Rational Synthesis of a Stable Rod MOF for Ultrasensitive Detection of Nitenpyram and Nitrofurazone in Natural Water Systems

Overuse of nitenpyram and nitrofurazone in agricultural
products
poses enormous risks to ecosystems, and effective detection and quantification
of these residual pollutants are of great concern. Although several
strategies have been established for detecting nitenpyram and nitrofurazone
in water, searching for a new sensor material with great sensitivity,
selectivity, and recyclability remains challenging. Here, we design
and synthesize a stable metal–organic framework (MOF) (Zn-CPTA) by employing an organic linker based on the coordination
features of benzene-1,4-dicarboxylate and picolinic acid. Zn-CPTA is a 3D framework built from Zn–O–Zn chains called
rod secondary building units, which contains 1D open channels modified
by uncoordinated carboxyl O atoms and exhibits impressive chemical
stability in aqueous solutions within a pH range from 2 to 12. Especially,
fluorescent Zn-CPTA can quickly and sensitively detect
nitenpyram and nitrofurazone in aqueous solutions with a high quenching
constant and low detection limit (LOD) (KSV values for nitenpyram and nitrofurazone are 1.67 × 104 and 1.02 × 105 M–1 with LOD of
0.625 and 0.126 μM, respectively), as well as outstanding selectivity
and recyclability. Notably, the LOD value is the lowest among the
reported MOFs used for nitrofurazone detection. Besides, experiments
and density functional theory calculations are combined to explain
the quenching mechanism. Finally, the practical application of Zn-CPTA was further explored in real environment samples with
satisfactory recoveries.