Colorimetric and fluorescent sensing of Al3+ by a new 2-hydroxynaphthalen based Schiff base "Off-On" chemosensor

Abstract

A new 2-hydroxynaphthalen based Schiff base colorimetric and fluorescence chemosensor, H2acid}, for selective sensing of Al3+ ions has been synthesized and characterize by different physico-chemical and spectroscopic techniques. The probe shows enhanced fluorescence and significant color change from bright yellow to colorless in the presence of Al3+ ions in methanol-water (9:1 v/v) solution, without interference from other metal ions. The binding mode of H2L with Al3+ was studied by UV–vis, fluorescence titration, job's plot analysis, and ESI-MS. The probe acts as a bidentate ligand and interacts with Al3+ ions with a binding constant of Kb = 1.546 × 105 M−1. The limit of detection for Al3+ is found to be 6.4 × 10−7 M. The cytotoxicity of the probe has been evaluated by MTT assay on MCF-7 cell line, indicating more than 92% cell viability in the concentration range of 1.25–50 μM with no serious cytotoxicity on cells. Live cell imaging study clearly indicates that the accumulation of Al3+ in living cells can be detected by H2L.