Test kit of chromogenic and ratiometric 1,10-phenanthroline based chemosensor for the recognition of F- and CN- ions

A simple, novel colorimetric and absorption ratiometric chemosensor 1 based on 1, 10-phenanthroline and naphthalene platforms has been synthesized and demonstrated. The photophysical response of chemosensor 1 was investigated by colorimetric, UV-vis and H-1 NMR titration method. 1 behaved as colorimetric sensor for F- and CN- and exhibited naked eye-detectable color changes based on hydrogen bonding interactions followed by deprotonation. Moreover, 1 displayed an absorption ratiometric response for both F- and CN- ions (1:1 complex) in the recognition event. The recognition mechanism has been supported by DFT computational calculations and H-1 NMR studies. Significantly, the detection limits of chemosensor 1 towards F- and CN- have been evaluated to be 2.8 x 10(-7) M and 5.8 x 10(-7) M, which are lower than the maximum values of F- (1.5 mg/L) and CN- (1.9 mu M) ions permitted by WHO. Chemosensor 1 can be conveniently and effectively used as test kit for sensing of fluoride and cyanide ions in the solid state without any additional equipment. The color change was more intense for F- ions in comparison to CN- ions both in the solution and solid state which well corroborated to the higher binding constant and lower limit of detection value of F- ion.