A Tb-MOF anion, porous coordination framework constructed with oxalate ligand: Crystal structure, adsorption properties, and luminescence sensing

Abstract

The reaction of Tb(NO)3·6H2O and potassium oxalate (ox) yielded the coordination framework, [CH3NH2CH3][Tb(ox)2(H2O)]·3H2O (Tb-MOF). It shows a 3D anionic framework, which featured one-dimensional (1D) channels (about 13.06 × 13.06 Å2) along the a-, b-, and c-axes, which resulted in a high surface area, as measured by Brunauer–Emmett–Teller (BET) surface area, of 37.585 m2/g. The N2/CO2 adsorption for the complex was measured at 77 K. The solid-state Tb-MOF exhibited strong green luminescence assigned to the 5D4→7FJ (J = 6–3) transition in the visible region, which can be observed by the naked eye under irradiation with 365 nm near-UV light. When immersing Tb-MOF in aqueous solutions, the Tb(III) characteristic luminescence was also maintained and its emission with maximum intensity was reached over the pH range 4–11. The complex was an attractive luminescence material, and its luminescence sensing properties were discussed in detail. Fluorescent measurement results show that the complex had high sensitivity detection for imidacloprid and thiamethoxam in water solutions with low detection limits of 1.3 × 10−5 M−1 and 7.3 × 10−6 M−1, respectively. Also, Tb-MOF has been explored for the adsorption and release of ibuprofen.