Linear Dependence of Photoluminescence in Mixed Ln-MOFs for Color Tunability and Barcode Application

Multicolored photoluminescence tuning in a single-phase material has invaluable potential in display and security applications. By deliberate design of a multifunctional antenna ligand and precise control of mixed metal ionic compositions in lanthanide metal-organic frameworks (Ln-MOFs), we achieved dichromatic fine-tuning among red, green, or blue primary colors through growth of a series of isomorphous Ln-MOF crystals·solvents of formula [Ln_nLn′_1-n(TTP)₂·H₂O]Cl₃ (Ln = Ln′ = Eu, Tb, and Gd, 1-3; Ln = Eu, Ln′ = Tb, 4-8; Ln = Gd, Ln′ = Eu, 9-11; Ln = Gd, Ln′ = Tb, 12-14; 0 < n < 1; TTP = 1′,1″-(2,4,6-trimethylbenzene-1,3,5-triyl)tris(methylene)tris(pyridine-4(1H)-one)). The linear dependence of the emissions were analyzed, and the mathematical matrix models were established, which are useful to control the synthetic conditions and to predict the color chromaticity coordinates under varied excitation wavelengths. The potential relevance of these multicolored photoluminescent Ln-MOFs to barcoded materials was demonstrated.