An eugenol-sulfonyl based fluorescent probe for recognition of Al3+ in real sample analysis and biological application

Abstract

The present work describes an eugenol-sulfonyl based fluorescence chemosensor, H₄L [H₄L=6,6′-((1E,1′E)-((sulfonylbis(6-hydroxy-3,1- phenylene))bis(azanylylidene))bis(methanylylidene))bis(4-allyl-2-methoxyphenol)], which shows maximum emission intensity towards Al³⁺ ion in presence of other competing metal ions. Upon excitation at 440 nm H₄L exhibits a significant rise in fluorescence at 547 nm upon gradual addition of Al³⁺ ion in the HEPES buffer at pH=7.4 (MeOH:H₂O, 4:1, (v/v)). The increasing value of fluorescence is mainly due to chelation enhanced fluorescence effect (CHEF). Complete characterization of the probe (H₄L) and metal bound complex (1) have been determined using a range of methods including UV–Vis absorption titration, fluorescence titration, NMR, ESI-mass, etc. Thus 1:2 binding stoichiometry between H₄L and metal ion has been also proved. Another important aspect: regeneration and reversibility of H₄L are investigated in presence of Na₂EDTA. H₄L exhibits ∼ 10⁻⁶ M order detection limit and significant binding constant (∼10⁶ M⁻¹) for the Al³⁺ ion, suggesting its potential use in bio-imaging studies. The probe was effectively used in real samples as well as paper strip to locate the Al³⁺ ion.