Non-monotonic lattice expansion in zeolitic imidazolate frameworks during heating

Area of Science:

• Materials Science
• Chemistry
• Crystallography

Background:

• Zeolitic imidazolate frameworks (ZIFs) are a class of metal-organic frameworks (MOFs) with diverse applications.
• Understanding the thermal expansion behavior of ZIFs is crucial for their practical use.
• ZIF-62, a prominent MOF, exhibits unique structural properties.

Purpose of the Study:

• To investigate the impact of linker modification on the thermal expansion of ZIF-62.
• To explore the relationship between structural integrity and thermal expansion behavior.
• To characterize the anisotropic thermal expansion of ZIF-62 and its derivative.

Main Methods:

• High-energy in situ X-ray diffraction was employed to study ZIF-62 and its derivative.
• The study involved substituting conventional benzimidazolate linkers with those containing two additional methyl groups.
• Variable temperature measurements were conducted to analyze thermal expansion.

Main Results:

• The incorporation of methyl groups into the linkers resulted in increased structural integrity of ZIF-62.
• Variable anisotropic thermal expansion was observed in both the original ZIF-62 and the modified material.
• The methyl groups influenced the framework's response to temperature changes.

Conclusions:

• Linker modification with methyl groups enhances the structural robustness of ZIF-62.
• The study reveals a tunable anisotropic thermal expansion in ZIF-62 derivatives.
• These findings contribute to the design of MOFs with tailored thermal properties.