Metal-Organic Polyhedra as Molecular Nanoparticles

Ultra-small inorganic nanoparticles (i. e. size below 10 nm) are important because they fill the gap between the molecular and the nanoscale regimes.1 On this scale, nanoparticles can merge properties of both regimes, such as solubility in different media with high reactivity and unique physicochemical and pharmacokinetic properties. However, their practical application demands chemical functionalization of their external surface, as it enables their stabilization and protection, tuning of their hydrophilic/hydrophobic character, and introduction of new functional molecules in to them (e.g. to modulate interactions between the nanoparticles and Biosystems). Thus, inorganic ultra-small nanoparticles are inherently polydisperse by virtue of the core or the external functionalization. This limitation makes it impossible to utilize a variety of methods that would provide molecular-level information regarding their composition and structure, which ultimately dictates the performance of the ultra-small nanoparticle.Herein, we propose the use of metal-organic polyhedral molecules (MOPs)2 assembled from metal ions and organic ligands, which size is comprised between 1 – 5 nm, as new nanoscopic platforms or molecular nanioarticles (Figure 1). MOPs present reactive groups of different nature decorating their structure that can be reacted stoichiometrically to functionalize their structure and add new functionalities such as chirality and being soluble in a broad range of solvents. Specifically, we take advantage of the hybrid nature of MOPs to post-synthetically modify their composition through coordination and/or covalent chemistry. This new strategy provides structurally well-defined nanoscopic platforms for delivery, sorption and catalytic applications.