Halogen-bonded co-crystals with AIE-active α-cyanostilbenes

A cooperative co-crystal was obtained from the combination of two different aggregation-induced emitting cyanostilbene units: (Z)-3-(4-(dimethylamino)phenyl)-2-(pyridin-4-yl)acrylonitrile (Py) and (Z)-3-(4-(dimethylamino)phenyl)-2-(4-iodophenyl)acrylonitrile (MI). The co-diffraction data revealed that the co-crystals were bound by N⋯I halogen bonding, with a bond distance of 3.019 Å. Furthermore, photophysical studies of the co-crystals (Py-MI) showed excellent aggregation-induced emission characteristics in aqueous media, in comparison to both individual and chromophoric mixtures. Hirshfeld surface analysis was used to quantify the intermolecular interactions, while DFT was used to analyze the electronic structures and frontier molecular orbital energy gap to support these experimental observations. Additionally, the molecules also showed the formation of two-component stable organogels.