Preparation of tetra-imidazolium salt and sensing for fluoride anion.

One tetra-imidazolium salt (2) based on quinoxaline was prepared and characterized, and the detection of anions by compound 2 as a chemosensor was researched through fluorescence spectra, UV/Vis spectra, 1H NMR titrations, MS and IR spectra. The experimental results displayed that sensor 2 can selectively recognize F− through the instrument or the naked eyes (the color changed from colorless to brown in visible light). The high K value (6.4 × 104 M−1) for 2 F− indicated that 2 had strong bonding force to F−. The low detection limit (1.84 × 10−7 mol/L) indicated that the detection of F− by 2 was sensitive. One tetra-imidazolium salt was prepared, and its selective recognition for F- was investigated. [Display omitted] • A new tetra-imidazolium salt based on quinoxaline (2) was prepared and characterized. • The selective recognition of 2 to fluoride ion was investigated. • Compound 2 had high sensitivity for the detection of F− with the detection limit of 1.84 × 10−7 M mol/L. • The association constant of 2 F− was 6.4 × 104 M−1, which indicated that 2 had strong bonding force to F−. [ABSTRACT FROM AUTHOR]