Dual-state emissive carborane-based aza-oxa-triazole macrocycles as probes for nitroaromatic compounds

A series of o-carborane-based aza-oxa-triazole macrocycles (No, D₂, D₄) were synthesized via Cu(I)-catalyzed azide-alkyne cycloaddition (CuAAC). Simply by substituting the azide diethanolamine precursor, two dansyl-modified macrocycles (D₂ and D₄) with dual-state emission (DSE) were readily obtained. The incorporation of the dansyl moiety significantly enhanced the luminescence, resulting in higher quantum yields and longer fluorescence lifetimes. Additionally, the macrocycles exhibit unique aggregation-induced emission (AIE) properties and macrocycles D₂ and D₄ simultaneously exhibit aggregation-induced quenching (ACQ) and AIE characteristics. Furthermore, these macrocycles function as selective fluorescent sensors for nitroaromatic compounds, particularly demonstrating excellent specificity and anti-interference ability toward 2,4,6-trinitrophenol (TNP) with a notable fluorescence quenching response. Macrocycle D₂ achieved a remarkably low detection limit of 7 × 10^-8 M for TNP in THF.