Metal-linker bonds serve as the "glue" that binds metal ions to multitopic organic ligands in the porous materials known as metal-organic frameworks (MOFs). Despite ample evidence of bond lability in molecular and polymeric coordination compounds, the metal-linker bonds of MOFs were long assumed to be rigid and static. Given the importance of ligand fields in determining the behaviour of metal species, labile bonding in MOFs would help explain outstanding questions about MOF behaviour, while providing a design tool for controlling dynamic and stimuli-responsive optoelectronic, magnetic, catalytic, and mechanical phenomena. Here, we present emerging evidence that MOF metal-linker bonds exist in dynamic equilibria between weakly and tightly bond conformations, and that these equilibria respond to guest-host chemistry, drive phase change behavior, and exhibit size-dependence in MOF nanoparticles.
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http://dx.doi.org/10.1039/d3dt04164f | DOI Listing |
Acc Mater Res
October 2024
Department of Chemistry, University of Manchester, Manchester, M13 9PL, U.K.
Since the advent of the Haber-Bosch process in 1910, the global demand for ammonia (NH) has surged, driven by its applications in agriculture, pharmaceuticals, and energy. Current methods of NH storage, including high-pressure storage and transportation, present significant challenges due to their corrosive and toxic nature. Consequently, research has turned towards metal-organic framework (MOF) materials as potential candidates for NH storage due to their potential high adsorption capacities and structural tunability.
View Article and Find Full Text PDFJ Am Chem Soc
August 2024
Department of Chemistry and Biochemistry, Material Science Institute, University of Oregon, Eugene, Oregon 97403, United States.
Size reduction offers a synthetic route to tunable phase change behavior. Preparing materials as nanoparticles causes drastic modulations to critical temperatures (), hysteresis widths, and the "sharpness" of first-order versus second-order phase transitions. A microscopic picture of the chemistry underlying this size dependence in phenomena ranging from melting to superconductivity remains debated.
View Article and Find Full Text PDFDalton Trans
January 2024
Department of Chemistry and Biochemistry, Material Science Institute, University of Oregon, Eugene, OR 97403, USA.
Metal-linker bonds serve as the "glue" that binds metal ions to multitopic organic ligands in the porous materials known as metal-organic frameworks (MOFs). Despite ample evidence of bond lability in molecular and polymeric coordination compounds, the metal-linker bonds of MOFs were long assumed to be rigid and static. Given the importance of ligand fields in determining the behaviour of metal species, labile bonding in MOFs would help explain outstanding questions about MOF behaviour, while providing a design tool for controlling dynamic and stimuli-responsive optoelectronic, magnetic, catalytic, and mechanical phenomena.
View Article and Find Full Text PDFNano Lett
February 2023
Department of Chemistry and Biochemistry, Material Science Institute, University of Oregon, Eugene, Oregon97403, United States.
Conventional semiconductor nanocrystals exhibit wide-ranging optical behavior, whereas the size-dependent photophysical properties of metal-organic framework (MOF) nanocrystals remain an open research frontier. Here, we present size- and temperature-dependent optical absorption spectra of common MOFs with particle sizes ranging from tens of nanometers to several micrometers. All materials exhibit optical gaps that decrease at elevated temperatures, which we attribute to the dynamic nature of MOF metal-linker bonds.
View Article and Find Full Text PDFChem Commun (Camb)
January 2023
Department of Chemistry and Biochemistry, Material Science Institute, University of Oregon, Eugene, OR 97403, USA.
We report "flexibility constants"-a conceptual analog to metal-ligand stability constants-of UiO-66, the prototypical "stable" MOF, across a wide temperature range in both vacuum and in the presence of typical guest solvents. With these data, we extract key thermodynamic parameters governing the reversible bond equilibrium and demonstrate that guest molecules strongly favor the reversible dissociation of MOF metal-linker bonds.
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