Organic Crystal Growth: Directly from Amorphous Solid Powder to Single Crystals.

Preparation of organic crystals mainly depends on solution-deposition, sublimation, and melt-deposition techniques. Solid-state growth methods are generally not suitable for organic crystal growth due to the unprocurable mass transfer. Herein, we report two pyridine-substituted fluorenone compounds with extraordinary crystal-growth capacity, and these compounds can directly and quickly form single crystals from their amorphous solid powder by heating under antisolvent-assistance conditions. The novel experimental phenomenon and crystal growth mechanism were investigated in depth. The results indicate that multiple intermolecular hydrogen-bonding sites and planar aromatic structure (prone to π-π interactions) of these molecules dominate the mass transfer during crystal growth by providing enough energy. This discovery enhances our knowledge of solid-state methods for single-crystal growth.