Cu(I) 3,5-Diethyl-1,2,4-Triazolate (MAF-2): From Crystal Engineering to Multifunctional Materials

Among various types of nonporous and porous coordination polymers, and as a subset of metal azolate frameworks (MAFs), Cu(I) 1,2,4-triazolates are unique for their simple three-connected network topologies which can be controlled by their significant steric hindrance effects between the noncoordinative side groups. This perspective article discusses the crystal engineering, structures, and diversified properties of Cu(I) 1,2,4-triazolates, particularly focusing on the porous coordination polymer [Cu(detz)] (MAF-2, Hdetz = 3,5-diethyl-1,2,4-triazole) showing unique/multimode flexibility, high hydrophobicity, bright phosphorescence, and exceptionally high stabilities toward not only guest change but also water and oxygen, which have demonstrated as a good platform for realizing high-performance applications related to gas/vapor confinement, storage, separation, and sensing. The exceptional O2 reactivity and the tunable framework flexibility, pore surface polarity, and gas separation performances of [Cu4(btm)2] (MAF-42, H2btm = bis(5-methyl-1,2,4-triazol-3-yl)methane) are also summarized.