Optical materials represent a class of exotic materials
in optics,
lenses, lasers, optic fiber communication, and optical storage devices, etc. Organic optical materials are excellent alternatives
to conventional inorganic optical materials because of their flexibility,
low costs, environmentally friendly nature, etc. Here,
we report color trimorphism (three polymorphic forms: orange, light-orange,
and yellow, abbreviated as OLY) in an organic chromophore via systematic physicochemical characterizations. We focused
on a N,N-dimethyl bromo substituted
thienyl chalconea push–pull chromophore. We performed
physicochemical characterizations using UV–vis, solid-state
photoluminescence, powder and single-crystal X-ray diffraction, differential
scanning calorimetry, thermogravimetric analysis, and hot-stage microscopy
to highlight the similarities and differences in the OLY forms of
the title compound. We also calculated the lattice and interaction
energies and compared them to understand the energetic stabilities
of the polymorphs. Further, based on electron densities calculated
for the selected dimers extracted from the crystal structure, we quantified
the intermolecular interactions and highlighted the differences in
electron density distributions across the three polymorphs. The detailed
analysis of the crystal structures suggests that this is a case of
packing color polymorphism. The colors of these polymorphs correlate
well with the results obtained from the spectroscopic and computational
studies.