Amino-decorated lanthanide(iii) organic extended frameworks for multi-color luminescence and fluorescence sensing

Abstract

Solvothermal reactions of LnCl₃·6H₂O (Ln = Eu, Tb, Sm and Dy) with 2-aminoterephthalic acid obtain four isostructural lanthanide(III)–organic frameworks. The structure has the topology of a gadolinium 2-aminoterephthalic acid (MOF-LIC-1). The as-obtained samples were characterized by X-ray diffraction, FT-IR, TGA and luminescence spectroscopy. They all belong to the luminescence materials system with broad band excitation, which could extend to the visible-light region. The selected ligand could effectively sensitize the luminescence of Eu³⁺, Tb³⁺ and Sm³⁺, particularly the Eu³⁺ ions; thus, leading to the characteristic luminescence of Ln³⁺. More significantly, the white-light emission may be realized by a single-component Sm(III) framework. Furthermore, Eu-MOF was selected as a representative sample to examine the potential of the material for the sensing of metal ions. It showed highly selective and sensitive luminescence sensing for Al³⁺ ions. In addition, the luminescence color change can be easily distinguished with the naked eye under UV-light irradiation.