A mixed valence Tb(III)/Tb(IV) metal-organic framework: Crystal structure, luminescence property and selective detection of naproxen

Chao-Yang Wang, Baoyi Yu, Huifen Fu, Peng Wang, Chong-Chen Wang*

A mixed valence terbium metal-organic framework (MOF), [Tb₂(HCOO)(clhex)·2H₂O)]·2H₂O (BUC-68) was obtained from the reaction of 1,2,3,4,5,6-cyclohexanehexacarboxylic acid (H₆clhex), formic acid, N,N-dimethylformamide  (DMF) and the terbium salt under hydrothermal condition at 140 ℃. The crystallographic analysis revealed that the three-dimensional BUC-68 is composed of two-dimensional [Tb₂(clhex)·2H₂O)] sheets linked by formic ligand. X-ray photoelectron spectra (XPS) analysis revealed that there were terbium (III) and terbium (IV) presented in BUC-68. Thermogravimetric analysis (TGA) indicated that BUC-68 was stable up to 350 ℃. Photoluminescent measurement showed that BUC-68 displays strong luminescence emission, which was arose from efficient ligand to metal energy transfer transitions. Finally, BUC-68 was utilized to conduct selective detect of naproxen (NPX) and some small organic molecules.