Solution-mediated and single-crystal to single-crystal transformations of cucurbit[6]uril host–guest complexes with dopamine

Abstract

Host–guest complexation between cucurbit[6]uril and dopamine results in concomitant crystallization of two morphologically distinct supramolecular isomers. Form I appears as prismatic crystals and crystallizes in the P2₁2₁2₁ space group. Form II appears as needles and crystallizes in the R space group. Form I is unstable in solution and spontaneously converts into form II. Additionally, form II undergoes single-crystal to single-crystal dehydration at room temperature mediated by an alteration of the host–guest hydrogen bonding pattern and collective reorganization of dopamine guest molecules.