During recent two decades, there has been a great emergence of interests in the development of fluorescent probes for various metal cations.1e3 On account of their importance in many biological and environmental processes, especially transition metal ions have received an increasing concern.4,5 Heavy metal cations such as Cu2þ, Pb2þ and Zn2þ ions are
widely considered as pollutants as well as the essential trace elements in biological systems.