High-performance functionalized flexible aerogel fluorescent probe based on dual-ligand Eu-MOF for highly sensitive detection of copper ions

Constructing dual-ligand Eu-MOF fluorescent probes to improve the characteristic luminescence of Eu 3+ . • Developing an Eu-MOF aerogel system with selective recognition, sensitive detection, and flexible features. • Investigating the fluorescence quenching mechanism of Eu-MOF. • Achieving a Cu 2+ detection limit of 0.775 × 10 −6 M with potential applicability in real polluted water samples. Given the hazards of metal ions and the difficulties in recycling and agglomeration of rare earth metal–organic framework (MOFs) powders, this study constructs a flexible aerogel fluorescence sensing platform based on dual-ligand Eu-MOF for highly sensitive detection of Cu 2+ . Eu-MOF exhibits outstanding fluorescence sensing performance by virtue of sharp emission bands, large Stokes shift and excellent photostability, combined with coordination environment modulation via dual ligands. Immobilizing such MOF into a 3D aerogel network can effectively overcome the drawbacks of poor processability, easy agglomeration and difficult recovery of MOF powders while preserving their intrinsic luminescence properties. The results show that Eu-MOF can be uniformly loaded onto the pore wall surface of PVA/k-CG/SA aerogel without significantly affecting its original luminescence properties. The obtained PVA/k-CG/SA/Eu-MOF aerogel exhibited a well-developed porous architecture and good mechanical robustness, after 10 cycles of compression at 60 % strain, the maximum compressive stress still reaches 12.08 kPa. Furthermore, the material exhibits the highest luminescence intensity when the mass ratio of Eu-MOF to DPA is 1:2, further increasing the Eu-MOF content leads to fluorescence attenuation due to concentration quenching effects dominated by electric dipole-electric dipole interactions. Under optimized detection conditions, this aerogel demonstrates a significant and excellent selective fluorescence quenching response to Cu 2+ , with a detection limit as low as 0.775 × 10 −6 M. This study provides a feasible strategy for constructing flexible, recyclable, and processable rare-earth MOFs macroscopic fluorescent sensing materials and demonstrates their application potential in environmental monitoring.