“Naked eye” detection of CN- from aqueous phase and other extracellular matrices: An experimental and theoretical approach mimicking logic gate concept

A napthaldehyde-hydrazine based colourimetric chemosensor (NDNPH)((E)-1-((2-(2,4-dinitrophenyl)hydrazono)methyl)naphthalen-2-ol) has been designed, synthesised and evaluated for target specific anion detection through H-bonding mechanism. The chemosensor exhibited high selectivity towards lethal anion like CN- with 1:1 binding stoichiometry and 1.2 x 107 M-1 binding constant. The sensor NDNPH showed high selectivity towards CN- with a distinct naked eye colour change from light yellow to purple. The detection limit from aqueous phase was calculated to be as low as 1.26 µM which is far below the permissible limit. The sensor NDNPH was equally responsive in different biological matrices such as fresh Bovine serum and human blood plasma. This shows the bioapplicability of the chemosensor which is of immense importance in analytical domains in modern era. In addition to the several spectroscopic studies, the DFT studies along with the Electrostatic potential surface analysis and Loewdin spin population calculation confirmed the binding behaviour of sensor molecule with the targeted analyte. Apart from these, the reversible UV-Vis responses of the synthesized chemosensor NDNPH towards CN- and Cu2+ can mimic several molecular logic functions and hence may be used to fabricate several complex electronic circuitry based on Boolean Algebra. Moreover, “test strips” based on sensor NDNPH were fabricated which may act as a conventional and efficient cyanide detection kit for real-field detection without the help of any additional instruments by the virtue of “Dip-Stick” approach. In a nutshell this simple, cost-effective, azomethine based simple Schiff base molecule detects biologically lethal anion (CN ) in various biological matrices with real field application in analytical as well as in engineering sciences.