Nitrogenase employs a sophisticated electron transfer system and a Mo−Fe−S−C cofactor, designated the M‐cluster [(cit)MoFe7S9C]), to reduce atmospheric N2to bioaccessible NH3. Previously, we have shown that the cofactor‐free form of nitrogenase can be repurposed as a protein scaffold for the incorporation of a synthetic Fe−S cluster [Fe6S9(SEt)2]4−. Here, we demonstrate the utility of an asymmetric Mo−Fe−S cluster [Cp*MoFe5S9(SH)]3−as an alternative artificial cofactor upon incorporation into the cofactor‐free nitrogenase scaffold. The resultant semi‐artificial enzyme catalytically reduces C2H2to C2H4, and CN−into short‐chain hydrocarbons, yet it is clearly distinct in activity from its [Fe6S9(SEt)2]4−‐reconstituted counterpart, pointing to the possibility to employ molecular design and cluster synthesis strategies to further develop semi‐artificial or artificial systems with desired catalytic activities.
Inorganic salts usually demonstrate simple phasal behaviors in dilute aqueous solution mainly involving soluble (homogeneous) and insoluble (macrophase separation) scenarios. Herein, we report the discovery of complex phase behavior involving multiple phase transitions of clear solution – macrophase separation – gelation – solution – macrophase separation in the dilute aqueous solutions of a structurally well-defined molecular cluster [Mo7O24]6−macroanions with the continuous addition of Fe3+. No chemical reaction was involved. The transitions are closely related to the strong electrostatic interaction between [Mo7O24]6−and their Fe3+counterions, the counterion-mediated attraction and the consequent charge inversion, leading to the formation of linear/branched supramolecular structures, as confirmed by experimental results and molecular dynamics simulations. The rich phase behavior demonstrated by the inorganic cluster [Mo7O24]6−expands our understanding of nanoscale ions in solution.
more » « less- Award ID(s):
- 1904397
- PAR ID:
- 10413629
- Publisher / Repository:
- Nature Publishing Group
- Date Published:
- Journal Name:
- Nature Communications
- Volume:
- 14
- Issue:
- 1
- ISSN:
- 2041-1723
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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