Tuning the photoluminescence of lanthanide metal–organic framework nanospheres through ligand-induced phase transition towards sensing

Abstract

Luminescent lanthanide metal–organic framework (Ln-MOF) materials have recently attracted great attention in a diversity of frontier applications due to their nondestructive characterization, facile response and porous structure properties. However, the effect of structure transformation on the energy transfer processes and subsequently the photoluminescence properties has not been well investigated for Ln-MOF materials. Herein, we report a new type of ligand-induced lanthanide metal–organic framework (LI-Ln-MOF) nanosphere that yields tunable photoluminescence with an emission color change from magenta to yellow by adding or removing the water ligands. Further investigation suggests that the water molecules act as the newly attached secondary ligands to rebuild the MOF structure and then achieve tuning of the energy transfer from H₃BTC to Ln ions and between Tb³⁺ and Eu³⁺ ions. Based on the flexible addition and removal of the newly attached ligands, this material holds a great promise in MOF sensors and anti-counterfeiting. This study also helps gain a deep insight into the energy transfer in the Ln-MOF matrix, providing new possibilities for the development of multi-functional fluorescent sensing platforms.