Coordination chemistry under confined conditions: a simplified illustrative view

Spherical-shaped polyoxomolybdate structures can be synthesized/designed so that they behave as an artificial cell/nano-chromatograph (AC/NC) towards a wide range of (counter-)cations, e.g., ammonium, sodium, rubidium, caesium, calcium, cadmium, nickel, cerium and praseodymium. After formal identification of eight related basic molecular processes, their interplay is categorized tentatively with reference to three parameters: the structure of the respective molecular holes/pores exposed to the solution, the size/ionic radii of the (counter-)cations of the AC/NC, and the lability of the cations’ water hydration shell. It is proposed that there is the option to use the AC/NCs to study, e.g., the complexation behaviour of cations under confined conditions with the possibility to mimic cation transport through biological ion channels, but also to get general information about transport processes through molecular pores. The intrinsic properties of the AC/NCs, which can be even synthesized on a (kilo)gram scale, are also thought to open a new era in the study of water structures that may be formed at the nanometre scale in the presence or absence of electrolytes. .