Concomitant Crystallization of ROY on Patterned Substrates: Using a High Throughput Method to Improve the Chances of Crystallization of Different Polymorphs

Abstract

In this study, we demonstrate how increasing the number of crystallization trials can help crystallize polymorphs which may not be obtained in a fewer number of trials due to statistical reasons. Crystallization experiments were conducted using patterned substrates of self-assembled monolayers (SAMs) with solutions of 5-methyl-2-[(2-nitrophenyl)amino]-3-thiophenecarbonitrile (known as ROY for its red, orange, and yellow crystals) in dimethylsulfoxide (DMSO). The patterned bifunctional surface was immersed and slowly withdrawn from undersaturated solutions. The solution preferentially wetted the metallic islands, and as the solvent evaporated, ROY crystals exclusively nucleated on the lyophilic metallic islands. Raman microscopy was utilized to characterize the crystalline form on each metallic island. In one of the experiments, over 10 000 islands were analyzed, and we calculated the probability of crystallizing a particular polymorph on an island. We were able to crystallize six of the seven stable polym...