Spontaneous formation of autocatalytic sets with self-replicating inorganic metal oxide clusters.

Miras, Haralampos N; Mathis, Cole; Xuan, Weimin; Long, De-Liang; Pow, Robert; Cronin, Leroy · Proc Natl Acad Sci U S A · 2020

basic_science · Level V

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Abstract

Here we show how a simple inorganic salt can spontaneously form autocatalytic sets of replicating inorganic molecules that work via molecular recognition based on the {PMo<sub>12</sub>} ≡ [PMo<sub>12</sub>O<sub>40</sub>]<sup>3-</sup> Keggin ion, and {Mo<sub>36</sub>} ≡ [H<sub>3</sub>Mo<sub>57</sub>M<sub>6</sub>(NO)<sub>6</sub>O<sub>183</sub>(H<sub>2</sub>O)<sub>18</sub>]<sup>22-</sup> cluster. These small clusters are able to catalyze their own formation via an autocatalytic network, which subsequently template the assembly of gigantic molybdenum-blue wheel {Mo<sub>154</sub>} ≡ [Mo<sub>154</sub>O<sub>462</sub>H<sub>14</sub>(H<sub>2</sub>O)<sub>70</sub>]<sup>14-</sup>, {Mo<sub>132</sub>} ≡ [Mo<sup>VI</sup><sub>72</sub>Mo<sup>V</sup><sub>60</sub>O<sub>372</sub>(CH<sub>3</sub>COO)<sub>30</sub>(H<sub>2</sub>O)<sub>72</sub>]<sup>42-</sup> ball-shaped species containing 154 and 132 molybdenum atoms, and a {PMo<sub>12</sub>}⊂{Mo<sub>124</sub>Ce<sub>4</sub>} ≡ [H<sub>16</sub>Mo<sup>VI</sup><sub>100</sub>Mo<sup>V</sup><sub>24</sub>Ce<sub>4</sub>O<sub>376</sub>(H<sub>2</sub>O)<sub>56</sub> (PMo<sup>VI</sup><sub>10</sub>Mo<sup>V</sup><sub>2</sub>O<sub>40</sub>)(C<sub>6</sub>H<sub>12</sub>N<sub>2</sub>O<sub>4</sub>S<sub>2</sub>)<sub>4</sub>]<sup>5-</sup> nanostructure. Kinetic investigations revealed key traits of autocatalytic systems including molecular recognition and kinetic saturation. A stochastic model confirms the presence of an autocatalytic network involving molecular recognition and assembly processes, where the larger clusters are the only products stabilized by the cycle, isolated due to a critical transition in the network.