Preparation of Zn-based MOFs photoluminescent coatings on cotton fabrics and their application in anti-counterfeiting

In this paper, a series of new photoluminescent coatings on cotton fabrics were prepared by integrating Zn-based MOFs (ZnBDC), and ZnBDC was encapsulated with luminescent guests (Eu³⁺ and crystal violet (CV)). The results showed that a large amount of ZnBDC nanomaterials could effectively grow on cotton fabric, and the encapsulation of luminescent guests did not damage their structural integrity and morphology. The emission spectra of different encapsulated samples exhibited different fluorescence under excitation at 321 nm. Notably, different from the single Eu³⁺ emission observed in single Eu³⁺-encapsulated ZnBDC cotton fabric, the emission intensity of Eu³⁺ in dual (Eu³⁺ and CV) encapsulated sample changed significantly at different bands, and it dominated by an unusual ⁵D₀ → ⁷F₄ transition (693 nm). The transformation of a specific symmetric site of Eu³⁺ is responsible for this unusual emission. Moreover, the fluorescence color of encapsulated samples could be coded by regulating the concentration of encapsulated CV according to the special features of Eu³⁺ photoluminescence. Therefore, photoluminescent cotton fabrics have a potential application in the anti-counterfeiting of textiles.