Fluorescent sensor for selective detection of Al3+ based on quinoline–coumarin conjugate

• We have designed a new chemosensor for aluminum ions.
• 2-Methyl quinoline-4-carboxylic hydrazide was rarely synthesized.
• L shows a large fluorescence enhancement with turn-on over 200-fold in ethanol.
• It has lower detection limit.

A fluorescence probe, 8-formyl-7-hydroxyl-4-methyl coumarin – (2′-methylquinoline-4-formyl) hydrazone (L) has been synthesized. The chemosensor is found preferential binding to Al3+ in presence of other competitive ions with associated changes in its optical and fluorescence spectra behavior. Upon addition of Al3+ to a solution of L, it shows 200-fold enhancement of fluorescence intensity which might be attributed to form a 2:1 stoichiometry of the binding mode of LAl(III) and the chelation enhanced fluorescence (CHEF) process at 479 nm in ethanol. The lowest detection limit for Al3+ is determined as 8.2 × 10−7 M.

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