Solvophobicity-directed assembly of microporous molecular crystals

Area of Science:

• Materials Science
• Crystallography
• Supramolecular Chemistry

Background:

• Organic molecules in the solid state typically exhibit dense packing.
• Conventional porous crystals rely on reticular networks for porosity.
• A new approach is needed to create porous materials from discrete molecules.

Purpose of the Study:

• To develop a solvophobicity-based methodology for assembling discrete molecules into porous forms.
• To synthesize isostructural porous polymorphs of an amphiphilic aromatic molecule, Py₆Mes.
• To investigate the role of solvent dispersion interactions in directing crystal packing and porosity.

Main Methods:

• Solvophobicity-based molecular assembly.
• Synthesis of porous polymorphs of Py₆Mes.
• Computational analysis of crystal structures and intermolecular interactions (dispersion forces).

Main Results:

• Successfully synthesized isostructural porous polymorphs of Py₆Mes.
• Dispersion interactions drive columnar stacking of Py₆Mes, forming nanopores.
• Porous packing is favored in weak dispersion solvents (solvophobic effect); non-porous crystals form in strong dispersion solvents (solvophilic effect).

Conclusions:

• Solvophobicity is a key factor in directing the formation of porous molecular crystals.
• The methodology allows for the rational design of porous materials by controlling solvent properties.
• This approach is applicable to other amphiphilic aromatic molecules, as shown with Py₆Mes analogues.