Diphenylamine substituted 5,6,12,13-tetraazaperopyrene based polymorphic microcrystals versatile in multi-directional isotropic and anisotropic photon transport

Abstract

Geometrically well-defined microcrystals with polymorphic tailorability are in high demand for multi-directional photon flow at the microscale. Herein, diphenylamine (DPA) substituted 5,6,12,13-tetraazaperopyrene c-TAPP-DPA is synthesized and explored as a versatile fluorophore to fabricate polymorphic microcrystals for photonic applications. The flexibly twisted and electron rich DPA groups are verified as a crucial structure element to tune the intermolecular interactions and packing modes of c-TAPP-DPA, resulting in three kinds of crystals, including microrods, and rhomboid and hexagonal microplates. These microcrystals display geometry-dependent fluorescence properties and 1D or 2D waveguide properties with low optical loss. Impressively, the micro-rhomboids show a unique 2D asymmetric waveguide character. Our work enriches the diversity of polymorphic microcrystals, and sheds more light on the structure–property relationship of organic crystals for multi-directional optical waveguide applications.