Tunable Solid-State Multicolor Emission in Substitutional Solid Solutions of Metal-Organic Frameworks

Realization of organic-based substitutional solid solutions will facilitate the preparation of solid-state materials with properties that arise from phenomena only displayed by molecules in solution. We demonstrate that multivariate metal-organic frameworks, MOFs, exhibit organic-based substitutional solid solution behavior by tuning their fluorescence, dictated exclusively by predetermined ratios of multivariate organic links. By combining non-fluorescent links with dilute mixtures of red, green, and blue fluorescent links we prepared zirconia-type MOFs that exhibit features of solution-like fluorescence. Our study found that MOFs with fluorophore link concentration of around 1 %mol exhibit fluorescence with decreased inner filtering demonstrated by changes in spectra profiles, quantum yields, and lifetime dynamics expected for excited state proton transfer emitters. Our findings enabled us to prepare organic-based substitutional solid solutions with tunable chromaticity. These materials emit multicolor and white light with high quantum yields, long shelf life, and superb hydrolytic stability at ambient conditions.