2D → 3D polycatenated Zn(ii) metal–organic framework with good chemical stability as a fluorescent sensor toward salicylaldehyde, acetylacetone and H2PO4−

Abstract

A new Zn(II) metal–organic framework (MOF) with the formula [Zn(BBIP)(2,6-NDC)]_n (JXUST-44, BBIP = 3,5-bis(1H-benzo[d]imidazol-1-yl)pyridine and 2,6-H₂NDC = 2,6-naphthalic acid) was synthesized under solvothermal conditions. The adjacent Zn(II) ions are connected by BBIP ligands to form one-dimensional (1D) chains, which are further linked by carboxylate groups of 2,6-NDC²⁻ ligands to obtain a two-dimensional layer structure, resulting in a 2D → 3D polycatenated MOF. JXUST-44 can be simplified as a 4-connected sql topology and shows good chemical stability in a wide pH range from 2 to 12 at room temperature. The fluorescence experiments indicate that JXUST-44 presents sensitive and selective detection of salicylaldehyde (SA), acetylacetone (acac) and H₂PO₄⁻ with the detection limits of 0.074, 10.311 and 0.011 ppm, respectively. It is worth noting that JXUST-44 shows turn-on fluorescence toward acac and H₂PO₄⁻, as well as good recyclability and stability for acac, SA and H₂PO₄⁻. Therefore, JXUST-44 can be considered as a good fluorescent sensor for acac, SA and H₂PO₄⁻. The sensing mechanism has also been studied in detail.