Flexible eightfold interpenetrating diamondoid network generating 1D channels: selective binding with organic guests

Area of Science:

• Coordination Chemistry
• Materials Science
• Supramolecular Chemistry

Background:

• Metal-organic frameworks (MOFs) are crystalline materials constructed from metal ions and organic linkers.
• Interpenetrating networks offer unique structural and functional properties due to their complex topologies.
• Diamondoid networks represent a specific class of highly symmetric and robust framework structures.

Purpose of the Study:

• To synthesize and characterize a novel 8-fold interpenetrating diamondoid network based on a Ni(II)cyclam complex.
• To investigate the structural features, including the interpenetration mode and channel dimensions.
• To explore the dynamic and guest-binding properties of the synthesized framework.

Main Methods:

• Self-assembly of a Ni(II)cyclam macrocyclic complex and sodium tetrakis[4-(carboxyphenyl)-oxamethyl]methane.
• Crystallographic analysis to determine the network topology and structure.
• Sorption/desorption experiments to study guest molecule interactions and framework flexibility.

Main Results:

• An 8-fold interpenetrating diamondoid network, [Ni(cyclam)]2[TCM]·2DMF·10H2O, was successfully synthesized.
• The network exhibits an unusual [4 + 4] interpenetration mode, creating 1D channels (6.7 Å x 4.7 Å).
• The framework demonstrates flexibility, becoming nonporous upon guest removal and regaining porosity upon re-immersion in a DMF/water mixture.

Conclusions:

• The synthesized material represents a new example of a flexible, interpenetrating diamondoid network.
• The dynamic nature of the framework allows for reversible structural changes and guest uptake.
• The desolvated host exhibits selective binding affinities for different guest molecules like alcohols and pyridine.