Host‐Guest Chemistry in a Capillary Applied to the Facilitation of the Crystalline Sponge Method

Capillary is a handy tool for transferring, mixing, and storing small volumes of liquid. Here, we show that the stepwise dipping of host and guest solutions into a capillary allows efficient preparation, crystallization, and X-ray analysis of various host-guest complexes. The crystals formed in capillaries are comparable in quality to those grown in regular flasks and subjected to X-ray analysis without being removed from the capillary. We further apply the capillary technique to the crystalline sponge method, a practical domain of host-guest chemistry, successfully overcoming several technical issues.