Modulation of Crystallinity and Optical Properties in Composite Materials Combining Iron Oxide Nanoparticles and Dye-Containing Covalent Organic Frameworks

Abstract

Two series of organic-inorganic composite materials were synthesized through solvothermal imine condensation between diketopyrrolopyrrole dialdehyde <b>DPP-1</b> and 5,10,15,20-tetrakis(4-aminophenyl)porphyrin (<b>TAPP</b>) in the presence of varying amounts of either amino- or carboxylate-functionalized superparamagnetic iron oxide nanoparticles (<b>FeO</b>). Whereas high <b>FeO</b> loading induced cross-linking of the inorganic nanoparticles by amorphous imine polymers, lower <b>FeO</b> content resulted in the formation of crystalline covalent organic framework (COF) domains. All hybrid materials were analyzed by magnetization measurements, powder X-ray diffraction, electron microscopy, IR and UV/Vis absorption spectroscopy. Crystallinity, chromophore stacking and visible absorption features are directly correlated to the mass fraction of the components, thus allowing for a fine-tuning of materials properties.