Luminescent hollow micro- and nanocrystals have been successfully obtained taking advantage of the self-assembly behavior and the aggregation-induced emission enhancement properties of several bispyrazolate Pt(II) metallomesogens decorated with four terminal alkyl chains. Oil-in-water droplets have been used to confine the Pt(II) compounds and drive them to be self-assembled via intermolecular Pt···Pt interactions into spherical aggregates of about 200 or 50 nm. Evaporation of the oil phase generates highly-stable aqueous dispersions of nanocrystals that emit a bright orange light as a result of the existence of ³MMLCT excited states. Different methods and conditions have been tested for studying the effect of several parameters such as the temperature and the stirring speed in the final particle size and in the polydispersity index. Moreover, the micro- and nanocrystals are able to entrap hydrophobic drugs between the alkyl chains of the compounds, forming stable dispersions of drug-loaded capsules in water. The droplet method is applied in the area of metallomesogens for the first time to synthesize self-assembled Pt(II) nanocapsules, which opens a new field of study that could allow the use of these liquid crystal materials in biomedical applications.

The application of novel methodologies to the synthesis of nanomaterials is still a challenge in many different technological and scientific fields. New efficient and reproducible synthetic methodologies, that produce fewer residues and reduce the cost of raw materials must be developed. In the present work, we have explored the attractive possibility to apply the cheap iron (Ⅱ) sulphate salt in the reduction process of the K₂PtCl₄ to produce colloids suspensions. The synthesis took places in water and was assisted by sodium citrate (SC) using polyvinylpyrrolidone (PVP) as a surfactant. The adjustment of this novelty process allows obtaining well-dispersed and sub-20 nm dendrimer-type platinum nanoparticles (Pt D-NPs). The nano-dendrimers produced have been characterized using dynamic light scattering (DLS), transmission electron microscopy (TEM), high-resolution TEM (HR-TEM), XRD spectroscopy, inductive couple plasma (ICP) analysis, Fourier transform infrared (FT-IR) and ultraviolet–visible (UV–vis) spectroscopy. Interesting conformational results derived from the size and shape will be discussed. Catalytic application of the Pt D-NPs has been explored in the reduction of p-nitrophenol (p-NP) to p-aminophenol (p-AP) in aqueous media at room temperature obtained TOF value of 253 min^-1. Finally, our Pt D-NPs were tested as artificial metalloenzyme showing catechol oxidase activity for oxidation of L-DOPA.