A unitary fluorescence probe to sense Co2+: Validated by theoretical studies and X-ray crystallography

A new salamo-type fluorescence probe H2L was synthesized by a series of reactions and corroborated by single-crystal X-ray crystallography and 1H NMR spectra. Fluorescence of Co2+ selectively response showed “off” when cations were sequentially detected. The LOD of H2L to Co2+ was calculated to be 3.73 × 10-7 M in DMF/water (9:1, v/v) solution system. Meanwhile, the single crystal of the Co2+ complex with H2L was obtained by solvent evaporation. The structure of the complex [Co3(L)2(MeOH)2(μ-OAc)2]·2MeOH was validated by single-crystal X-ray diffraction, IR, and elemental analyses, and the mechanism of recognition of Co2+ by H2L was got. Density functional theory (DFT) and Hirshfeld surface analyses were investigated to further understand the experimental results observed.