A luminescent Zn(ii) coordination polymer based on a new tetrazolyl–benzimidazolyl tripodal heterotopic ligand for detecting acetone and triethylamine in water

Abstract

A Zn(II) coordination polymer (CP), namely, {[Zn(DTPB)]·DMF}_n (H₂DTPB = 1-(3,5-di(2H-tetrazol-5-yl)phenyl)-1H-benzeimidazole, Zn-DTPB), was assembled from a new tetrazolyl–benzimidazolyl heterotopic triangular ligand. In Zn-DTPB, the tetrazolyl groups connect the Zn(II) ions into a 2D network with a (4·8²) topology, and the 2D network is further interconnected by Zn–N bonds between Zn(II) and benzimidazolyl groups to a 3D framework featuring a 4-connected sra topology. The DMF molecules were tightly encapsulated in the framework and could not be released until the framework decomposed. The framework is stable up to 300 °C and can be retained in water for 72 h. The luminescence in the solid-state and in various solvents was investigated, implying that Zn-DTPB can be used to detect acetone and triethylamine (TEA) in water by fluorescence quenching with good sensitivity and selectivity. Moreover, Zn-DTPB exhibited excellent reproducibility in sensing acetone. Mechanistic studies have shown that the fluorescence quenching of acetone and triethylamine is caused by competitive absorption and structural amorphization, respectively. Interestingly, the amorphous product can be transformed into Zn-DTPB crystals through a solvent-media structural transformation process.