A nonsymmetric salamo-based turn-off fluorescent probe for the detection of Cu 2+and its structurally rare dinuclear Cu(II) complex

A salamo-based fluorescent probe H2LS was synthesized by grafting 3-tert-butyl-5-bromosalicylaldehyde and 2-hydroxy-1-naphthaldehyde onto 1, 2-bis(aminooxy)ethane. The probe can selectively and sensitively recognize Cu2+ ions, accompanied by a significant fluorescence quenching change from blue fluorescence to no fluorescence, and the probe can rapidly respond to Cu2+ ions in a short time. Meanwhile, there is a linear relationship between the fluorescence intensity at 393 nm and the concentration of Cu2+ ions (0.05-10 mM). Therefore, the probe can realize the quantitative detection of Cu2+ ions in aqueous solutions with a low detection limit of 4.64 x 10(-7) M. In addition, X-ray structure analysis of the Cu(II) complex of H2LS showed that one of the two oxime-oxygen atoms of the probe (L-S)(2-) unit is involved in the coordination with Cu(II) atom. The density functional theory (DFT) was validated to further confirm the recognition mechanism of the probe H2LS to Cu2+ ions. (c) 2022 Elsevier B.V. All rights reserved.

Automated summary

A salamo-based fluorescent probe H2LS has been developed for the selective and sensitive recognition of Cu2+ ions, allowing quantitative detection in aqueous solutions.