Quantification of Site-Specific Cation Exchange in Metal-Organic Frameworks Using Multi-Wavelength Anomalous X-ray Dispersion

Journal Article · Mon Sep 23 00:00:00 EDT 2013 · Chemistry of Materials

DOI:https://doi.org/10.1021/cm400858d· OSTI ID:1092599

Brozek, Carl K.; Cozzolino, Anthony F.; Teat, Simon J.; Chen, Yu-Sheng; Dinc,; Mircea, ^[1]

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1. MIT

We employed multiwavelength anomalous X-ray dispersion to determine the relative cation occupation at two crystallographically distinct metal sites in Fe²⁺-, Cu²⁺-, and Zn²⁺-exchanged versions of the microporous metal–organic framework (MOF) known as MnMnBTT (BTT = 1,3,5-benzenetristetrazolate). By exploiting the dispersive differences between Mn, Fe, Cu, and Zn, the extent and location of cation exchange were determined from single crystal X-ray diffraction data sets collected near the K edges of Mn²⁺ and of the substituting metal, and at a wavelength remote from either edge as a reference. Comparing the anomalous dispersion between these measurements indicated that the extent of Mn²⁺ replacement depends on the identity of the substituting metal. We contrasted two unique methods to analyze this data with a conventional approach and evaluated their limitations with emphasis on the general application of this method to other heterometallic MOFs, where site-specific metal identification is fundamental to tuning catalytic and physical properties.

• Research Organization: Argonne National Lab. (ANL), Argonne, IL (United States). Advanced Photon Source (APS)
• Sponsoring Organization: DOE - BASIC ENERGY SCIENCES
• OSTI ID: 1092599
• Journal Information: Chemistry of Materials, Vol. 25, Issue (15) ; 08, 2013; ISSN 0897-4756
• Publisher: American Chemical Society (ACS)
• Country of Publication: United States
• Language: ENGLISH