Fluorescent Zn(ii) frameworks with multicarboxylate and pyridyl N-donor ligands for sensing specific anions and organic molecules

Abstract

Three novel fluorescent Zn(II) frameworks, namely [Zn(DPA)(NDA)]₂·2DMF (1), [Zn₂(DPA)(OBA)₂]·2DMF·4H₂O (2) and [Zn(DPA)(HNTB)]·H₂O (3) (DPA = 2,5-di(pyridin-4-yl)aniline, H₂NDA = 1,4-naphthalenedicarboxylic acid, H₂OBA = 4,4′-oxydibenzoic acid, H₃NTB = 4,4′,4′′-nitrilotribenzoic acid, DMF = N,N-dimethylformamide), were successfully fabricated and structurally characterized. Due to the variety of organic linkers, 1–3 exhibit varied topologies: 1 is a 4-c three-dimensional (3D) framework with {6⁵·8} topology, 2 is a 6-c 3D net with point symbol of {4⁴·6¹⁰·8}, and 3 is a 4-c two-dimensional network that further stacks into a 3D structure by hydrogen bonding interactions with {4⁴·6²} topology. Experiments related to fluorescence show that 1–3 can be utilized to quickly identify specific anions of CrO₄²⁻/Cr₂O₇²⁻, and organic molecules such as 2,4,6-trinitrophenol and benzaldehyde.