Under these abundant intermolecular interactions, o-ClTPA adopts a compact packing mode which is conducive to suppressing nonradiative decays. In contrast, fewer intermolecular interactions exist in isomers m-ClTPA and p-ClTPA. Consequently, m-ClTPA exhibits a loose packing style due to the existence of a freely rotatable phenyl unit, but a much tighter and ordered molecular arrangement is formed in p-ClTPA due to the symmetric molecular configuration. In addition, the melting pointing of p-ClTPA is much higher than m-ClTPA (Figure ), which also indicates the stronger intermolecular interactions of p-ClTPA in crystals.