The role of cations in uranyl nanocluster association: A molecular dynamics study

Ken Newcomb, Varinia Bernales, Surya Prakash Tiwari, Laura Gagliardi, Edward J. Maginn

Research output: Contribution to journalArticlepeer-review

Abstract

Actinyl ions can self-assemble in aqueous solution to form closed cage clusters ranging from 1.5 to 4.0 nm in diameter. The self-assembly, stability, and behavior of the nanoclusters depend on the nature of the aqueous environment, such as the pH and cations present. In this work, a classical force field for [(UO2)20(O2)30]20- (U20) peroxide nanoclusters in aqueous solution was developed from quantum-mechanical calculations. Using molecular dynamics simulations, the preferred binding sites of six cations (Li+, Na+, K+, Rb+, Cs+, and Ca2+) to the nanocluster were determined. Replica exchange molecular dynamics was used to equilibrate the structure and determine the equilibrium distribution of cations and water with respect to the nanocluster cage. In addition, the free energy barriers associated with cations entering the cluster were computed. Finally, the association of two cages was investigated by computing the free energy as a function of intercage distance. The free energy profiles reveal that the nanoclusters prefer to be associated when neutralized with divalent cations, but do not associate when neutralized with monovalent cations. This could explain the formation of tertiary structures observed experimentally.

Original languageEnglish (US)
Pages (from-to)1847-1854
Number of pages8
JournalPhysical Chemistry Chemical Physics
Volume22
Issue number4
DOIs
StatePublished - 2020

Bibliographical note

Funding Information:
This work was supported as part of the Materials Science of Actinides Energy Frontier Research Center, funded by the U.S. Department of Energy, Office of Science, Basic Energy Sciences under award DE-SC0001089.

Publisher Copyright:
© 2020 the Owner Societies.

PubMed: MeSH publication types

  • Journal Article

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