Multi-signalling cation sensing behaviour of a bis(pyridin-2-yl methyl)aniline based hetarylazo dye

•Cation sensing of hetarylazo dye based upon visual, absorption and electrochemical changes is described.•Sensing mechanism is based upon perturbation in intramolecular charge-transfer upon interaction with cations.•Sensing protocol is supported by 1H NMR studies as well as theoretical calculations.•Hetarylazo dye acts as a multichannel sensor.•Response of the dye towards various cations has also been explored in acidic pH window.

We investigated the cation sensing behaviour of a bis(pyridin-2-yl methyl)aniline appended hetarylazo dye via chromogenic and electrochemical transduction channels. The binding pocket constituting both the pyridyl as well as aniline nitrogen atoms acts as recognition site for the cations and consequent perturbation in the intramolecular charge-transfer prevailing in the dye results in the chromogenic response manifested in the form of hypsochromic shift in the intramolecular charge-transfer band and the attendant naked-eye color changes. The dye exhibits significant changes in its electrochemical behaviour in the presence of cations. The experimental results are also rationalized by time-dependent density functional theory (TD-DFT) calculations.

Graphical abstractThe chromogenic and electrochemical behaviour of bis(pyridine-2-yl methyl)aniline based hetarylazo dye gets perturbed in the presence of cations, most effective being Cu2+. The conversion of ICT to ICT/MLCT is witnessed by TD-DFT calculations.Figure optionsDownload full-size imageDownload as PowerPoint slide