New stable cobalt-based compound as multifunctional fluorescent probe for highly sensitive detection of 2,4,6-trinitrophenol and Fe³⁺ in water environment

A novel luminescent compound with formula [Co(tpt)(HTMA)]·H₂O (1) (tpt = 2,4,6-tris(4-pyridyl)-1,3,5-triazine, HTMA = trimellitic acid) with three-dimensional structure was synthesized via hydrothermal method. Compound 1 with good thermal and chemical stability as fluorescent probe exhibits high sensitivity and selectivity for detecting 2,4,6-trinitrophenol (TNP) and Fe³⁺ in water environment through fluorescence quenching, in which the Ksv is up to 1.236 × 10⁵ M⁻¹ for TNP and 1.138 × 10⁴ M^-1 for Fe³⁺, and detection limit of TNP and Fe³⁺ were 2.165 × 10^-6 M and 7.18 × 10^-6 M, respectively. Furthermore, the quenching mechanisms were elucidated through the powder X-ray diffraction (PXRD) analysis, the UV/Vis absorption spectra and the density functional theory calculations, demonstrating the synergistic effect of photoelectron transfer and competitive light absorption for TNP, and competitive light absorption effect for Fe³⁺. This work shows potential applications of coordination compound based fluorescent sensor for sensitive detection of multiple trace contaminants in water environment.