Experimental and simulation investigation of polymorphic phase transformation of N-(2-hydroxy-4-chlorobenzylidene)-4-chlor-oaniline

The polymorphic transition behavior of two forms of N-(4'-chlorosalicylidene)-4-chloroaniline, yellow form (4CC-y) and orange form (4CC-o), in solution-state and solid-state were investigated, respectively. 4CC-y can transform irreversibly to 4CC-o gradually up on heating in solid-state and its transition schema was depicted from packing styles. During recrystallization in solution, 4CC was prefer to crystallize in yellow form. Subsequently, the yellow form transformed to orange form with different speed depending on the solvents. Furthermore, the molecular conformation were analyzed with Materials Studio. Molecular conformational energy contour map with different torsion angles (namely T-1 and T-2) was prepared. The conformer and crystal parking in 4CC-y was demonstrated with lower energy, which elaborate the priority in solution crystallization. (C) 2021 Published by Elsevier B.V.

Automated summary

The polymorphic transition behavior of two forms of N-(4'-chlorosalicylidene)-4-chloroaniline in solution-state and solid-state was investigated in this study. It was found that the two forms exhibited different transition patterns during heating and recrystallization, as well as different crystallization tendencies and speeds in solution. Molecular conformation analysis revealed lower energy conformers and crystal parking in one form, indicating a priority in solution crystallization.