Negative area compressibility in silver(I) tricyanomethanide

Area of Science:

• Materials Science
• Solid-State Chemistry
• Crystallography

Background:

• Molecular frameworks are crystalline materials with tunable properties.
• Compressibility is a key mechanical characteristic of materials.
• Negative compressibility, where a material expands under compression, is rare and highly sought after.

Purpose of the Study:

• To investigate the mechanical behavior of the Ag(tcm) molecular framework under hydrostatic pressure.
• To characterize the structural changes responsible for any observed compressibility anomalies.
• To explore the potential of negative area compressibility in novel materials.

Main Methods:

• Single-crystal X-ray diffraction was used to monitor structural changes.
• Hydrostatic pressure was applied using a diamond anvil cell.
• Lattice parameters and structural models were analyzed under varying pressures.

Main Results:

• The Ag(tcm) framework displays negative area compressibility, expanding in two orthogonal directions under hydrostatic compression.
• This unusual behavior is attributed to the flattening of honeycomb-like layers.
• A rapid pressure-driven collapse of interlayer separation drives the observed expansion.

Conclusions:

• Ag(tcm) represents the first reported molecular framework exhibiting negative area compressibility.
• The mechanism involves a unique pressure-induced structural rearrangement of its layered architecture.
• This discovery opens new avenues for designing materials with exotic mechanical responses.