Straw-sheaf-like terbium-based coordination polymer architectures: microwave-assisted synthesis and their application as selective luminescent probes for heavy metal ions

Abstract

Straw-sheaf-like terbium-based coordination polymer (CP) architectures have been successfully synthesized through a simple, facile and environmentally friendly microwave heating approach on a large scale in 15 min without the assistance of any template or surfactant employing 1,2,4,5-benzenetetracarboxylic acid (H₄BTC) as the organic building block. The composition and structure of the samples were well characterized by powder X-ray diffraction (XRD), elemental analyses (EA), Fourier transform infrared (FT-IR) spectroscopy, thermogravimetric analysis (TG), X-ray photoelectron spectroscopy (XPS), and scanning electron microscopy (SEM). The specific surface area was determined by the Brunauer–Emmett–Teller (BET) method. The measured specific surface area of the terbium-based CP was 152.51 m² g⁻¹. SEM results showed that the individual straw-sheaf has a length in the range of 70–90 μm and a middle diameter in the range of 5–8 μm. A possible mechanism responsible for the formation of the straw-sheaf-like hierarchical architectures was proposed. The products showed strong characteristics of green emissions under ultraviolet excitation, corresponding well to the ⁵D₄ → ⁷F_J transitions of Tb³⁺ ions. Furthermore, they displayed highly sensitive and selective luminescence quenching by Pb²⁺ in aqueous solution.