Formation of New Polymorphs of Acridine Using Dicarboxylic Acids as Crystallization Templates in Solution

Two new polymorphic structures of acridine have been prepared using terephthalic and cis,trans-muconic acid as templates in a supersaturated phase to affect the nucleation process and crystal growth of acridine by hydrogen-bonding and π−π interactions. Isothermal evaporation of a solution of acridine in ethanol afforded a single crystal structure consisting of V-shaped arrangements of dimeric acridine π-stacks (acridine II), whereas the template-assisted crystallization approach resulted in the formation of the new polymorphs acridine VI and VII exhibiting less regular packing motifs.