A highly sensitive and selective turn-off fluorescence sensor for Fe3+ detection based on a terbium metal-organic framework

Highlights: • Tb-MOF is a turn-off fluorescence sensor for Fe³⁺ with high sensitivity, selectivity, rapid response and durability. • Its sensitivity test indicates a low LOD of 0.936μM. • The selectivity test of Tb-MOF to Fe³⁺ shows no inference found within twenty selected interferents. A hydrothermal reaction of 1,3-di(3′,5′-dicarboxylphenyl)benzene (H₄ddb) with Tb³⁺ gave out a metal-organic framework material (Tb-MOF). Tb-MOF emitted green fluorescence, assigned to the characteristic transitions ⁵D₄→⁷F_J (J=6–3) of Tb³⁺. Screening detected metal cations indicated that only Fe³⁺ can completely quench the fluorescence of Tb-MOF in the twenty optional ions. The sensitivity test of Tb-MOF showed a linear response of I₀/I=55.2061∙C_Fe3+ + 1.24077 in the C_Fe3+ range of 3.3×10⁻⁴-0.033mmolL⁻¹ with LOD being 0.936μM. Sixteen metal cations and four anions in the selectivity test did not influence the detection performances of Tb-MOF to Fe³⁺. The emission intensities of ⁵D₄→⁷F₅ at 545nm of Tb³⁺ can basically be recovered during a four-time quenching-recovery cycle in the durability test. Tb-MOF is a quantitative turn-off fluorescence sensor to Fe³⁺ detection with high sensitivity and selectivity, rapid response and a certain durability.