Stitching 2D polymeric layers into flexible interpenetrated metal-organic frameworks within single crystals

Area of Science:

• Materials Science
• Supramolecular Chemistry
• Crystallography

Background:

• 2D coordination polymers with porous structures are of interest for host-guest chemistry.
• Controlling framework flexibility and interpenetration is a key challenge in materials design.

Purpose of the Study:

• To investigate the diffusion of guest molecules into a 2D coordination polymer.
• To explore the formation of flexible interpenetrated metal-organic frameworks (MOFs).
• To understand the structural transformations induced by guest molecule absorption.

Main Methods:

• Synthesis of a 2D coordination polymer with diethylformamide solvates.
• In-situ diffusion of dipyridyl bridging ligands into the crystal lattice.
• X-ray diffraction analysis to monitor structural changes and crystallinity.

Main Results:

• Dipyridyl ligands successfully diffused into the polymer channels, substituting diethylformamide.
• The absorbed dipyridyls stitched adjacent layers, forming flexible interpenetrated MOFs.
• A solvent exchange from diethylformamide to aqua occurred, minimizing congestion.
• A notable layer slippage was observed, altering the framework architecture while preserving crystallinity.

Conclusions:

• The study demonstrates a novel method for constructing flexible interpenetrated MOFs through guest-induced structural transformation.
• The findings highlight the potential of diffusion and substitution processes in designing dynamic crystalline materials.
• This work offers insights into controlling framework flexibility and interpenetration in coordination polymers.