Contiguous layer based metal–organic framework with conjugated π-electron ligand for high iodine capture

Abstract

Herein, a novel 3-dimensional (3D) Cu(II) metal–organic framework (MOF), [Cu₃(μ₂-O)₂(p-tr₂Ph)₂(HCOO)][NO₃]·3DMF·3H₂O (compound 1), which is constructed by directly interlocking regionalized hollow two-dimensional (2D) layers, has been conceived and solvothermally synthesized. Such a distinctive regionalized pore system effectively maintains the uniformity of the pore structure, isolates the counterions and bridging ligands in the partition layer, and endows compound 1 with high porosity. In consequence, compound 1 exhibits excellent adsorption ability of iodine in cyclohexane. The removal efficiency in cyclohexane solution (0.01 mol L⁻¹) can reach up to 80% in 8 min, and the absorption ability towards iodine can reach about 1.15 g g⁻¹. Moreover, iodine can also be controllably released in ethanol. The release rate was up to 4 × 10⁻⁵ mol L⁻¹ min⁻¹. Furthermore, compound 1 also showed prominent recyclability due to the high stability, and the maximum sorption amount could be retained after 3 cycles. This study paves a new way towards opening up MOFs’ potential application in capturing radioactive iodine to protect the environment.