SENSORS

Identification of chemical species is always an indispensable part and goal of chemical research. In recent times, the detection of toxic ionic species is finding significant attention owing to their relevance to human health. In general, colorimetric and fluorescent sensors find significant interest in this regard due to their easy operational procedures. Especially in India, contamination of toxic ionic species in water sources is a huge concern wing to their detrimental effects on human health. In southern parts of India, contamination of fluoride ions has drawn considerable attention. For the past few years, in our research group, we have been engaged in understanding fluoride ions' chemistry and developing fluorescent molecules that can specifically recognize fluoride ions without any interference from other anions. Conventional fluorescent sensors for fluoride ions often utilize hydrogen bonding interactions. However, such weak interactions can lead to very little selectivity or specificity. We have been interested in the developments of triarylborane (TAB) based luminescent sensors in this regard. TAB based molecules can reversibly bind to fluoride anions via Lewis acid-base adduct formations often accompanied with observable changes of their optical properties. [1-10] However, they also experience interference from small anions like cyanide, which often complicates the recognition process. In our trials, we have successfully developed fluoride selective sensors and Lab-on-a-molecule systems that can effectively distinguish fluoride and cyanide anions via different optical channel processes. [5-6] Apart from this, we have also successfully developed far-red and NIR sensors based on TAB moieties. [8]