Control of Nucleation of Organic Electrooptic Phenolic Polyene Crystals by Highly Polar Liquid Additive

We report on the possibility to control the spontaneous nucleation of the highly efficient electro-optic phenolic polyene OH1 [2-(3-(4-hydroxystyryl)-5,5-dimethylcyclohex-2-enylidene)malononitrile] crystals by a liquid-type additive. Phosphoric acid is chosen as the additive because it is a liquid and much more polar than the growth solvent, methanol. The width of the metastable zone of the OH1 crystals is significantly decreased in the presence of this additive, and fast spontaneous nucleation is observed. In the presence of phosphoric acid, the growth of bulk crystals with a size of 6 × 6 × 2 mm3 and thin plate-like crystals with a large area of about 15 × 15 mm2 is demonstrated.