Molecular amorphous glasses toward large azomethine crystals with aggregation-induced emission

Fifteen azomethine compounds based on different rigid cores and soft aliphatic tails have been designed and synthesized to generate variable supramolecular architectures with distinct thermotropic, photophysical and electrochemical properties. Ten out of the fifteen imines were grown as single crystals and their molecular structures and supramolecular architectures were determined by single-crystal X-ray diffraction. Thermotropic behavior was monitored by polarized-light microscopy and differential scanning calorimetry. Photophysical properties were studied by UV-vis and photoluminescence spectroscopy and electrochemical properties by cyclic voltammetry. It was demonstrated that all supramolecular architectures were mostly generated via weak pi-pi or van der Waals interactions between the rigid cores, which prompts the synthesis of molecular glasses, further giving rise to large crystals displaying an aggregation-induced emission (AIE) effect. We conclude that there is a close relationship between the molecular structures of the imines and their ability to promote favorable properties for optoelectronic applications.