Additive-Free Morphology Control of Organic Polyhedral Molecular Crystals by the Antisolvent Molecular Geometry: From Rod, Disk, to Cube

Abstract

The role of antisolvent molecular geometry on the determination of the final molecular crystals morphology formed by the reverse antisolvent crystallization (r-ASC) process has been unveiled. Herein, we newly report that the rod-, disk-, and cube-shaped tetra(4-aminophenyl)porphyrin molecular crystals were selectively obtained by employing o-, m-, and p-xylene as an antisolvent during r-ASC process with ethanol employed as a good solvent. The X-ray diffraction results of the crystals provide a clear indication about the correlation between the solute–solvent interactions and the resulting crystal morphologies. The results show that the geometry of xylene has a pivotal effect on the crystal growth direction and morphologies, especially for polyhedrons. This finding would provide opportunities not only for realization of quite rare organic polyhedral crystals but also for in-depth studies about the fundamental crystallization process.