Reconciling visible emission intensity and ON/OFF commutation ratio in photochromic lanthanide complexes of europium(III) and samarium(III)
Abstract
Developing highly emissive and photoswitchable lanthanide complexes for advanced anticounterfeiting materials requires overcoming a fundamental photophysical bottleneck: the intrinsic competition between the emission quantum yield (Φ em ) and the isomerization quantum yield (Φ closing ). Traditionally, maximizing photoconversion results in severely quenched, impractical ON-states. Here, we present a counter-intuitive molecular design strategy that deliberately lowers the isomerization quantum yield in favor of increasing the initial lanthanide emission while preserving a high ON-OFF intensity ratio. Using click-chemistry, we synthesized a unique ligand scaffold integrating a dithienylethene (DTE) photochrome with a pyridinebis(oxazoline) (pybox) antenna. Upon coordination, the resulting europium(III) and samarium(III) complexes exhibit a finely tuned moderate isomerization quantum yield (Φ closing = 0.25-0.27). This deliberate moderation preserves a very high emission in the ON-state, reaching a quantum yield of Φ em = 0.22 for the europium(III) complex, alongside a significant Φ em = 0.02 for the rarely investigated samarium(III) analogue. Despite their modest photoconversion, these systems maintain an important ON/OFF contrast with less than 10% residual luminescence at the photostationary state in solution. Finally, incorporating these complexes into PMMA polymer matrices leads to an optical modulation which is easy to detect with the naked eye, even in daylight, thus providing a robust framework for designing practically operative dynamic materials.
Versions
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BibTeX
@article{freroux2026reconciling,
title = {{Reconciling visible emission intensity and ON/OFF commutation ratio in photochromic lanthanide complexes of europium(III) and samarium(III)}},
author = {Yoann Fréroux and Salauat Kiraev and Marie Dallon and Olivier Maury and Stéphane Rigaut and Lucie Norel},
journal = {Inorganic Chemistry Frontiers},
year = {2026},
month = oct,
doi = {10.1039/d6qi01446a},
url = {https://hal.science/hal-05781353v1},
note = {CC BY},
}
RIS
TY - JOUR
TI - Reconciling visible emission intensity and ON/OFF commutation ratio in photochromic lanthanide complexes of europium(III) and samarium(III)
AU - Yoann Fréroux
AU - Salauat Kiraev
AU - Marie Dallon
AU - Olivier Maury
AU - Stéphane Rigaut
AU - Lucie Norel
PY - 2026
DA - 2026/10/06
JO - Inorganic Chemistry Frontiers
DO - 10.1039/d6qi01446a
UR - https://hal.science/hal-05781353v1
AB - Developing highly emissive and photoswitchable lanthanide complexes for advanced anticounterfeiting materials requires overcoming a fundamental photophysical bottleneck: the intrinsic competition between the emission quantum yield (Φ em ) and the isomerization quantum yield (Φ closing ). Traditionally, maximizing photoconversion results in severely quenched, impractical ON-states. Here, we present a counter-intuitive molecular design strategy that deliberately lowers the isomerization quantum yield in favor of increasing the initial lanthanide emission while preserving a high ON-OFF intensity ratio. Using click-chemistry, we synthesized a unique ligand scaffold integrating a dithienylethene (DTE) photochrome with a pyridinebis(oxazoline) (pybox) antenna. Upon coordination, the resulting europium(III) and samarium(III) complexes exhibit a finely tuned moderate isomerization quantum yield (Φ closing = 0.25-0.27). This deliberate moderation preserves a very high emission in the ON-state, reaching a quantum yield of Φ em = 0.22 for the europium(III) complex, alongside a significant Φ em = 0.02 for the rarely investigated samarium(III) analogue. Despite their modest photoconversion, these systems maintain an important ON/OFF contrast with less than 10% residual luminescence at the photostationary state in solution. Finally, incorporating these complexes into PMMA polymer matrices leads to an optical modulation which is easy to detect with the naked eye, even in daylight, thus providing a robust framework for designing practically operative dynamic materials.
SN - 2052-1545
SN - 2052-1553
ER -