Metal-regulated d10 coordination polymers constructed from bis(pyridyl)-bis(amide) ligands with different spacers as high-efficiency fluorescence sensors for identifying chlortetracycline and furaltadone

Abstract

The detection of antibiotics is still the focus of global attention, because their abuse can lead to biological hazards. Herein, three new coordination polymers as fluorescent sensors, namely [Cd₃(L1)(MTC)₂(H₂O)₆] (CP 1), [Zn(L1)(HMTC)·2H₂O] (CP 2) and [Cd₃(L2)(MTC)₂(H₂O)₆] (CP 3) [H₃MTC = trimellitic acid, L1 = (E)-4,4′-(ethene-l,2-diyl)bis(N-pyridin-3-yl)benzamide) and L2 = (E)-4,4′-(diazene-1,2-diyl)bis(N-(pyridin-3-yl)benzamide)], were synthesized by using two bis(pyridyl)-bis(amide) ligands with different spacers and trimellitic acid mixed ligands under hydrothermal conditions, which were structurally characterized by single crystal X-ray diffraction, PXRD and IR. CP 1 and CP 3 have similar 2D coordination networks and 3D supramolecular structures, while CP 2 is a 2D coordination structure formed by alternatively linking 1D chains of Zn-L1 and Zn-HMTC, which is further extended to a 3D supramolecular framework. In addition, CPs 1–3 can highly efficiently detect two classes of antibiotics, chlortetracycline and furaltadone, with low LODs, excellent anti-interference ability, pH stability and recyclability. In CPs 1–3, CP 1 has the lowest LOD (5.12 × 10⁻⁸ M for CTC and 9.41 × 10⁻⁸ M for FTD). The sensing mechanisms, and the influences of composition and structure differences on the performances are discussed. The results provide a reasonable experimental reference for designing CPs and understanding the influencing factors of fluorescence performances.