Triphenylamine-Based Colorimetric and Fluorometric Sensor for Cu²⁺, Co²⁺ Ions and Volatile Acid Vapour: Experimental...

In this work, we describe the development of an imidazole functionalised colorimetric receptor (TDC) that can distinguish Cu²⁺ and Co²⁺ ions in aqueous acetonitrile medium with colour changes that are visible to the naked eye. With the addition of small amount of Cu²⁺ the colour changes from colourless to Persian green and for Co²⁺ it changes to light violet. Additionally, TDC exhibits exceptional sensitivity to Cu²⁺ and Co²⁺ cations in aqueous acetonitrile by fluorometric change, acting as a "turn-off" luminous chemosensor. Lower detection limits of 21.5 nM and 24.2 nM were used to validate fluorometric selectivity towards Cu²⁺ and Co²⁺ ions. It was evident that with passing the vapours of TFA the colour of the chemosensor TDC changes from colourless to mild green with the emergence of new peak at 638 nm. In order to examine the interaction site, determine the energies of the border molecular orbitals, and validate some of the experimental findings, a computational DFT research was conducted on the free ligand TDC and complex with Cu²⁺ and Co²⁺. The sensing ability of TDC was also supported by the silica based portable, easily disposable device studies.