Harnessing Structural Dynamics in a 2D Manganese-Benzoquinoid Framework to Dramatically Accelerate Metal Transport in Diffusion-Limited Metal Exchange Reactions

Lujia Liu, Liang Li, Jordan A. Degayner, Peter H. Winegar, Yu Fang, T. David Harris*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

20 Scopus citations

Abstract

Postsynthetic metal exchange represents a powerful synthetic method to generate metal-organic frameworks (MOFs) that are not accessible through direct synthesis, yet it is often hampered by slow reaction kinetics and incomplete exchange. While studies of metal exchange reactions have primarily focused on the transmetalation process, transport of exogenous metal ions into the framework structure represents a critical yet underexplored process. Here, we employ X-ray crystallography, electron microscopy, and energy dispersive X-ray spectroscopy to comprehensively examine the transport of Co2+ and Zn2+ ions during postsynthetic metal exchange reactions within the 2D manganese-benzoquinoid framework (Et4N)2[Mn2L3] (H2L = 3,6-dichloro-2,5-dihydroxy-1,4-benzoquinone). These studies reveal that exogenous metal ions diffuse primarily through the 1D channel along the crystallographic c axis, and this transport represents the rate-determining step. In addition, the Mn framework exhibits reversible dynamic structure behavior, contracting upon desolvation and then rapidly restoring its original structure and full volume upon resolvation. When conducting metal exchange reactions using a partially desolvated sample, these structural dynamics lead to acceleration of metal transport by up to 2000-fold, improve product purity, and give exchange of a larger fraction of metal sites. Finally, upon performing metal exchange using full-solvated crystals, an intermediate product can be isolated that constitutes a unique example of a 2D material with a gradient vertical heterostructure.

Original languageEnglish (US)
Pages (from-to)11444-11453
Number of pages10
JournalJournal of the American Chemical Society
Volume140
Issue number36
DOIs
StatePublished - Sep 12 2018

ASJC Scopus subject areas

  • Catalysis
  • Chemistry(all)
  • Biochemistry
  • Colloid and Surface Chemistry

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