly of guest subset of(1.2) increases in the order p-iodoaniline <= p-chloroanisole < p-bro-moanisole < N-methyl-p-iodoaniline < p-iodoanisole. For these five guests encapsulated in 1.2, the halogen atoms are specifically oriented with respect to the cavity of the 2 unit. By contrast, the orientational isomeric selectivities of p-chloroiodobenzene, p-bromoiodobenzene, and p-methylanisole encapsulated in 1.2 are quite low, in the range of 1:1.7 to 1:1. The ortho-fluoro derivatives of these three guests, however, are encapsulated in 1.2 with a highly selective orientation, in which the substituent next to the fluorine atom greatly prefers the cavity of the 2 unit to that of the 1 unit.