DFT based ESIPT process of luminescent chemosensor: Taft and Catalan solvatochromism

► The quenching of fluorescence was observed in the presence of copper metal ion. ► Formation of the keto-isomer III due to ESIPT. ► Competition of intra and intermolecular hydrogen bonding in binary solvents. ► A multi-component linear regression analysis to correlate UV and emission results. ► PES diagram, MEP and electronic properties studied using Gaussian-03.