Construction of a zeolite A-type multivariate metal–organic framework for selective sensing of Fe3+ and Cr2O72−

Abstract

Construction of zeolite-type frameworks is of broad interest and mainly achieved by using imidazolate linkers. Incorporation of multiple linkers/functionalities into these unique types of frameworks would potentially expand their application scope. Herein, a three-dimensional (3D) metal–organic framework, BUT-27, with a unique zeolite A structure (LTA topology) was synthesized by linker exchange via single-crystal-to-single-crystal transformation. Addition of isophthalic acid linker to the two-dimensional double layered BUT-25 changed the whole framework to a 3D structure, BUT-27, containing three kinds of linkers. The strong fluorescence and presence of free O and N atoms in the framework make BUT-27 a good luminescent sensor for the detection of Fe³⁺ and Cr₂O₇²⁻ ions with high selectivity and sensitivity, i.e. K_sv = 1.1 × 10⁴ and 5.9 × 10⁴, and LOD (limit of detection) of 0.19 and 0.26 μM, respectively. These values are lower than the minimum values specified by US-EPA (United States Environmental Protection Agency) indicating its high potential for practical applications.