Selective Encapsulation and Unusual Stabilization of cis‐Isomers by a Spherical Polyaromatic Cavity.

To explore new cavity functions, we herein employed cis‐trans stereoisomers with a N=N, C=C, or C=N unit as guest indicators for a polyaromatic capsule. Thanks to the rigid, spherical cavity with a diameter of ∼1 nm, azobenzene and stilbene derivatives are quantitatively encapsulated by the capsule with 100 % cis‐selectivity in water. The isomerization of the cis‐azo compound is suppressed against heat and light in the cavity, due to the confinement effect. Furthermore, C,N‐diphenyl imine derivatives are quantitatively encapsulated by the capsule in water and adopt an otherwise unstable cis‐form. The polyaromatic cavity suppresses the hydrolysis of the imines in water, even at elevated temperature, due to the shielding effect. Accordingly, the properties of the cis‐trans isomers could be largely altered through supramolecular manipulation. [ABSTRACT FROM AUTHOR]