A cobalt-organic framework with sensitive detection of Fe3+, Cr2O72–, and CrO42– ions in water

Abstract

A six-coordinated 3D metal–organic framework (MOF), namely, [Co(BPDC)(3-bpdb)(H2O)2]n (1) (H2BPDC = 4,4′-biphenyldicarboxylic acid, 3-bpdb = 1,4-bis(3-pyridyl)-2,3-diaza-1,3-butadiene) was purposefully constructed and characterized by single-crystal XRD, IR, elemental analyses, PXRD, SEM, and TGA. Crystal structural analysis revealed that the complex consists of a cds-type three-fold interpenetrated framework. Hirshfeld surface analysis yielded details of the surface characteristics of 1. Significant O−H···O hydrogen bonding interactions, which could promote the stability of the framework, were found is extremely stable in aqueous solution and can resist acids and bases over an extensive pH range of 2 - 13. 1 shows brilliant fluorescent emission in the solid state and in aqueous solution. Fluorescence titration, cyclic, and anti-interference experiments demonstrated that 1 is an excellent probe for Fe3+, CrO42‒ and Cr2O72‒ in water. The Ksv values of 1 for Fe3+, CrO42‒, and Cr2O72‒, which were as high as 1.06 × 104 M−1, 1.50 × 104 M−1, and 1.16 × 104 M−1, respectively, were comparable with those of other sensors. The quenching mechanism of the novel probe was subsequently explained.