Intercalation of lanthanide cations to a layer-like metal–organic framework for color tunable white light emission

Abstract

One gallium carboxylate of MOF (Ga₂(OH)₄(C₉O₆H₄) or MIL-124) has been synthesized by a facile solvothermal approach, and the luminescence was tuned by encapsulating lanthanide(III)(Ln³⁺) cations into the channels through the active-COOH group in MIL-124 post-synthesis. PXRD, TEM, FTIR, and TGA were performed to determine the structure and thermal stability of the obtained products. The photophysical properties of these Ln³⁺ incorporated products are studied in detail, whose luminescent color can be tuned by controlling the composition of different Ln³⁺ cations in MOF. Furthermore, with careful adjustment of the excitation wavelength and concentration of the Ln³⁺ cations, the color of the luminescence can be modulated, and dichromatic (MIL-124@Eu³⁺) and trichromatic (MIL-124@Eu³⁺/Tb³⁺) white-light-emission can indeed be achieved. One of the optimized chromaticity coordinates in white-light-emission is (0.3693, 0.3362) which is very close to the value for ideal white-light (0.333, 0.333). The versatile luminescence, good thermal stability, and compatibility with aqueous conditions reveal that these materials based on MOF may have some potential applications in luminescent devices for display or lighting.