Colorimetric chemosensor for sulfide anion detection based on symmetrical nitrovanillin azine

The nitrovanillin azine (NA) has been successfully synthesized and examined as a colorimetric chemosensor for sulfide anion detection. The NA was synthesized using two steps reaction. Vanillin was reacted with concentrated nitric acid to form 5nitrovanillin (NV) then the NV was condensed with hydrazine hydrate to produce theNA. The NA was obtained and fully elucidated by FTIR, 1H-NMR, 13C-NMR, and GC-MS spectrometer. The NA activity for anionic chemosensor was then carried out on several anions such as F⁻, Cl ⁻, Br⁻, I ⁻, S2⁻, CN ⁻, HCO3 ⁻, AcO ⁻, H2PO4 ⁻, N3 ⁻, NO2 ⁻, SCN ⁻, ClO3 ⁻, and NO3 ⁻. The chemosensor tests showed NA was only selective for S2−in DMF:HEPES buffer (9:1, v/v, 10 mM, pH = 7.4) giving color change from light yellow to dark green. The LOD value was 1.43 × 10−5M and the interaction model of NA-S2−indicated deprotonation mode between the -OH group with sulfide anion in a ratio of 1:1. The NA chemosensor can be applied for qualitatively analysis of sulfide anion using filter paper strips andquantitatively analysis of sulfide anion in tap water.