Following the light: 3D-printed COF@poly(2-hydroxyethyl methacrylate) dual emissive composite with response to polarity and acidity

A new imine-based covalent organic framework (COF) functionalized in its cavities with moieties of the chromophore Nile Red has been synthesized and characterized. Using mechanical (ultrasonics) and chemical (acid-self-exfoliation) methods, exfoliation of the COF powder has been explored in water and water/organic media. In the latter, the obtained colloids exhibit dual emission originating from the Nile Red units (red) and the COF framework (green) that can be employed to prepare ratiometric sensors of polarity and acidity. Thus, taking advantage of the in situ exfoliation of the material in methacrylic monomers, free-standing polymeric films that preserve the optical properties of the exfoliated COF have been prepared. Finally, 3D liquid crystal display (LCD) additive manufacturing has been employed to prepare the dual emissive composites as tailored 3D-printed objects.