Highly selective and sensitive chemosensor for Al(III) based on isoquinoline Schiff base.

As a colorimetric and fluorescent turn-on sensor to Al, N'-(2-hydroxybenzylidene)isoquinoline-3-carbohydrazide (HL) has been easily synthesized. The fluorescence intensity increases by 273 times in the presence of Al at 458 nm. Meanwhile, the experiment data indicate that the limit of detection for Al is 1.11 × 10 M. Remarkably, the blue fluorescence signal of HL-Al could be specially observed by the naked eye under UV light and is significantly different from those of other metal ions. Fluorescence switch based on the control of Al and EDTA proved HL could act as a reversible chemosensor. According to ESI-MS result and the Job's plots, the 2:1 coordination complex formed by HL and Al could be produced. Density functional theory calculations were performed to illustrate the structures of HL and complex. The cell imaging experiment indicates that HL can be applied for monitoring intracellular Al levels in cells.