Harvesting Bright Green Photoluminescence of Tb(BDC)(HO) MOF via Pressure-Modulated Ligand-to-Metal Energy Transfer.

Lanthanide metal-organic frameworks (Ln-MOFs) exhibit distinctive emission spectra and prolonged luminescent lifetimes, thereby offering a unique platform for the advancement of solid-state photoluminescence (PL) materials. However, the mismatch between the energy levels of metal ions and organic ligands leads to a weak PL emission. Herein, this study presents a pressure-treated strategy aimed at achieving efficient green PL in Tb(BDC)(HO) MOF. Compared to the initial intensity, the PL intensity is enhanced eightfold below 3.1 GPa. Intriguingly, the PL intensity of pressure-treated sample is amplified by 2.5-fold compared to the initial state, and the green emission monochromaticity is maintained. Experiments and calculations reveal that the enhanced hydrogen bonds are retained to the ambient conditions after pressure treatment. They lock the conjugated configuration formed between the planes of carboxyl group and benzene ring, facilitating the intersystem crossing. The reduced distances between metal ions and organic ligands drive the ligand-to-metal energy transfer process. This finding provided significant insights into structure-property relationship of Tb(BDC)(HO), offering a new platform for boosting emission enhancement in Ln-MOFs.