The combination of the two luminous substances to prepare a multifunctional gel film brings the unexpected pH response properties in the pH range of sweat. Weakly acidic sweat can induce a decrease in the red fluorescence of MOF in the composite gel film, forcing the blue fluorescence of BDCZ to highlight, resulting in a red-blue transformation of the functional gel film visible to the naked eye. Besides sweat can promote the phosphorescence of DBCZ. Based on these, a dual-mode sweat pH sensor and sweat-based anti-counterfeiting can be designed (Figure 1b).
Properties of Y-TCPP/DBCZ PVA composite film
According to the previous reports, the fluorescence intensity of Y-TCPP MOF increases with the increase of pH from 6-12.[27] Although these properties are still maintained in the composite film, there have no responsive photoluminescent property in the pH range of sweat. Actually, this excellent alkali stimulation responsive luminescence performance of MOF provides an excellent platform for our composite luminescent materials.