Hazardous 2,4,6-Trinitrophenol (TNP) Detection in Water by Amine and Azine Functionalized Metal-Organic Framework

A Zn(II)-based metal-organic framework (MOF) decorated with amine and azine functionalities, TMU-17-NH₂ (formulated as [Zn(H2ata)(L)].2DMF; L = 1,4-bis(4-pyridyl)-2,3-diaza-2,3-butadiene and H₂ata = 2-aminoterephthalic acid) has been successfully synthesized via a solvothermal method. According to crystallographic studies, the synthesized TMU-17-NH₂ has three dimensional cuboidal structure with the pore surface decorated with free amine (-NH2) and azine (= N-N =) functional groups. The photoluminescence investigations proved that the synthesized MOF can be effectively utilized for selective detection of 2,4,6-trinitrophenol (TNP) in water with an apparent turn-off quenching response. Its limits of detection (LOD) for TNP was 9.4 ppb and competitive nitro explosive testing confirmed its higher selectivity towards TNP (over other nitro explosives). Calculations based on density functional theory (DFT) and spectrum overlap were utilized to evaluate the sensing mechanisms. This MOF-based fluorescence sensing technique for TNP had a high sensitivity (K_sv = 3.26 × 10⁴ M^-1).