Zeolitic imidazolate frameworks as an efficient platform for potential curcumin-based on/off fluorescent chemosensor

Incorporating the fluorescent organic compound on the platform toward the capture of metal ions has become an attractive strategy for chemical sensor. Curcumin-based sensory platforms are fabricated chemo-sensors for the detection of cations and anions. Herein, the homogenous nanoparticle porous zeolitic imidazolate frameworks, ZIF-8 and ZIF-11 with a smaller than 100 nm particle size were used as platform for curcumin loading. The ZIF compounds were characterized by powder X-ray diffraction, N2 sorption isotherms, and thermal gravimetric analysis to assess their potential for liquid adsorption. According to investigation of liquid adsorption, the curcumin concentration, time, and temperature of adsorption process have been carried out to provide the adsorption properties and adsorption capacity of two materials. The maximum adsorption capacity on both ZIFs was up to 4.5 mg mg−1, with faster adsorption rates than other adsorbents reported. Compared to ZIF-11, ZIF-8 surprisingly demonstrates higher encapsulation, intraparticle diffusion, and lower kinetic parameters of k2. This phenomenon is explained via the crystallographic aperture size, surface area, and affinity of the 2-methylimidazolate linker in ZIF-8 relative to the benzimidazole linker in ZIF-11. The release of curcumin in both pH 5.5 and 7.4 environments below 2% for 24h showed the consistent stability of curcumin in the nanocarrier. In addition, the curcumin-based sensory ZIF-8 and ZIF-11 exhibited efficient fluoride ion sensing performance with a detection limit as low as 100 ppm. The colorimetric fluorescence sensing at ON/OFF mode highlighted the promising potential of Cur-based ZIF materials for the high dose of fluoride ion in water at pH 5.5 and 7.4.