Quick accessible dual mode turn-on red fluorescent chemosensor for Cu(II) and its applicability in live cell imaging

A novel fluorescent chemosensor 9,10-Diphenyl-7H-benzo[d,e]imidazo[2,1-a]isoquinolin-7-one (BIDQ-1), which exhibits rapid colorimetric and fluorimetric response for copper ions over other competitive metal ions under mild conditions has been synthesized easily by a simple one pot condensation method. On addition of Cu(II), BIDQ-1 shows a distinct color change from yellow to green, thus permitting the probe to be used for naked eye detection of Cu(II). The new fluorescent probe exhibits a turn-on fluorescence response towards Cu2+ under physiological conditions with high sensitivity and selectivity. The turn-on fluorescence behaviour of BIDQ-1 with Cu(II) was found to be via an intramolecular charge transfer (ICT) mechanism, by TD-DFT calculations. The probe was found to be applicable for imaging intracellular Cu2+ in living cells.