Seven Ln(<scp>iii</scp>) coordination polymers with two kinds of geometric coordination but the same 3D topological property: luminescence sensing and magnetic property

Abstract

Two series of seven lanthanide metal coordination polymers (Ln-CPs) formulated as {[Ln(dttpa)_1.5(H₂O)₂]·H₂O}_<i>n</i> [Ln = La³⁺ (1), Ce³⁺ (2), Nd³⁺ (3), Sm³⁺ (4) and Eu³⁺ (5)] and {[Ln (dttpa)_1.5(H₂O)]·<i>x</i>H₂O}_<i>n</i> [Ln = Tb³⁺ (6) and Er³⁺ (7), <i>x</i> = 0.75] have been successfully constructed using Ln³⁺ ions and 2,5-di(1<i>H</i>-1,2,4-triazol-1-yl)terephthalic acid (H₂dttpa) <i>via</i> a hydrothermal method. Their 3D structures are fully characterised by Fourier transform infrared (FT-IR) spectroscopy, X-ray single-crystal analyses, powder diffraction analyses (PXRD), elemental analyses (EAs) and thermogravimetric analyses (TGAs). All Ln-CPs display the same topological property with the point symbol of {4²·8⁴}{4⁴·6²}₂{4⁹·6⁶}₂, and crystallize in the triclinic space group <i>P</i>1̄. Interestingly, Eu-CP (5) effectively sensitizes the visible emission of Tb³⁺ and shows high selectivity and stable response with the lowest detection limit of 9.88 nM. Furthermore, Tb-CP (6) acts as a good luminescence sensor to detect nitrobenzene (NB) with a detection limit of 12.5 nM. In addition, the magnetic susceptibility measurement for Er-CP (7) further shows that compounds constructed by dttpa^2- are a kind of promising functional material.