Tuning the Photoinduced Electron Transfer in a Zr‐MOF: Toward Solid‐State Fluorescent Molecular Switch and Turn‐On Sensor

• Published in: Advanced materials (Weinheim) Vol. 30; no. 34; pp. e1802329 - n/a
• Main Authors: Gui, Bo, Meng, Yi, Xie, Yang, Tian, Jianwu, Yu, Ge, Zeng, Weixuan, Zhang, Guanxin, Gong, Shaolong, Yang, Chuluo, Zhang, Deqing, Wang, Cheng
• Format: Journal Article
• Language: English
• Published: Germany Wiley Subscription Services, Inc 01-08-2018
• Subjects: Anthracene; Electron transfer; Fluorescence; fluorescent photoinduced electron transfer; Immobilization; Logic circuits; Metal-organic frameworks; Molecular machines; molecular switches; Sensors; Solid state; stimuli‐responsive metal‐organic framework; Switches; Tuning; turn‐on sensors; Zirconium; fluorescent photoinduced electron transfer; turn-on sensors; stimuli-responsive metal-organic framework; molecular switches; solid state
• ISSN: 0935-9648; 1521-4095
• DOI: 10.1002/adma.201802329

The immobilization of fluorescent photoinduced electron transfer (PET) switches/sensors into solid state, which usually cannot maintain their identical properties in solution, has remained a big challenge. Herein, a water‐stable anthracene and maleimide appended zirconium‐based‐metal–organic framework (Zr‐MOF; UiO‐68‐An/Ma) is reported. Unlike the regular intramolecular “fluorophore–spacer–receptor” format, the separated immobilization of fluorescent (anthracene) and acceptor (maleimide) groups into the framework of a multivariate MOF can also favor a pseudo‐intramolecular fluorescent PET process, resulting in UiO‐68‐An/Ma with very weak fluorescence. Interestingly, after Diels–Alder reaction or thiol‐ene reaction of maleimide groups, the pseudo‐intramolecular fluorescent PET process in UiO‐68‐An/Ma fails and the solid‐state fluorescence of the crystals is recovered. In addition, UiO‐68‐An/Ma shows an interesting application as solid‐state fluorescent turn‐on sensor for biothiols, with the naked eye response at a low concentration of 50 µmol L−1 within 5 min. This study represents a general strategy to enable the efficient tuning of fluorescent PET switches/sensors in solid state, and considering the fluorescence of the PET‐based MOFs can be restored after addition of analyte/target species, this research will definitely inspire to construct stimuli‐responsive fluorescent MOFs for interesting applications (e.g., logic gate) in future.
A solid‐state fluorescent photoinduced electron transfer (PET) switch/sensor: Unlike the regular intramolecular “fluorophore–spacer–receptor” format, the separated immobilization of fluorescent and acceptor groups into the framework of a crystalline porous multivarite metal–organic framework can also favor a pseudo‐intramolecular fluorescent PET process. Moreover, by tuning the electron‐accepting ability of the acceptor in the framework, the fluorescent PET switch/sensor can be efficiently tuned in the solid state.