NMR-Enhanced Crystallography Aids Open Metal-Organic Framework Discovery Using Solvent-Free Accelerated Aging

10.26434/chemrxiv.8281787 ◽

2019 ◽

Author(s):

Christopher A. O’Keefe ◽

Cristina Mottillo ◽

László Fábián ◽

Tomislav Friscic ◽

Robert W. Schurko

Keyword(s):

Solid State Nmr ◽

Metal Organic Framework ◽

Accelerated Aging ◽

Solvent Free ◽

X Ray Diffraction ◽

X Ray ◽

Metal Organic ◽

It Application ◽

Organic Framework

NMR-enhanced crystallography enables the characterization of a novel cadmium-based, open metal-organic framework (MOF) from a solvent-free "accelerated aging" process. Whereas accelerated aging was devised as a clean, mild route for making MOFs, these results highlight how it application in materials discovery and characterization is aided by a combination of X-ray diffraction and solid-state NMR spectroscopy.

Download Full-text

Crystallographic Characterization of the Metal–Organic Framework Fe2(bdp)3 upon Reductive Cation Insertion*

10.26434/chemrxiv.12501842 ◽

2020 ◽

Cited By ~ 1

Author(s):

Naomi Biggins ◽

Michael Ziebel ◽

Miguel Gonzalez ◽

Jeffrey R. Long

Keyword(s):

Single Crystal ◽

Single Crystals ◽

Metal Organic Framework ◽

X Ray Diffraction ◽

X Ray ◽

Π Interactions ◽

Cation Framework ◽

Metal Organic ◽

Organic Framework

<div>Precisely locating extra-framework cations in anionic metal–organic framework compounds remains a long-standing, yet crucial, challenge for elucidating structure-performance relationships in functional materials. Single-crystal X-ray diffraction is one of the most powerful approaches for this task, but single crystals of frameworks often degrade when subjected to post-synthetic metalation or reduction. Here, we demonstrate the growth of sizable single crystals of the robust metal–organic framework Fe2(bdp)3 (bdp2− = benzene-1,4-dipyrazolate) and employ single-crystal-to-single-crystal chemical reductions to access the solvated framework materials A2Fe2(bdp)3∙yTHF (A = Li+, Na+, K+). X-ray diffraction analysis of the sodium and potassium congeners reveals that the cations are located near the center of the triangular framework channels and are stabilized by weak cation–π interactions with the framework ligands. Freeze-drying with benzene enables isolation of activated single crystals of Na0.5Fe2(bdp)3 and Li2Fe2(bdp)3 and the first structural characterization of activated metal–organic frameworks wherein extra-framework alkali metal cations are also structurally located. Comparison of the solvated and activated sodium-containing structures reveals that the cation positions differ in the two materials, likely due to cation migration that occurs upon solvent removal to maximize stabilizing cation–π interactions. Hydrogen adsorption data indicate that these cation-framework interactions are sufficient to diminish the effective cationic charge, leading to little or no enhancement in gas uptake relative to Fe2(bdp)3. In contrast, Mg0.85Fe2(bdp)3 exhibits enhanced H2 affinity and capacity over the non-reduced parent material. This observation shows that increasing the charge density of the pore-residing cation serves to compensate for charge dampening effects resulting from cation–framework interactions and thereby promotes stronger cation–H2 interactions.</div>

Download Full-text

Crystallographic Characterization of the Metal–Organic Framework Fe2(bdp)3 upon Reductive Cation Insertion*

10.26434/chemrxiv.12501842.v1 ◽

2020 ◽

Author(s):

Naomi Biggins ◽

Michael Ziebel ◽

Miguel Gonzalez ◽

Jeffrey R. Long

Keyword(s):

Single Crystal ◽

Single Crystals ◽

Metal Organic Framework ◽

X Ray Diffraction ◽

X Ray ◽

Π Interactions ◽

Cation Framework ◽

Metal Organic ◽

Organic Framework

<div>Precisely locating extra-framework cations in anionic metal–organic framework compounds remains a long-standing, yet crucial, challenge for elucidating structure-performance relationships in functional materials. Single-crystal X-ray diffraction is one of the most powerful approaches for this task, but single crystals of frameworks often degrade when subjected to post-synthetic metalation or reduction. Here, we demonstrate the growth of sizable single crystals of the robust metal–organic framework Fe2(bdp)3 (bdp2− = benzene-1,4-dipyrazolate) and employ single-crystal-to-single-crystal chemical reductions to access the solvated framework materials A2Fe2(bdp)3∙yTHF (A = Li+, Na+, K+). X-ray diffraction analysis of the sodium and potassium congeners reveals that the cations are located near the center of the triangular framework channels and are stabilized by weak cation–π interactions with the framework ligands. Freeze-drying with benzene enables isolation of activated single crystals of Na0.5Fe2(bdp)3 and Li2Fe2(bdp)3 and the first structural characterization of activated metal–organic frameworks wherein extra-framework alkali metal cations are also structurally located. Comparison of the solvated and activated sodium-containing structures reveals that the cation positions differ in the two materials, likely due to cation migration that occurs upon solvent removal to maximize stabilizing cation–π interactions. Hydrogen adsorption data indicate that these cation-framework interactions are sufficient to diminish the effective cationic charge, leading to little or no enhancement in gas uptake relative to Fe2(bdp)3. In contrast, Mg0.85Fe2(bdp)3 exhibits enhanced H2 affinity and capacity over the non-reduced parent material. This observation shows that increasing the charge density of the pore-residing cation serves to compensate for charge dampening effects resulting from cation–framework interactions and thereby promotes stronger cation–H2 interactions.</div>

Download Full-text

Crystallographic characterization of the metal–organic framework Fe2(bdp)3 upon reductive cation insertion

Chemical Science ◽

10.1039/d0sc03383a ◽

2020 ◽

Vol 11 (34) ◽

pp. 9173-9180 ◽

Cited By ~ 1

Author(s):

Naomi Biggins ◽

Michael E. Ziebel ◽

Miguel I. Gonzalez ◽

Jeffrey R. Long

Keyword(s):

Single Crystal ◽

Gas Adsorption ◽

Metal Organic Framework ◽

Metal Organic Frameworks ◽

Adsorption Properties ◽

X Ray Diffraction ◽

X Ray ◽

Metal Organic ◽

Organic Framework

Single-crystal X-ray diffraction reveals structural influences on gas adsorption properties in anionic metal–organic frameworks.

