Ferrocene appended fluorescein-based ratiomeric fluorescence and electrochemical chemosensor for Fe3+ and Hg2+ ions in aqueous media: Application in real samples analysis

摘要

A novel visually detectable fluorescein-based chemosensor (4) containing a ferrocene backbone has been designed and synthesized successfully by simultaneously introducing ferrocene with an azide appendage and fluorescein with an alkyne functional group via a [2 + 3] cycloaddition reaction. Further, its sensing response towards various metal cations was examined via multiple channels. The probe shows a remarkable specificity towards Fe3+ and Hg2+ ions through "naked-eye" detection as well as via ratiometric fluorescence emission with limits of detection of 9.75x10(-8) M and 39x10(-8) M for Fe3+ and Hg2+ ions, respectively. Further, shifts in the voltammogram towards anodic potential of Delta E-1/2= 31 and 33 mV are observed upon binding Fe3+ and Hg2+ ions, respectively. Characterization of compound 4 has been done by H-1 NMR, C-13 NMR, high-resolution mass spectrometry (HRMS) and CHN analysis studies. The stoichiometry of the complex of the present probe with either Fe3+ or Hg2+ is indicative of a 1:1 ratio, which was determined by Job's plot as well as H-1 NMR titration data. The incorporation of compound 4 in solid support has made the work more practicable. In addition, the practical application of receptor 4 was successfully explored towards the detection of Fe3+ and Hg2+ ions in real water samples by using the different water sources.