posted on 2023-12-10, 18:20authored byMiao-Miao Wang, Tian-Zheng Xiong, Bo-Chen Chen, Jun-Jie Hu, He-Rui Wen, Sui-Jun Liu
Lanthanide-based metal–organic frameworks show
good potential
for applications due to their unique structures and functional properties.
A highly thermally and acid–base stable Eu-MOF was synthesized by a solvothermal method with the molecular formula
{[(CH3)2NH2]2[Eu2(NDDP)2(H2O)2]·H2O}n (Eu-MOF, H4NDDP = 5,5′-(naphthalene-2,6-diyl)diisophthalic acid). Eu-MOF takes a three-dimensional (4,4,8)-connected topology.
The water molecules involved in the coordination, free water molecules,
and [(CH3)2NH2]+ cations
in the pore can be used as proton carriers. The proton conductivity
attains 1.25 × 10–4 S cm–1 at room temperature and 2.42 × 10–3 S cm–1 at 70 °C and 98% relative humidity. Combined
with the dual-emission properties from the ligands and Eu(III) ions
enables Eu-MOF to be used as a ratiometric fluorescent
sensor for phosphate efficiently and rapidly, with a limit of detection
of 0.12 μM in the Tris–HCl buffer solution. These results
provide a new approach for the construction of MOFs with high proton
conductivity and a ratiometric fluorescence response.