Metal–Organic Framework-Coated Photonic Crystals for High-Performance Thin-Layer Chromatography

Traditional SiO2 gel-based thin-layer chromatography (TLC) is unable to separate substances with close structures, and its detection requires dyeing when the sample has neither fluorescence nor ultraviolet (UV) absorption signals. Here, high-performance TLC was developed based on metal–organic framework-coated photonic crystal (MOF/PC) films. Using the MIL-100/PC as the TLC plate, the cresol isomers can now be separated in a 2 cm development distance due to the enhanced adsorption–desorption and the good selectivity from the micropores. Meanwhile, the cresol changes the refractive index of MOF/PC, which produces color changes for sample recognition. Compared to the traditional TLC, the MOF/PC TLC shows much higher selectivity toward the analytes, which fully compensates its limited plate numbers and ensures a high-resolution separation. It also provides a convenient solution for chemical analysis as the detection based on structural color change does not require UV irradiation or dyeing treatment.