Phase dependent luminescent property of N,N-di(n-octyl)quinacridone crystals

Abstract A polymorph A and a pseudopolymorph B of N,N-di(n-octyl)quinacridone (DOQA) have been prepared by altering the crystal growth conditions and their molecular structures have been identified by single-crystal X-ray diffraction. Both polymorphs show similar characteristics of molecular structures and their molecular arrangements are characterized by the intermolecular π…π interactions and C H…O hydrogen interactions. Due to the presence of methanol molecules in the form B, it is found that in crystalline polymorphs A and B the distance and the degree of overlap of π-electron are remarkably different. Simultaneously, molecules of two forms show different hydrogen bonding patterns. The different molecular packing structures result in significantly different morphologies, namely block shape for A whereas needle shape for B, and solid-state luminescent properties of two forms. From the X-ray single-crystal analysis, the obvious different molecular packing structures of two forms, due to the presence of methanol molecules in the form B, urge us to investigate the phase-dependent emission properties of DOQA in microstructures. DOQA can be employed as building blocks to fabricate luminescent microscale wires by controlling the ratio of methanol solvent.