Highly Sensitive and Selective Sulfite Ion Sensor Based on Biochemically Stable Iodo‐Functionalized Coumarin Fluorophores

Belonging to the class of sulfur oxyanions, the physiologically prevalent sulfite (SO32−) species has been serving as a popular synthetic additive to enhance the shelf life of a plethora of foods and beverages like bread and wine. On the contrary, an impermissible endogenous accumulation of this reactive sulfur species via multiple factors has been concerned in the functioning of skin disorders and neurodegenerative diseases like Alzheimer's. Accordingly, a pivotal role of sulfite in food quality and human health warrants a reliable analytical technique for the rapid and sensitive detection of SO32− ions in environmental specimens. This article features a new‐fangled iodo‐functionalized coumarin molecule (D), followed by an exploration of its analytical utility as a selectively sensitive sensor for SO32− ions via “switch‐on” fluorescence. In stark contrast to its poorly ion‐discriminating iodine‐free analogue (E) as reported in the literature, the new fluorophore D was capable of rapidly sniffing out sulfite ions (∼3 min) in a specific range of 1000–1 μM, in the back‐drop of a diverse array of environmentally relevant anions at an ultra‐low concentration of 77 nM in semi‐aqueous medium by using simple and cheap fluorescence spectroscopy. The formed sensor found highly selective and sensitive in presence of wide variety of interfering ions and biothiols, which suggest their extreme utilization in the real samples. According to best of our knowledge, it is the first report, which can detection sulfite ion at very low concentration level and it work efficiently under UV‐illumination with bright fluorescence. A comparable sensitivity of D towards the target analyte (SO32− ions) was also recorded in real samples i. e. fresh real water samples and fresh juice specimens. The present paper involves sensitive and selective sulfite‐sensing through chemodosimeter D. The molecule D demonstrates a selectively sensitive and rapid detection of substantially low doses of sulfite ions (0.077 μM) in semi‐aqueous medium via switch‐over fluorescence, particularly in the close proximity of competitively interfering sulfur oxyanions and biological thiols. An equally effective fluorometric sensing potential of D towards the target analyte (SO32−) in sulfite‐spiked real water samples and diverse fresh juice specimens has been posted in this report.