The center templates the ring
in the Self-Assembly of a
Molecular Oxide Nanowheel”
HN Miras et al., Science,
327:72–74 (2010).
The cover of Science features atomically precise inorganic nanostructures, polyoxometalates (POMs), that form by means of atomically precise templates. The outer rings of these structures contain 150 molybdenum atoms.
POMs are a diverse class of nanoscale metal-oxide structures with characteristics that make them remarkably attractive as potential components for self-assembled composite nanosystems.
These characteristics include:
- Atomically precise structures
- Diverse sizes, shapes, properties, and functions
- Good mechanical stiffness
- Facile aqueous synthesis (see below)
- Biomolecular compatibility
I discussed some of their properties and potential applications in an earlier post, “Polyoxometalate Nanostructures”.
The latest paper from Lee Cronin’s lab points to new strategies for making POMs. The authors first discuss the power of templating strategies in organic synthesis, then observe that
The discovery of a similar templating strategy for the reliable fabrication of 2- to 10-nm molecular nanoparticles would revolutionize the synthesis and applications of molecular materials in the same way that templated synthesis has revolutionized the field of organic macrocyclic synthesis over the past 40 years.
[...]
Our results illustrate how a bottom-up assembly process can be used to rapidly obtain gram quantities of a nanomaterial with well-defined size, shape, and composition.
By “well-defined size, shape, and composition”, they mean atomically precise.
I’d like to see experiments that explore possibilities for synthesizing POMs on protein templates (there’s been work on POM synthesis in protein cavities). I’d expect that screening combinations of proteins and POM-forming solutions would yield new structures, and perhaps show the way to rational engineering of POMs through rational engineering of proteins. This would open another bridge between biomolecular and inorganic nanotechnologies.
Synthesis:
The following solutions prepared in distilled and degassed H2O as follows: Solution A: 60 mL (3 M) solution of Na2MoO4·2H2O; Solution B: 60 mL (5M) HCl; Solution C: 60 mL (0.29 M) of Na2S2O4; Solution D: 250 mL (0.2 M) K2MoO4; Solution E: 250 mL (0.4 M) of HNO3. Solutions A, B and C reacted in the mixing chamber 1 using a flow rate of 4 mL / h. Solutions D and E reacted in the mixing chamber 2 using the same flow rate. The outputs of the mixing chamber 1 and 2 reacted in the mixing chamber 3 giving the desirable product in crystalline form within 24 h and under flow conditions in the collection tank.
[from the online supporting material]
See also:
- Modular Molecular Composite Nanosystems
- Polyoxometalate Nanostructures
- Toward Advanced Nanotechnology: Nanomaterials (2)
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