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Updated: Jun 23, 2026
08:43
Molten-Salt Synthesis of Complex Metal Oxide Nanoparticles
Published on: October 27, 2018
Three lanthanum MOF polymorphs: insights into kinetically and thermodynamically controlled phases
Felipe Gándara1, Víctor A de la Peña-O'Shea, Francesc Illas
1Instituto de Ciencia de Materiales de Madrid, CSIC, Madrid, Spain.
Inorganic Chemistry
|April 21, 2009
Summary
Researchers synthesized RPF-4 polymeric frameworks, discovering three unique crystal structures with novel topologies. DFT calculations revealed the commonly formed polymorph is metastable, challenging previous assumptions about thermodynamic stability.
Area of Science:
- Materials Science
- Crystallography
- Chemistry
Background:
- Rare-earth-based polymeric frameworks (RPFs) are advanced materials with tunable properties.
- The ligand 4,4'-(hexafluoroisopropylisopropylidene)bis(benzoic acid) is versatile for constructing RPFs.
- Polymorphism in RPFs can significantly impact their functional characteristics.
Purpose of the Study:
- To synthesize and characterize RPF-4 polymeric frameworks.
- To investigate the structural diversity and topological properties of RPF-4 polymorphs.
- To determine the relative thermodynamic stability of the observed polymorphs using DFT calculations.
Main Methods:
- Synthesis of RPF-4 frameworks using rare-earth elements and a specific benzoic acid ligand.
- X-ray diffraction analysis to determine the crystal structures of obtained polymorphs.
- Density Functional Theory (DFT) calculations to compute relative energies of polymorphs.
Main Results:
- Successfully synthesized RPF-4, yielding up to three distinct polymorphs.
- The three polymorphs exhibit unusual, uninodal, penta-coordinated network topologies.
- Two of the identified topologies are novel, with one designated hxg-d-5-Imma.
- DFT analysis indicates the frequently obtained polymorph is metastable, contrary to expectations.
Conclusions:
- RPF-4 frameworks exhibit significant structural diversity with novel topologies.
- The common synthetic outcome for RPF-4 is a metastable phase.
- Thermodynamic stability of RPF polymorphs requires careful consideration beyond simple formation frequency.
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