First-Principles Study of Square Chalcogen Bond Interactions and its Adsorption Behavior on Silver Surface

Research on 2Ch⋯2N (Ch = S, Se, Te) square chalcogen interaction has attracted extensive attention in recent years. By search of the Crystal Structure Database (CSD), square chalcogen structures with 2Ch⋯2N interactions were widely found. Herein, dimers of 2,1,3-benzothiadiazole (C6N2H4S), 2,1,3-benzoselenadiazole (C6N2H4Se) and 2,1,3-benzotelluradiazole (C6N2H4Te) from CSD were chosen to construct a square chalcogen bond model. The square chalcogen bond and their adsorption behavior on Ag(110) surfaces have been systematically studied using first principles. Furthermore, partially fluoro-substituted C6N2H3FCh (Ch = S, Se, Te) complexes were also considered for comparison. The results show that in the C6N2H4Ch (Ch = S, Se, Te) dimer, the strength of the 2Ch⋯2N square chalcogen bond is in the order of S < Se < Te. In addition, the strength of the 2Ch⋯2N square chalcogen bond is also enhanced by F atom replacement in partially fluoro-substituted C6N2H3FCh (Ch = S, Se, Te) complexes. The self-assembly behavior of dimer complexes on silver surfaces is guided by van der Waals interactions. This work provides theoretical guidance for the application of 2Ch⋯2N square chalcogen bonds in supramolecular construction and materials science.