Colorimetric Chemosensor for Sulfide Anion Detection Based on Symmetrical Nitrovanillin Azine

Abstract

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 5-nitrovanillin (NV) then the NV was condensed with hydrazine hydrate to produce the NA. 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 × 10−5 M 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 and quantitatively analysis of sulfide anion in tap water.

Novel benzothiazole–pyrazoline–styrene hybrid for ultrasensitive detection of Hg(II) ions: Synthesis and chemosensor evaluation

“…By contrast, compound 3b attained considerably lower LoD and LoQ of 8.94 and 29.79 nM, respectively. These values are substantially lower compared with those observed in research conducted with a LoD range of 200 nm to 1430 nm [11][12][13][14]. These data reveal the notable sensitivity enhancement of Hg(II) detection due to the extended conjugation system in the presence of styrene moiety.…”

“…The complexation between chemosensor agents with Hg(II) ion causes changes in their optical properties [10]. Hundreds of chemosensor agents have been designed and evaluated; however, they suffer from difficulty and costly preparation and low sensitivity for real sample measurements at 200 to 1430 nm [11][12][13][14][15].…”