posted on 2020-03-17, 14:36authored byDongyang Xu, Long Chen, Xing Dai, Baoyu Li, Yaxing Wang, Wei Liu, Jie Li, Yi Tao, Yanlong Wang, Yong Liu, Guowen Peng, Ruhong Zhou, Zhifang Chai, Shuao Wang
Contamination
of 99TcO4–, a problematic
radioactive anion in the nuclear fuel cycle, in groundwater
has been observed in a series of legacy nuclear sites, representing
a notable radiation hazard and environmental concern. The development
of convenient, rapid, and sensitive detection methods is therefore
critical for radioactivity control and remediation tasks. Traditional
detection methods suffer from clear demerits of either the presence
of large interference from coexisting radioactive species (e.g., radioactivity
counting methods) or the requirement of extensive instrumentation
and analysis procedure (e.g., mass spectrometry). Here, we constructed
a luminescent iridium(III) organometallic complex (Ir(ppy)2(bpy)+; ppy = 2-phenylpyridine, bpy = 2,2′-bipyridine)-grafted porous aromatic framework (Ir-PAF) for the first
time, which can be utilized for efficient, facile, and selective detection
of trace ReO4–/TcO4– in aqueous solutions. Importantly, the luminescence intensity of
Ir-PAF is greatly enhanced in the presence of ReO4–/TcO4–, giving rise to
a distinct turn-on sensor with the detection limit of 556.9 μg/L.
Such a superior detection capability originates from the highly selective
and strong interaction between ReO4–/TcO4– and Ir(ppy)2(bpy)+, leading to an efficient pre-enrichment of ReO4–/TcO4– during analysis and subsequently
a much weaker nonradiative decay of the luminescence of Ir(ppy)2(bpy)+, as illustrated by density functional theory
(DFT) calculation as well as quantum yield and fluorescence lifetime
measurements. Successful quantification of trace ReO4– in simulated Hanford low-activity waste (LAW) solution
containing large excess of Cl–, NO3–, and NO2– was demonstrated,
highlighting the bright future of luminescent PAFs in the area of
chemical sensing.