An Europium (III) Luminophore with Pressure‐Sensing Units: Effective Back Energy Transfer in Coordination Polymers with Hexadentate Porous Stable Networks
Yasuchika Hasegawa, Takuya Sawanobori, Yuichi Kitagawa, S. Shoji, Koji Fushimi, Yuta Nakasaka, Takao Masuda, Ichiro Hisaki
Abstract
Abstract A luminescent Eu III coordination polymer with O 2 ‐sensing units under air, Eu III ‐hcpt (hcpt: 2,3,6,7,10,11‐hexakis(4‐carboxy‐phenyl)triphenylene), is reported. The hexadentate carboxylic acids in hcpt ligands play an important role in the formation of tight‐packed three‐dimensional networks in Eu III ‐hcpt, giving hyper thermo‐stable structures (decomposition temperature=420 °C). The three‐dimensional porous network promotes bright luminescence (4f–4f emission quantum yield=70 %). The emission lifetime of Eu III ‐hcpt under vacuum (0.86 ms) was twice as large as that under O 2 (0.48 ms, 1 atom:101.3 kPa). The Arrhenius analysis of the emission decay profile indicates that the back energy transfer (BEnT) from the emitting level of the europium(III) ion to the excited T 1 state of the hcpt ligand should be activated at room temperature. The gradual decrease of emission lifetime is caused by the BEnT process in Eu III ‐hcpt. Finally, an advanced pressure‐sensitive luminophore is demonstrated.