A novel "on-off-on" acylhydrazone-based fluorescent chemosensor for ultrasensitive detection of Pd2+

A novel acylhydrazone-based fluorescent sensor G has been successfully synthesized to achieve ultrasensitive detection of Pd2+ in water. Compound G is composed of gallic acid derivatives and biphenyl by acylhydrazone group, which formed a suspension and promote intermolecular self-assembly in DMF by pi-pi stacking, van der Waals forces and intermolecular hydrogen bonds, leading to the formation of stable supramolecular organogels OG in DMF by the gel factor G. And the supramolecular organogels OG realized ultra-sensitive detection of Pd2+ in water via fluorescence quenching at 475 nm. The LOD for Pd2+ for the chemosensor G is 2.03 x 10(-8) M and the resulting metal gel PdG can also recognize H2OP4- among the various anions by fluorescence spectroscopy. And the sensing mechanism of chemosensor G and metal ions has been studied through a series of characterization methods including FE-SEM, FT-IR, XRD, H-1 NMR titrations and XPS, with the results indicating that the pi-pi stacking and hydrogen bond were broken during the addition of the cation. (C) 2020 Elsevier B.V. All rights reserved.