An asymmetric salamo-type fluorescent chemosensor for efficient recognition of Cu2+ and B4O72ˉ ions

A novel salamo-type fluorescent probe NBS (5-(N,N′-diethylamino)-2,2′-[ethylenedioxybis(nitrilomethylidyne)]phenolnaphthol) for selectively recognition of Cu2+ and B4O72ˉ was successfully synthesized. According to the Cu2+ recognition experiment, the probe NBS underwent a coordination process with Cu2+, leading to fluorescence quenching. Theoretical analysis of the recognition mechanism was conducted through DFT calculations. The binding ratio of NBS to Cu2+ was further determined to be 1:1 through high-resolution mass spectrometry. The limit of detection (LOD) of NBS for Cu2+ was calculated to be 3.57 × 10−8 M, and the association constant (Ka) was 5.45 × 104 M−1. In addition, the probe NBS can also be used for selective detection of B4O72ˉ, which was theoretically analyzed through molecular electrostatic potential. The limit of detection (LOD) of NBS for B4O72ˉ was calculated to be 7.13 × 10−8 M, and the association constant was 5.66 × 104 M−1. At the same time, the probe can also quantitatively detect Cu2+ in water samples.