Pyrimidine hydrazide-like Zn(II) coordination polymer as a fluorescent chemosensor for selective, sensitive and practice detection of 2,4-DNP and 4-NP

Abstract

Unusual luminescent zinc (II) coordination polymer (Zn (II)-CP) was synthesized from a new pyrimidine hydrazide (H₂L, N′- (pyrimidin-2-yl) benzo hydrazide) as a principal ligand and characterized by elemental analysis, infrared spectroscopy, and single-crystal X-ray diffraction. The Zn (II)-CP ([Zn₃(HL)₂Cl₄]_n) belonging to monoclinic crystal system with space group of P2₁/n, where the chelate ring structure was formed with the intervention strategy of the tetradentate ligand (HL⁻)and a one-dimensional (1D) infinite chain-shaped structure was also created by bridging Cl⁻ ligands. Zn(II)-CP displays the observed red emission with the maximum peak at 625 nm in solid state upon excitation at 300 nm. Subsequently, 2,4-dinitrophenol (2,4-DNP) / 4-nitrophenol (4-NP) in aqueous solution was identified and detected by the change of fluorescence intensity of Zn(II)-CP, and the K_sv value was 4.7402 × 10⁴ M⁻¹ / 5.5739 × 10⁴ M⁻¹. The calculated recovery rates in different water from nature were 100.07–100.46 % for 2,4-DNP and 99.89–101.50 % for 4-NP, which provides a new analytical approach for monitoring of 2,4-DNP and 4-NP in natural water. In addition, the binding detection mechanism of the complex towards 2,4-DNP or 4-NP were analyzed by PXRD diffraction, spectral experiments and theoretical calculation(DFT).