A new family of Ln-BTC-AC-FM framework intelligent materials: Precise synthesis, structure and characterization for fluorescence detecting of UO22+ and adsorbing dyes

Abstract

The unique fluorescence properties of rare earth ions and subtle interactions with organic ligands make the target lanthanide metal-organic frameworks show potential development prospects in many fields. Based on this situation, a series of new lanthanide metal-organic frameworks Ln-BTC-AC-FM: (CH3)2NH2[Ln2(BTC)(AC)3(FM)], (Ln=Pr (1), Ce (2), Nd (3), Eu (4), Sm (5), Gd (6), Tb (7), Ho (8), Er (9) and Yb (10), H3BTC=1,3,5-benzenetricarboxylic acid) were synthesized through the reaction of triangular polycarboxylic acid ligand (H3BTC) and rare earth nitrate Ln(NO3)3·6H2O with mixed formic acid (FM) and glacial acetic acid (AC) system. Due to this new type of Ln-BTC-AC-FM MOFs have unique and excellent fluorescence properties, we selected (CH3)2NH2[Eu2(BTC)(AC)3(FM)] (4) to explore its detection performance for UO22+ in aqueous solution. The study found that 4 is a high-efficiency fluorescent probe, which has a good quenching effect on uranium solution, and the quenching rate can reach 98.01%. At the same time, 4 has a good fluorescent response to UO22+, with a higher KSV value of 8.56 × 103 M−1 and a lower detection limit of 4.12 μM. In addition, we also studied the adsorption properties of this series of Ln-BTC-AC-FM MOFs for dyes because of their novel three-dimensional microporous structures. The results showed that 4 has a good adsorption effect on Coomassie Brilliant Blue (CBB) and Eosin. Moreover, it was found that the dye adsorption process was proved to be a suitable pseudo-second-order kinetic model.