Fluorescence signalling of transition metal ions by multi-component systems comprising 4-chloro-1, 8-naphthalimide as fluorophore

Fluorescence of 1a and 1b is 'switched on' by the quenching transition metal ions and the extent of fluorescence enhancement is found to be considerably higher than that expected on the basis of photoinduced intramolecular electron transfer in the systems. The observation has been rationalised taking into account the hydrated nature of the transition metal salts and preferential solvation of the fluorophore by the water molecules