Crystal structure and third-order nonlinear optical properties of supramolecular cocrystals of 18-crown-6 with 5-aminoisophthalic acid

Self-assembled supramolecular cocrystals of 18-crown-6.2(5-aminoisophthalic acid) have been synthesized from 18-crown-6 (18C6) and 5-aminoisophthalic acid (5AIPA) (stoichiometric ratio 1:2). The single-crystal X-ray analysis revealed the crystal structure, indicating a monoclinic system with the centrosymmetric space group C2/m. The assembly of the supramolecular structure primarily relies on N–H···O and O–H···O interactions. Characteristic functional groups were identified using FT-IR and micro-Raman spectral analyses. Additionally, the diffuse reflectance spectrum estimated a direct bandgap energy of 2.84 eV. The cocrystal exhibited fluorescent emission in the solid state at room temperature as observed in photoluminescence studies. Analysis utilizing Hirshfeld surface and fingerprint plots unveiled close contacts resulting from robust interactions in the crystal packing. The third-order nonlinear optical properties of the crystal grown were determined using a single-beam Z-scan technique.