Tuning the selectivity of aggregation induced enhanced emission active terepthalohydrazide template via modulating the terminal sensory side chain

Here we report, design and synthesis of two chemosensors based on a terepthalohydrazide template. We want to explore how the change can affect the overall sensing property. To our surprise both the sensors L1 and L2 exhibit Aggregate Induced Enhanced Emission showing capability and analyte recognizing ability. Ligand L1 shows a 14 fold increase in the fluorescence intensity with the addition of selective CN^- ions by hampering the ESIPT phenomenon exhibiting in the ligand. While L2 shows a strong selectivity with Cu²⁺ accompanied by a red shift of 96 nm in the emission spectra. TURN OFF response of L2 towards Cu²⁺ is a result of Chelation Induced Enhanced Quenching (CHEQ). Ligand L1 shows a strong Aggregation active behaviour with bright green fluorescence while L2 shows Aggregation with cyan blue colour fluorescence. The DFT and TDDFT calculations were performed in order to demonstrate the structure of ligand, complexes and its electronic properties.