Synthesis of a Copper 1,3,5-Triamino-2,4,6-benzenetriol Metal–Organic Framework

We report the synthesis and characterization of a two-dimensional (2D) MX₂Y₂-type (M = metal, X, Y = N, S, O, and X ≠ Y) copper 1,3,5-triamino-2,4,6-benzenetriol metal-organic framework (Cu₃(TABTO)₂-MOF). The role of oxygen in the synthesis of this MOF was investigated. Copper metal is formed along with the MOF when the synthesis is done in argon as suggested by XRD. When the reaction was exposed to air with vigorous stirring, copper metal was not observed by XRD. However, if there is no stirring, then copper metal is formed, and we learned that this is because oxygen was not allowed to enter the solvent due to the formation of a MOF film at the air/water interface. For the sample synthesized in argon (Cu₃(TABTO)₂-Ar), an insulating Cu₃(TABTO)₂-Ar pellet (σ < 10^-10 S cm^-1) became a metallic conductor with an electrical conductivity of 0.78 S cm^-1 at 300 K after exposure to iodine vapor. This work provides further insights into the role of oxygen in the synthesis of redox-active ligand-based MOFs, expands the family of 2D redox-active ligand-based electrically conductive MOFs, and offers more opportunities in sensing, photocatalytic, electronic, and energy-related applications.