A 3D-To-2D Phase Transition Mediated by Argentophilic Bond Rearrangements in a Coordination Polymer

Area of Science:

• Materials Science
• Crystallography
• Supramolecular Chemistry

Background:

• Materials under pressure typically maintain or increase structural dimensionality.
• Metallophilic interactions can promote higher structural dimensionality.

Purpose of the Study:

• To investigate the pressure-induced structural transformation of a heterobimetallic coordination polymer.
• To explore the role of argentophilic interactions in pressure-dependent structural changes.

Main Methods:

• Synthesis of the heterobimetallic coordination polymer [Cu2(pa)2][Ag(CN)2]2·2H2O.
• High-pressure X-ray diffraction studies to determine crystal structures at ambient and elevated pressures.
• Spectroscopic analysis to correlate structural changes with electronic properties.

Main Results:

• Ambient pressure phase exhibits a 3D structure with ligand-supported 1D Ag···Ag chains.
• A first-order phase transition to a 2D pillared structure occurs at ~3.55 GPa.
• Pressure induces reconstruction of argentophilic interactions into discrete, ligand-unsupported dimers, accompanied by a color change and band gap collapse.

Conclusions:

• Pressure can effectively reduce the structural dimensionality of coordination supramolecular systems.
• Modifying argentophilic interaction connectivity is a viable strategy for pressure-induced structural transformations.
• The observed 3D to 2D transformation offers insights into pressure-responsive materials.