Solvothermally synthesized pyrazoledicarboxylate incorporated Fe(II) MOF: Design, characterization, Hirshfeld studies, and mechanistic insight into fluorescent detection of mutagenic adulterant 2,4,6-trinitrophenol

Herein, an iron and 3,5-pyrazoledicarboxylic acid-based metal-organic framework (ZFeMOF) was successfully synthesized by utilizing the solvothermal method. The MOF was well characterized by different techniques like FTIR, single-crystal X-ray diffraction (s-XRD), powder X-ray diffraction (PXRD), and the intermolecular interactions present in the structure, and their contribution to Crystal packing were studied by Hirshfeld and Fingerprint plot study. Thereafter, the MOF was exploited for sensing environmentally hazardous nitroaromatic compounds (NACs) in the aqueous medium. The synthesized MOF was found to detect 2,4,6-trinitrophenol (TNP) judiciously among a host of nitroaromatic compounds. The mechanism involved in the selective detection of TNP was explored by taking into consideration evidentiary factors like the spectral overlap between emission spectra of MOF and absorption spectra of TNP and the lifetime decay profile of MOF. The emission spectrum of MOF and absorption spectrum of TNP showed maximum overlap with the value of overlap integral (J) equivalent to 5.70 x104 nm4/MCm. Furthermore, the lifetime of MOF decreased from 15.0 nanoseconds (ns) to 4.78 nanoseconds (ns) on the addition of TNP. Hence, based on these results, it was proposed that the mechanism involved in the detection of TNP is fluorescence resonance energy transfer (FRET) .