Relating structural disorder and melting in complex mixed ligand zeolitic imidazolate framework glasses

Area of Science:

• Materials Science
• Chemistry
• Solid-State Chemistry

Background:

• Zeolitic imidazolate frameworks (ZIFs) are a class of metal-organic frameworks known for their diverse structures and tunable properties.
• The transformation of crystalline materials into glasses offers opportunities for new material properties and applications.
• Understanding the relationship between crystalline precursors and resulting glass properties is crucial for materials design.

Purpose of the Study:

• To synthesize and characterize novel zeolitic imidazolate framework glasses (ZIF-glasses).
• To investigate the structure-property relationships, focusing on thermal properties and nanoscale porosity.
• To develop a model explaining the thermal behavior of ZIF-glasses based on their crystalline origins.

Main Methods:

• Synthesis of novel crystalline zeolitic imidazolate frameworks [Zn(Im2-x-ybImxmbImy)] using three organic linkers.
• Formation of ZIF-glasses from the corresponding crystalline structures.
• Analysis of thermal properties, including melting and glass transition temperatures.
• Characterization of nanoscale porosity.
• Application of a probabilistic model to correlate structure and properties.

Main Results:

• Successful formation of ZIF-glasses from novel crystalline ZIFs.
• Demonstrated correlation between chemical composition and thermal properties (melting and glass transition temperatures).
• Established link between nanoscale porosity of the glasses and the structural disorder of their crystalline precursors.
• Validated a probabilistic model for predicting thermal properties based on precursor structure.

Conclusions:

• Zeolitic imidazolate framework glasses can be formed from corresponding crystalline structures.
• The thermal properties and nanoscale porosity of ZIF-glasses are directly influenced by the chemical composition and structural characteristics of their crystalline precursors.
• The developed probabilistic model provides a framework for understanding and predicting the properties of ZIF-glasses, facilitating targeted material design.