Inspired by the spontaneous self-assembly of hollow virus capsids and protein cages found in nature, a family of hollow spherical structure with general formula M_nL_2n can be obtained via the coordination-directed multi-component self-assembly of bent bis(pyridine) ligands and square-planar Pd²⁺ ions. Endo and exo-hedral functionalization of the nanocontainer complexes have been realized by introduction of functional groups into the organic ligands. Due to the nanoconcentrator effect, endo-functionalised spherical complex could be used not only for the template-synthesis of mono-dispersed polymers or nanoparticles, but also for the catalytic transformations of small substrates. Meanwhile, exo-functionalized complexes can selectively recognize a variety of substrates, such as oligonucleotides and DNA. The design principles, synthesis, characterization and functional applications of such nano-container molecules are summarized in this paper.

Contents
1 Introduction
2 Design and synthesis of the nano-containers
3 Functionalization and applications
3.1 Functional cavity
3.2 Functional surface
4 Conclusion and outlook