Tailored synthesis of iron oxide nanoparticles for specific applications using a statistical experimental design.

For this work, iron oxide nanoparticles are synthesized by the co-precipitation method with stoichiometric amounts of Fe2+ and Fe3+ salts in a 1:2 ratio in distilled water and the pH is raised by adding an aqueous ammonia solution by controlled dripping. Nanoparticles precipitating after the reaction time are magnetically filtered and stored in ethanol for further analysis. Superparamagnetic Fe3O4 nanoparticles with a slight deviation from the stoichiometry are obtained, with sizes between 7.4 and 12.8 nm and saturation magnetization between 40 and 78 emu/gr. At pH 6, rod-shaped nanoparticles are obtained in addition to spherical ones. With a statistical design, it is shown how the morphological, structural and magnetic properties of the resulting nanoparticles can be manipulated by the synthesis parameters, offering many possibilities to tailor the materials to a wide range of applications.

Ionic liquid mixtures as energy storage materials: a preliminary and comparative study based on thermal storage density.

Fifteen equimolar binary mixtures are synthesized and thermophysically evaluated in this study. These mixtures are derived from six ionic liquids (ILs) based on methylimidazolium and 2,3-dimethylimidazolium cations with butyl chains. The objective is to compare and elucidate the impact of small structural changes on the thermal properties. The preliminary results are compared to previously obtained results with mixtures containing longer eight-carbon chains. The study demonstrates that certain mixtures exhibit an increase in their heat capacity. Additionally, due to their higher densities, these mixtures achieve a thermal storage density equivalent to that of mixtures with longer chains. Moreover, their thermal storage density surpasses that of some conventional materials commonly used for energy storage.

Divergent Synthesis of Porous Tetraphenylmethane Dendrimers.

Tetraphenylmethane-ethynylene-based shape-persistent dendrimers are a new class of nanoobjects with an intriguing 3D architecture. We report an efficient divergent strategy for their synthesis based on the Sonogashira Pd-catalyzed coupling of terminal alkynes with aryl iodides. As repeat unit, we prepared a tetraphenylmethane derivative bearing a terminal alkyne and three triazene moieties. Coupling of this building block to tetrakis(p-iodophenyl)methane afforded, after triazene activation, a dodecaiodo-terminated first generation dendrimer, which was transformed by another Sonogashira coupling into a methoxy-terminated second generation dendrimer with persistent globular shape and well-defined cavities. This work also unveils new aspects of triazene chemistry, i.e., the unprecedented efficient generation of an azo compound by mixing of a triazene with phenol.