title: Coumarin-modified microporous-mesoporous Zn-MOF-74 showing ultra-high uptake capacity and photo-switched storage/release of U(VI) ions.
abstract: Driven by an energy crisis but consequently puzzled by various environmental problems, uranium, as the basic material of nuclear energy, is now receiving extensive attentions. In contrast to numerous sorbents applied in this field, metal-organic framework (MOFs), as a renovated material platform, has only recently been developed. How to improve the adsorption capacity of MOF materials towards U(VI) ions, as well as taking advantage of the nature of these MOFs to design photo-switched behaviour for photo-triggered storage/release of U(VI) ions are at present urgent problems and great challenges to be solved. Herein, we show a simple and facile method to target the goal. Through coordination-based post-synthetic strategy, microporous- mesoporous Zn-MOF-74 was easily functionalized by grafting coumarin on coordinatively unsaturated Zn(II) centers, yielding a series of coumarin-modified Zn-MOF-74 materials. The obtained samples displayed ultra-high adsorption capacity for U(VI) ions from water at pH value of 4 with maximum adsorption capacities as high as 360 mg/g (the record value in MOFs) and a remarkable photo-switched capability of 50 mg/g at pH value of 4. To the best of knowledge, and in contrast to the well-known photo-switched behaviour towards CO2, dye (propidium iodide), as well as fluorescence observed in MOFs, this is the first study that shows a photo-switched behaviour towards radioactive U(VI) ions in aqueous solution.
authors.affiliation: State Key Laboratory for Nuclear Resources and Environment, and School of Biology, Chemistry and Material Science, East China University of Technology, Nanchang, Jiangxi 344000, China.
authors.forename: Le
authors.initials: L
authors.lastname: Zhang
authors.affiliation: State Key Laboratory for Nuclear Resources and Environment, and School of Biology, Chemistry and Material Science, East China University of Technology, Nanchang, Jiangxi 344000, China.
authors.forename: Lin Lin
authors.initials: LL
authors.lastname: Wang
authors.affiliation: State Key Laboratory for Nuclear Resources and Environment, and School of Biology, Chemistry and Material Science, East China University of Technology, Nanchang, Jiangxi 344000, China.
authors.forename: Le Le
authors.initials: le L
authors.lastname: Gong
authors.affiliation: State Key Laboratory for Nuclear Resources and Environment, and School of Biology, Chemistry and Material Science, East China University of Technology, Nanchang, Jiangxi 344000, China.
authors.forename: Xue Feng
authors.initials: XF
authors.lastname: Feng
authors.affiliation: State Key Laboratory for Nuclear Resources and Environment, and School of Biology, Chemistry and Material Science, East China University of Technology, Nanchang, Jiangxi 344000, China.
authors.forename: Ming Biao
authors.initials: MB
authors.lastname: Luo
authors.affiliation: State Key Laboratory for Nuclear Resources and Environment, and School of Biology, Chemistry and Material Science, East China University of Technology, Nanchang, Jiangxi 344000, China. Electronic address: ecitluofeng@163.com.
authors.forename: Feng
authors.initials: F
authors.lastname: Luo
keywords: Coumarin; Hybrid material; MOF; Photo-switching behaviour; U(VI) uptake