title: A novel fluorescence "on-off-on" chemosensor for Hg(2+)via a water-assistant blocking heavy atom effect.
abstract: Upper rim pyrene-functionalized hexahomotrioxacalix[3]arene L was synthesized via Click chemistry, and its fluorescence behaviors toward several common metal cations were investigated. L exhibited a significant fluorescence quenching response to Hg(2+) in CH3CN solution, which was unaffected by the coexistence of other competitive metal cations. Thus, L can be utilized as a highly selective and sensitive fluorescent chemosensor for Hg(2+) with a detection limit in the nM level. Interestingly, the quenched fluorescence emission can be successfully revived upon the addition of water. In this process, the heavy atom effect of Hg(2+) can be blocked by further coordination of a water molecule and resulted in the revival of the fluorescence emission of L/Hg(2+) complex. Particularly, other polar solvents such as CH3OH and CH3CH2OH also have the ability to revive the fluorescence emission of the L/Hg(2+) complex, but on a much smaller scale than observed for H2O. The heavy atom effect and blocking thereof were demonstrated within the same system by the use of a C3-symmetric homooxacalix[3]arene scaffold. The present studies provided further evidence for the blocking heavy atom effect.
authors.affiliation: Department of Applied Chemistry, Faculty of Science and Engineering, Saga University, Honjo-machi 1, Saga 840-8502, Japan. yamatot@cc.saga-u.ac.jp.
authors.forename: Chong
authors.initials: C
authors.lastname: Wu
authors.forename: Jiang-Lin
authors.initials: JL
authors.lastname: Zhao
authors.forename: Xue-Kai
authors.initials: XK
authors.lastname: Jiang
authors.forename: Chuan-Zeng
authors.initials: CZ
authors.lastname: Wang
authors.forename: Xin-Long
authors.initials: XL
authors.lastname: Ni
authors.forename: Xi
authors.initials: X
authors.lastname: Zeng
authors.forename: Carl
authors.initials: C
authors.lastname: Redshaw
authors.forename: Takehiko
authors.initials: T
authors.lastname: Yamato