Dual mode selective chemosensor for copper and fluoride ions: a fluorometric, colorimetric and theoretical investigation.

A pyrene containing chemosensor viz. has been designed for the efficient and selective detection of Cu(2+) and F(-) ions in dual sensing mode which do not interfere with each other. The chemosensing behavior of towards Cu(2+) was demonstrated through fluorescence, time resolved fluorescence spectroscopy, and visual fluorescence colour changes, and towards F(-) through naked-eye colour changes, absorption and (1)H NMR titrations. The chemosensor shows excellent selectivity towards Cu(2+) through an excimer switch-off mechanism. Density Functional Theory (DFT) calculations were performed to show the structure and electronic properties of and its copper complex [-Cu(2+)]. The selectivity and sensitivity towards F(-) were explained in terms of H-bonding interactions between and F(-), then deprotonation of . The biological application of has been evaluated in HEK 293 cells and it exhibits good membrane permeability for the detection of Cu(2+). The sensor also shows appreciable sensitivity towards fluoride in toothpaste.