Optical Waveguide and Photoluminescent Polarization in Organic Cocrystal Polymorphs

Organic
cocrystals whose unique polymorphic feature can provide
a feasible way to investigate and understand the relationship between
luminescence properties and aggregate structures have attracted increasing
attention in the area of organic optoelectronics. Herein, we prepare
polymorphic cocrystals (C1, C2) by using 9,10-bis­((E)-2-(pyridin-3-yl)­vinyl)­anthracene (BP3VA) as chromophore and 1,3,5-trifluoro-2,4,6-triiodobenzene
(FIB) as conformer. Both C1 and C2 stack with segregated stacking
form, but different intermolecular interactions promote the formation
of sheet cocrystals C1 and needle cocrystals C2. C1 exhibits anisotropic
optical waveguide property and photoluminescent polarization, while
C2 only exhibits the quasi-one-dimensional optical waveguide property.
The different optical properties originate from the varieties of molecular
packing modes and directions of the optical transition dipole in the
two polymorphic cocrystals, which can be clarified through the structure
analysis and theoretical calculation. The study can provide a deep
understanding of the structure–property relationship of cocrystals
and benefit the rational design of novel functional materials.