Neutral red as Novel and Highly Selective Chemosensor for Detection and Determination of Cyanide in Aqueous Media

Anions play important role in chemical, biological and environmental processes. An important aspect of modern chemistry is the utilization of hydrogen bonding in the development of receptors for recognition of anions [۱]. Among various anions, cyanide is one of the most concerned anions because it is highly toxic and harmful to human health since cyanide binds to the ferric form of cytochrome-c and inhibits the mitochondrial electron-transport chain [۲]. There are several limitations associated with many of currently available cyanide sensors: such as (i) These sensors work only in organic solvents; (ii) They have poor selectivity over fluoride or acetate; (iii) They show low sensitivity; and (iv) They possess short-wavelength absorption or emission [۳]. Anion receptors are that reported rather difficult to synthesize or require expensive instruments for detections. Taking this dilemma into consideration recently, we have undertaken an extensive research program to explore bromopyrogallol red as an easily available dye demonstrated a high chromogenic receptor for cations and anions [۴]. In this work, we disclose a new approach toward this goal. Neutral red (NR) actualized the novel and simple chemosensor for cyanide concept in water media. The binding sites of the receptor are directly attached to binding of anions could be monitored by changes in the photophysical properties of the receptor by UV–Vis spectroscopy and naked-eye detection. Neutral red has been identified as highly sensitive probe for CNˉ which responds at ۰.۲ μmol L-۱ concentration levels among other competing anions through a fast response time of less than ۴۰ s which is much lower than most recently reported chromogenic probes. This method could have potential application in a variety of cases requiring rapid and accurate analysis of CNˉ for human serum and water samples.