Ultrasensitive Fe3+ luminescence sensing and supercapacitor performances of a triphenylamine-based TbIII-MOF

The reasonable selection of functional ligands and active metal centers is a priority to fabricate multifunctional metal-organic framework (MOF) materials. Herein, a 3D bifunctional TbIII-MOF, [Tb(TCBPA)∙DMF]n (1) (H3TCBPA ​= ​tris(4′-carboxybiphenyl)amine), is constructed by photoelectricity active triarylamine chromophore and Tb(III) to show excellent photochemical sensing and supercapacitor performances. In 1, the TCBPA3− linkers bridge Tb(III) nodes in a highly torsional fashion to form a non-interpenetrating structure containing 1D rhombic channels with an effective window size of 10.6 ​× ​11.4 ​Å2. The strong green emission and multiple nitrogen/oxygen active sites make 1 work as a reusable heterogeneous fluorescent sensor for ultrasensitive detection of Fe3+ ion with a low detection limit of 3.56 ​ppb. Electrochemical experiments show that the TbIII-MOF exhibits a high specific capacitance of 346 ​F ​g−1 ​at 1 ​A ​g−1 and a remarkable capacitance retention of 93% after 2000 cycles, suggesting outstanding long-term cycling stability and reversibility. Additionally, the possible Fe3+ sensing mechanism was also investigated systematically.