Hydrogen-bond-modulated negative linear compressibility in a V-shaped molecular crystal

Area of Science:

• Materials Science
• Crystallography
• Computational Chemistry

Background:

• Negative linear compressibility (NLC) materials expand along one dimension when compressed.
• These materials are promising for applications like actuators, switches, and sensors.
• Understanding NLC mechanisms is key to designing novel functional materials.

Purpose of the Study:

• To investigate the "hidden" NLC in the V-shaped molecular crystal bis(5-amino-1,2,4-triazol-3-yl)methane (BATZM).
• To elucidate the role of intermolecular interactions in governing the material's compressive behavior.
• To provide a design strategy for future NLC materials.

Main Methods:

• Density functional theory (DFT) calculations were employed.
• The study focused on the crystal structure and mechanical response of BATZM under hydrostatic pressure.

Main Results:

• DFT calculations revealed NLC in BATZM above 3 GPa, where the crystal expands along the b-axis.
• The crystal initially compresses (0-3 GPa) by compressing hydrogen bonds and flattening molecules.
• Intermolecular hydrogen bonds act as tunable springs and struts, controlling compressibility.

Conclusions:

• BATZM exhibits hidden NLC, driven by the unique behavior of its intermolecular hydrogen bonds under pressure.
• The findings demonstrate a viable strategy for designing new NLC materials by rationally utilizing hydrogen bonds.
• This research contributes to the fundamental understanding and application of materials with unusual mechanical properties.