A novel chemical probe based on the salamo-Co(II) complex for the highly selective fluorescence detection of tyrosine

A new and rare Salamo-Co(II) complex probe L-Co²⁺ was designed and synthesised. The structure of the [Co₃(L)₂(μ-OAc)₂(MeOH)₂]⋅2H₂O complex was obtained by X-ray diffraction experiments. Three Co(II) atoms are in a line in the complex, and all Co(II) atoms form a 6-coordinated octahedral configuration. The probe L-Co²⁺ selectively recognises tyrosine in DMF/H₂O (8:2, v/v). Upon addition of tyrosine, the fluorescence intensity of L-Co²⁺ was enhanced in a short time. The probe showed high selectivity and sensitivity for tyrosine, detection limit is 4.27 × 10^-8 M. The recognition mechanism of probe L-Co²⁺ for Tyr was inferred by FT-IR spectra, UV spectroscopy, ESI mass spectra and DFT calculations. Finally, due to the simplicity and specificity of the identification process, the probe was also subjected to a test paper experiment and a milk assay.