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 similar to 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.

Automated summary

By using a polyaromatic capsule, azobenzene and stilbene derivatives can be quantitatively encapsulated with 100% cis-selectivity and their isomerization can be suppressed. Similarly, C,N-diphenyl imine derivatives can be encapsulated in their otherwise unstable cis-form and their hydrolysis can be inhibited. Supramolecular manipulation allows for significant alteration of the properties of cis-trans isomers.