Sonochemically synthesized Zn (II) and Cd (II) based metal-organic frameworks as fluoroprobes for sensing of 2,6-dichlorophenol

Abstract

A sonochemical route for the synthesis of 2-D Zn (II) and Cd (II) based metal - organic frameworks (MOF) formulated as [Zn(apca)2]n and [CdCl2(apca)]n (Hapca ​= ​3-aminopyrazine-2-carboxylic acid) was developed. The MOFs synthesized were characterized using PXRD, FT-IR, SEM, and TGA analysis. The impact of different irradiation time and precursor concentration were investigated for attaining repetitious morphology. The DFT studies provide the detailed calculation of charge density distribution and electron localization function (ELF) of MOFs. The selectivity of the as-synthesized MOFs was studied for detecting phenolic structural analogs such as phenol, 2,6-dichlorophenol (2,6-DCP), 2,4-dichlorophenol (2,4-DCP), 4-chlorophenol (4-CP), 2-Chlorophenol (2-CP), 2,4,6-trichlorophenol(2,4,6-TCP), 2-methoxyphenol (2-MP), 2-nitrophenol (2-NP), and 4-hydroxyphenol (4-HP) out under optimal conditions. The results revealed that our proposed probes are equipped with excellent recognition ability for almost exclusively 2,6-DCP. Both the MOFs exhibit a good linearity between the fluorescence intensity and analyte concentration in the range of 2–30 ​μmol ​L−1. The calculated limit of detection (LOD) for Zn-MOF and Cd-MOF was 5.6 ​μmol ​L−1 and 2.2 ​μmol ​L−1, respectively. The studies were further extended to fabrication of Zn-MOF@chitosan and Cd-MOF@chitosan membranes and proposed as solid fluoroprobes for detection of 2,6-DCP in real sample analysis.