Phase-Selective Crystallization of Perylene on Monolayer Templates

The planar aromatic hydrocarbon perylene serves as the core unit in many photoconductive and electronic materials. Perylene crystallizes in two polymorphic forms, α and β, which grow concomitantly from many solvents. Crystallization in the presence of a small library of gold–thiol self-assembled monolayers (SAMs) and functionalized siloxanes identified conditions under which phase pure material can be obtained. Au-biphenylthiol SAM templates nucleated phase pure α-perylene with preferred alignment along the α-(100) plane. Siloxanes with terminal amino functionalities proved to be effective templates for the generation of phase pure β-perylene aligned along β-(100). Phase mixtures grew on most other templates examined. Comparison of the morphologies and nucleation densities of crystals grown under various conditions suggests that the phase selectivity observed on these templates is also sensitive to solvent choice and solute concentration