Supramolecular-gel Gelators for Recrystallization and Polymorph Control

The compounds 1 and 2, which are composed of two nitrophenylurea moieties via a carbon tether moiety, are utilized as supramolecular gelators. When small amount of gelator is dissolved in organic solvents, robust gels are afforded while simultaneously binding with dissolved compounds which have applications in pharmaceutical chemistry. This gelation is applicable to various nonpolar solvents like toluene and, as well as polar solvents such as alcohols. Furthermore, Steed et al. have reported that they can control the polymorph of compound 3 through these gels. Once 3 has been recrystallized from a toluene gel, the meta-stable red crystalline form is obtained.