Dual Cu(II)-Based Functional MOFs with Fluorescent Sensing Capability toward Fe³⁺ and CrO₄²⁻ Ions

In this work, two Cu(II)-based coordination polymers, [Cu(oba)(bpta)]·(DMF)₂ (CP1) and [Cu(oba)(bpfb)]·(DMF)₂ (CP2), were synthesized via a mixed-ligand solvothermal method using 4,4'-oxybisbenzoic acid (H₂oba) and bis-pyridyl co-ligands. Both CPs exhibit strong solid-state fluorescence and excellent water stability. CP1 shows high selectivity for Fe³⁺ with a K_SV of 2.63 × 10⁵ M⁻¹ and LOD of 0.37 μmol·L⁻¹, while CP2 is highly sensitive to CrO₄²⁻ with a K_SV of 1.47 × 10⁵ M⁻¹ and LOD of 0.65 μmol·L⁻¹. Both materials demonstrate reversible fluorescence quenching over multiple cycles. These results indicate that CP1 and CP2 are promising luminescent probes for the sensitive and recyclable detection of environmentally hazardous ions, offering potential for real-time water quality monitoring.