Different effects in the selective detection of aniline and Fe3+ by lanthanide-based coordination polymers containing multiple reactive sites

Abstract

In this paper, three isostructural 1D lanthanide complexes, [Ln(dppc)(H₂O)₄]_n·2nH₂O (Ln = Eu, Tb and Eu_0.501Tb_0.499, named 1-Eu, 2-Tb and Eu_0.501Tb_0.499), based on 3-(2,4-dicarboxylate phenyl)-2-pyridinecarboxylic acid (H₃dppc) have been synthesized and characterized by elemental analysis, IR, PXRD, TG and X-ray crystallography. The complexes exhibit a 1D chain structure, which is further linked into a 3D supramolecular framework by hydrogen bonds. Tuneable emission colour of Eu_0.501Tb_0.499 is realized by adjusting the excitation wavelength. The sensing properties of 1-Eu and 2-Tb towards Fe³⁺ and aniline indicate that the two complexes have almost the same superior sensitivity and low detection limit for Fe³⁺ in aqueous solution, while they have different detection abilities for aniline in DMF solvent. The different detection abilities were discussed by means of PXRD, UV-vis, luminescence lifetimes and molecular surface calculations (Hirshfeld surface analysis and 2D fingerprint plots).