Polarized Luminescence of the Microcrystals of Two Pyridine-Function-alized Small Molecules and Their Ionic Co-assemblies

Abstract The rational manipulation of polarized luminescence in crystalline-state organic semiconductors is of paramount importance for on-chip photonic integration, yet it remains constrained by the difficulty of programmatically controlling molecular transition dipole orientations within solid-state architectures. Herein, we demonstrate a supramolecular co-crystallization strategy that enables concurrent spectral red-shift and polarization-state engineering in pyridine-functionalized molecular microcrystals. By introducing a sulfonic acid co-former, we successfully construct binary cocrystals with distinct morphological and packing topologies compared to their single-component counterparts. Single-crystal X-ray diffraction reveals that directional N−H···O−S hydrogen-bonding motifs act as the structural linchpin, enforcing a strictly linear packing arrangement that dictates the anisotropic optical response. Notably, beyond the anticipated bathochromic shift in emission maxima, the co-crystallization induces a fundamental transformation in the polarization characteristicsswitching the emitted light from linear to elliptical polarizationas a direct consequence of the altered molecular transition dipole coupling within the hydrogen-bonded framework. This work establishes a structure−property correlation linking supramolecular connectivity to macroscopic photonic behavior, offering a versatile and predictive design rule for the fabrication of next-generation multifunctional polarized-light-emitting microdevices.