Naked-eye colorimetric cyanide detection by monocarbonyl analogue of curcumin

Abstract

The sensing properties of a monocarbonyl analogue of curcumin (C1-MAC) for cyanide recognition were investigated by UV-Vis absorption spectroscopy. C1-MAC was designed as an alternative of curcumin, since it has similar properties, but does not suffer from its well-known disadvantages, such as tedious preparation from toxic and expensive starting materials and structural instability. C1-MAC exhibited excellent selectivity for cyanide ion over other anions including NO3−, NO2−, Cl−, Br−, H2PO4−, and even over alkaline anions such as SO42−, CH3COO−, F− and HCO3−. The detection mechanism was confirmed by 1H nuclear magnetic resonance experiments, Job's method of continuous variation and the comparative study of the O-methyl protected analogue. The response of the probe to cyanide was easily observed by naked eye with immediate color change of the C1-MAC solution from yellow to deep red. In addition, the application of the probe on fabricated test strips was examined. The test papers demonstrated excellent selectivity towards CN− without significant response from interfering ions such as CH3COO−, F− and HCO3−, showing that this technique is valuable for the convenient detection of cyanide in 100% water samples.