Download Full-text

Direct structure elucidation by powder X-ray diffraction of a metal–organic framework material prepared by solvent-free grinding

Chemical Communications ◽

10.1039/c0cc02635b ◽

2010 ◽

Vol 46 (40) ◽

pp. 7572 ◽

Cited By ~ 80

Author(s):

Kotaro Fujii ◽

Ana Lazuen Garay ◽

Janeen Hill ◽

Elena Sbircea ◽

Zhigang Pan ◽

...

Keyword(s):

Structure Elucidation ◽

Metal Organic Framework ◽

Solvent Free ◽

X Ray Diffraction ◽

X Ray ◽

Metal Organic ◽

Organic Framework

Download Full-text

Structural characterization of framework–gas interactions in the metal–organic framework Co2(dobdc) by in situ single-crystal X-ray diffraction

Chemical Science ◽

10.1039/c7sc00449d ◽

2017 ◽

Vol 8 (6) ◽

pp. 4387-4398 ◽

Cited By ~ 45

Author(s):

Miguel I. Gonzalez ◽

Jarad A. Mason ◽

Eric D. Bloch ◽

Simon J. Teat ◽

Kevin J. Gagnon ◽

...

Keyword(s):

Single Crystal ◽

Structural Characterization ◽

Metal Organic Framework ◽

X Ray Diffraction ◽

X Ray ◽

Metal Organic ◽

Gas Interactions ◽

Organic Framework

In situ single-crystal X-ray diffraction experiments enable the direct observation of weak metal–gas interactions in a metal–organic framework.

Download Full-text

Characterization of a Holmium 4,4′-Biphenyldicarboxylate Metal-Organic Framework and Its Potential as a Holmium Carrier System

Journal of Nanoscience and Nanotechnology ◽

10.1166/jnn.2020.17476 ◽

2020 ◽

Vol 20 (5) ◽

pp. 3019-3024 ◽

Cited By ~ 1

Author(s):

Juan P. Vizuet ◽

Abigail L. Lewis ◽

Gregory T. McCandless ◽

Kenneth J. Balkus

Keyword(s):

Metal Organic Framework ◽

X Ray Diffraction ◽

X Ray ◽

Metal Organic ◽

Solvent Molecules ◽

The Stability ◽

Adsorption Desorption ◽

Organic Linker ◽

Organic Framework

There is growing interest in Holmium carriers for radiotherapeutic applications. In this work, a holmium-based metal-organic framework (MOF) using the 4,4′-biphenyldicarboxylic acid (H2BPDC) linker was synthesized and characterized to explore its potential as a radiotherapeutic carrier. The 3D MOF [Ho(BPDC)2]·(CH3)2NH2 was characterized by single crystal X-ray diffraction, FTIR, TGA and PXRD. A challenge to overcome in lanthanide-based MOFs is the deformation or collapse of the framework that can occur after evacuation of the pores. This structure displays high thermal stability and no collapse was observed when the molecules confined in the pores were removed. The coordination around the holmium center (CN = 8) is the key to this stability since only the organic linker and no solvent molecules coordinate to the metallic center. The porosity of the material was confirmed by high-pressure carbon dioxide (CO2) adsorption–desorption analysis. The stability of the MOF, its holmium content (28 wt%) and its porosity are features that make this material a potential holmium carrier for radiotherapeutic applications.

Download Full-text

Synthesis and Structure of a Clathrated Two-Dimensional Metal-Organic Framework: [Cd(4,4'-bpy)2(H2O)2](ClO4)2·(L)2·H2O (L = Bis(1-pyrazinylethylidene)hydrazine)

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc20080024 ◽

2008 ◽

Vol 73 (1) ◽

pp. 24-31

Author(s):

Dayu Wu ◽

Genhua Wu ◽

Wei Huang ◽

Zhuqing Wang

Keyword(s):

Metal Organic Framework ◽

Channel Structure ◽

Two Dimensional ◽

X Ray Diffraction ◽

Guest Molecules ◽

X Ray ◽

Square Planar ◽

Metal Organic ◽

Aqueous Meoh ◽

Organic Framework

The compound [Cd(4,4'-bpy)2(H2O)2](ClO4)2·(L)2 was obtained by the reaction of Cd(ClO4)2, bis(1-pyrazinylethylidene)hydrazine (L) and 4,4'-bipyridine in aqueous MeOH. Single-crystal X-ray diffraction has revealed its two-dimensional metal-organic framework. The 2-D layers superpose on each other, giving a channel structure. The square planar grids consist of two pairs of shared edges with Cd(II) ion and a 4,4'-bipyridine molecule each vertex and side, respectively. The square cavity has a dimension of 11.817 × 11.781 Å. Two guest molecules of bis(1-pyrazinylethylidene)hydrazine are clathrated in every hydrophobic host cavity, being further stabilized by π-π stacking and hydrogen bonding. The results suggest that the hydrazine molecules present in the network serve as structure-directing templates in the formation of crystal structures.

Download Full-text