A novel phthalazine based highly selective chromogenic and fluorogenic chemosensor for Co(2+) in semi-aqueous medium: application in cancer cell imaging.

A new phthalazine based chemosensor was developed for the highly selective and sensitive detection of Co(2+) in the mixed solvent system, CH3CN-H2O (1 : 1, v/v). In the presence of Co(2+), the colour of the solution changed from yellow to green; the absorption maxima of was red-shifted from 383 nm to 435 nm, and the fluorescence of at 550 nm was significantly enhanced. The sensor showed a detection limit down to 25 nM by forming a complex species with Co(2+) in 1 : 1 stoichiometry. Furthermore, by means of confocal laser scanning microscopy experiments, it has demonstrated that it can be used as a fluorescent probe for monitoring Co(2+) in living cells.