A schiff base ligand of coumarin derivative as an ICT-Based fluorescence chemosensor for Al3+

We have developed a novel coumarin-based chemosensor H2L with ICT character bearing the hydra zone of substituted phenol, synthesized by the condensation of 2-hydroxy-4-methylbenzohydrazide with 3-acetylcoumarin. The fluorescence spectra of the receptor H2L demonstrated that the sensor could selectively recognize Al3+ over other metal ions and the detection limit was found in the micromolar concentration range. Sensing capability of the receptor for Al3+ was reversible. Cu2+ complex of H2L was structurally characterized which gave the basis for possible structure of Al3+ complex of H2L. The Turn On fluorescence of H2L is based on intramolecular charge transfer (ICT), chelation enhanced fluorescence (CHEF) and C=N isomerization to serve as fluorescent chemosensor in DMF-water solvent mixture. The receptor H2L showed a remarkably red-shifted absorption spectrum in the presence of Al3+ in DMF. B3LYP-SCRF/6-31G* density functional theory explains the ICT mechanism. (C) 2016 Elsevier B.V. All rights reserved.