Dual Fluorimetric Sensor for Tandem Detection of Cadmium and Cysteine: An Approach for Designing a Molecular Keypad Lock System

A fluorimetric sensor for dual and sensitive detection of Cd²⁺ ion and Cysteine (based on 2-picolylamine platform) was developed.The sensor was designed and synthesized by simple condensation method and characterized by using common spectroscopic methods. The observations made from the kinetics of absorption and emission profile shows that probe Pdac behaves as ‘‘ON–OFF’’ fluorescent quenching sensor for cadmium ions. The probe exhibit selectivity in fluorescence quenching behaviour over other competitive metal ions, and also the Pdac-Cd²⁺ ensemble behave as an efficient ‘‘OFF–ON’’ type sensor for an essential amino acid Cysteine. Moreover, this dual sensing nature of the sensor makes it successfully applied for the designing of a molecular keypad lock system.