Supramolecular Metal-Based Entities for Biomedical and Biological Applications

In the supramolecular chemistry field, coordination-driven self-assembly has provided the basis for tremendous growth across many sub-disciplines, spanning fundamental investigations regarding the design and synthesis of new architectures to defining different practical applications. Usually, the coordination compounds for this type of chemistry are classified into two main branches: metal-organic frameworks (MOFs) and supramolecular coordination complexes (SCCs). MOFs are metal-organic porous coordination polymers consisting of metal ions or clusters and organic linkers, which are connected by metal–ligand coordination bonds. In turn, SCCs are well-defined, discrete 2D or 3D molecular entities with suitable metal centers undergoing coordination-driven self-assembly with ligands containing multiple binding sites. Through the judicious choice of the coordination geometry of the metal ion precursor and complementary structure of the multidentate ligand, an almost infinite range of SCCs and MOFs can form via the process of self-assembly. Despite numerous synthetic efforts, and a number of inherent favorable properties, the field of supramolecular metal-based entities--either SCCs or MOFs--for biological/biomedical applications is still in its infancy.

In this Research Topic, we aim to present the fundamentals in terms of synthesis and characterization of the host-guest properties of these systems, followed by an overview of the possible biological applications with representative examples. This will be delivered in the form of reviews and full papers as well as short communications. We will therefore give emphasis to discrete 3D and 2D SCCs such as metallacages, capsules, helicates, and macrocycles. We will also prioritize polymeric MOFs, highlighting the state-of-the-art research toward their biological applications--for example as anticancer agents, drug delivery systems, imaging agents, as well as for molecular recognition. As such, systems designed for DNA and protein recognition with potential applications in imaging and therapy will be presented. Overall, we seek to provide the future outlook for this exciting research field, which, in defining the various challenges, will hopefully stimulate new ideas within various scientific communities, including those of bioinorganic, inorganic, organometallic, and medicinal chemistry.