My technical talks often include a slide that shows several kinds of atomically precise components that may prove useful in composite nanosystems. One image is labeled “polyoxometalates”, a name that isn’t widely known. I think it should be.
Polyoxometalates (POMs) are molecular structures that are, in effect, atomically precise bits of metal oxide that contain from a few to a few hundred metal atoms, and polyoxotungstates and molybdates are among the most versatile. What are they good for?
- Ionic conductivity
- Catalytic oxidation
- Photochromic response
- Single-molecule magnetism
- Photochemical catalysis
- Anti-retroviral activity
- Hosts for guest-host chemistry
- Potential molecular electronic devices
- Building blocks for larger structures
- Starting points for covalent modification
And more, of course.
POMs can contain other elements, and are diverse in form, composition, and function. They’re in the same size range as proteins, but stiffer, more regular, and with a very different spectrum of potential functions.
POMs can form in water, at ordinary temperatures, under conditions compatible with biomolecular systems. Indeed, some bind to proteins with enough specificity to make them of pharmaceutical interest. Some proteins serve as templates for POM formation, and one of these has been mapped in atomic detail. It templates and contains several distinct POM structures simultaneously, some of which don’t form without it.
All this suggests that POMs are of great interest as nanocomponents, including functional components for modular molecular nanosystems that exploit DNA frameworks and peptide foldamers (a.k.a. proteins). Beyond this, they are examples of the kinds of inorganic structures that (when design tools become good enough) can be made with atomic precision through growth processes directed by self-assembled biomolecular templates.
De-Liang Long and Leroy Cronin have written a review, “Towards Polyoxometalate-Integrated Nanosystems” [pdf], which provides a good starting point for those interested in learning more. The review closes by saying that
…recent advances in polyoxometalate chemistry [list of references here] mean that all the components are available conceptually and synthetically to allow the design and realisation of polyoxometalate-based integrated nanosystems.
Whether as a basis for integrated nanosystems or as an important class of components, POMs may come to play a large role in upcoming developments.
- Modular Molecular Composite Nanosystems
- Templates for atomically precise metal-oxide nanostructures
- Toward Advanced Nanotechnology: Nanomaterials (2)
- Self-Assembly for Nanotechnology