Control of reversible ligand insertion via supramolecular interactions in the solid state

Area of Science:

• Solid-state chemistry
• Supramolecular chemistry
• Coordination chemistry

Background:

• Metal complexes can exhibit dynamic behavior in the solid state.
• Supramolecular interactions, such as hydrogen bonding, significantly influence crystal structures and properties.
• Controlling solid-state reactions through external stimuli is a key challenge.

Purpose of the Study:

• To demonstrate the reversible insertion of ligand molecules into a metal complex's coordination sphere in the solid state.
• To investigate the role of supramolecular hydrogen-bonding interactions in mediating this reversible process.
• To study copper(I) nitrate complexes with thiourea as a model system.

Main Methods:

• Synthesis of copper(I) nitrate-thiourea complexes.
• Crystallographic analysis to determine solid-state structures.
• Variable temperature studies to probe structural changes.
• Spectroscopic methods to confirm ligand insertion/removal.

Main Results:

• Demonstrated reversible insertion and removal of thiourea ligands into the coordination sphere of copper(I) nitrate in the solid state.
• Established a direct correlation between the strength and geometry of supramolecular hydrogen bonds and the ligand insertion process.
• Observed distinct structural phases corresponding to the presence and absence of the inserted ligand.

Conclusions:

• Supramolecular hydrogen bonding is a powerful tool for controlling solid-state guest-host chemistry.
• Reversible ligand insertion in metal complexes can be achieved by manipulating non-covalent interactions.
• This work opens avenues for designing responsive solid-state materials based on coordination complexes.