By using solvothermal method, a one-dimensional chain compound [KEu₂(FDCA)₃(H₂O)₉·0.5(FDCA)] (1) was synthesized. Single-crystal X-ray diffraction data reveal that 1 crystallizes in monoclinic system, space group P2₁/n with a = 12.1996(1), b = 18.6454(2), c = 17.7123(2) Å, β = 98.8460(10)°, D_c = 1.753 g/cm³, Z = 2, V = 3981.03(7) ų, R = 0.0544 and wR = 0.1511 for 7886 observed reflections with I > 2σ(I). In 1, three FDCA^2– ligands construct a “23-crown-9-like” structure as the second building units (SBUs) to further form an infinite 1D chain. Meanwhile, the fluorescent result reveals that compound 1 can selectively and sensitively sense Fe³⁺ by the fluorescence quenching.