6-connected metal-organic frameworks based on triscarboxylate as a 3-connected organic node and a linear trinuclear Co _3(COO) _6 secondary building unit as a 6-connected node

摘要

The solvothermal reactions of cobalt(II) chloride hexahydrate and 1,3,5-benzenetribenzoic acid (H _3BTB) in anhydrous N,N′-dimethylacetamide (DMA) at two different reaction temperatures and reactant concentrations led to two 3,6-connected metal-organic frameworks (MOFs) with different net topologies based on the ligand as a C _3 symmetric 3-connected organic node and the linear trinuclear cobalt carboxylate cluster, Co _3(COO) _6, as a 6-connected secondary building unit (SBU). MOF [Co _3(BTB) _2(DMA) _4], 1, with a linear trinuclear cobalt carboxylate cluster, Co _3(COO) _6, and with an inversion point symmetry with compressed trigonal antiprismatic 6-connectivity, is a two-dimensional (2-D) layered structure of a 3,6-connected kgd net topology. However, the same linear trinuclear cobalt carboxylate cluster, Co _3(COO) _6, with a 2-fold point symmetry with compressed trigonal prismatic 6-connectivity leads to the three-dimensional (3-D) network of 2, with an unprecedented 3,6-connected net topology with the point symbol (4 ~3) _2(4 ~312 ~(12)). The 2-D layered framework, 1, shows a significant sorption hysteresis for adsorbates with relatively strong interactions with the framework, such as N _2 and CO _2.