Maximized Green Photoluminescence in Tb‐Based Metal–Organic Framework via Pressure‐Treated Engineering

Abstract

Lanthanide metal-organic frameworks are of great interest in the development of photoluminescence (PL) materials owing to their structural tunability and intrinsic features of lanthanide elements. However, there exists some limitations arising from poor matching with metal ions, thereby exhibiting a weak ligand-tometal energy transfer (LMET) process. Here we demonstrate a pressure-treated strategy for achieving high PL performance in green-emitting Tb(BTC)(H 2 O) 6 . The PL quantum yield of pressure-treated sample increased from 50.6 % to 90.4 %. We found that the enhanced hydrogen bonds locked the conjugated configuration formed by two planes of carboxyl group and benzene ring, enabling the promoted intersystem crossing to effectively drive LMET. Moreover, the optimized singlet and triplet states also validated the facilitated LMET process. This work opens the opportunity of structure optimization to improve PL performance in MOFs by pressure-treated engineering.

Stretchable Tb–Tb Distance Regulates the Piezofluorochromic Behavior of Chiral Tb(III)-MOF upon Compression

“…This is due to the fluorescence of Tb-MOF from the characteristic emission transition of 5 D 4 → 7 F J (J = 3−6) of the Tb(III) ions with a fixed band-gap energy. 43 This reversible shrinkage of the coordination environment around Tb(III) ions was further demonstrated by the in situ high-pressure FT-IR spectra (Figure S15), where the major absorption peaks in the range of 1800−1250 cm −1 were studied in detail. No obvious new peaks or shoulder peaks were observed with the pressure up to 9.7 GPa, and only a minor blue shift was found (Figure S15).…”

“…For Tb-MOF under compression, the absorption indicated an obvious red shift, while the fluorescence remained unchanged. This is due to the fluorescence of Tb-MOF from the characteristic emission transition of 5 D 4 → 7 F J ( J = 3–6) of the Tb­(III) ions with a fixed band-gap energy …”

“…Compared to the other reported MOFs, Tb-MOF possessed ultrastable mechanical stability (Figure and Table S8). ,,,,,− …”

“…Moreover, no shift of the luminescent wavelength was observed during the whole compressing–decompressing process for Tb-MOF , which was ascribed to the characteristic luminescence from the Tb element ( Figure S9 ). 43 The typical light-emitting materials were usually organic molecules, where the emission intensity changes under high-pressure compression were mainly due to the enhanced intermolecular interactions.…”

“…This is due to the fluorescence of Tb-MOF from the characteristic emission transition of 5 D 4 → 7 F J ( J = 3–6) of the Tb(III) ions with a fixed band-gap energy. 43 …”