Reactive & Functional Polymers, Vol.123, 26-33, 2018
Quinone based oligomeric sensors as colorimetric probes for cyanide anion: Effects of solvent medium and substituent on sensing
The main objective of the present study is to understand the structure-property relationships of sensor capable of colorimetric response, upon the addition of particular anions, due to hydrogen-bonding association between sensor and anion. Further, hydrogen-bonding association between sensor and anion, and thereby colorimetric response of the receptor in various solvent media was also targeted. For this, we have synthesized chloro-substituted quinone based oligomer sensor (QO-Cl) and cyano-substituted quinone based oligomer sensor (QO-CN), which contain the thiourea as a binding site. These oligomeric sensors were exploited as colorimetric sensors for cyanide anion [CN-]. Further, the sensing abilities of these sensors for CN- recognition in various solvents were monitored to investigate the influence of solvent on the hydrogen bonding association between sensor and anion. Our colorimetric and spectrometric results unveiled that the QO-CN sensor has shown the better binding constant (K-QO-CN(CN)- - = 39,317 M-1) and detection of limit (DOL = 1.2 mu M) for CN- than that of QO-Cl, (KQO-Cl-CN - = 1950 M-1; DOL = 69 mu M). This can be attributed to the higher electron withdrawing nature of -C N than the moderately electron-withdrawing substituent Cl.