Targeted design of porous materials without strong, directional interactions

Area of Science:

• Materials Science
• Crystallography
• Supramolecular Chemistry

Background:

• Tetrakis(4-sulfophenylmethane) is a molecule with potential for constructing porous materials.
• The synthesis of tetrakis(4-sulfophenylmethane) can lead to unexpected crystalline phases.
• Understanding crystal formation is key to designing new materials with specific properties.

Purpose of the Study:

• To investigate the formation of a porous molecular crystal (TSCl) during tetrakis(4-sulfophenylmethane) synthesis.
• To rationalize the driving forces and intermolecular interactions governing TSCl formation using Crystal Structure Prediction (CSP).
• To evaluate the gas sorption properties of the novel porous TSCl phase.

Main Methods:

• Synthesis of tetrakis(4-sulfophenylmethane) in dichloromethane and water.
• Crystal Structure Prediction (CSP) for rationalizing crystal formation.
• Gas sorption analysis (CO2, N2, H2, CH4 uptake measurements).
• Computational analysis of intermolecular interactions (hydrogen bonding, dispersion forces).

Main Results:

• A porous molecular crystal (TSCl) was successfully synthesized and characterized.
• CSP accurately predicted the formation of the porous TSCl phase.
• TSCl exhibited permanent porosity with selective CO2 adsorption over other gases (N2, H2, CH4).
• Maximum CO2 uptake of 74 cm3 g-1 at 195 K was recorded.
• Intermolecular assembly of TSCl is driven by a combination of weak hydrogen bonds and strong dispersion interactions.

Conclusions:

• Crystal Structure Prediction is a valuable tool for understanding and guiding the formation of porous crystalline materials, even those driven by less intuitive interactions.
• The discovered TSCl phase demonstrates potential for selective CO2 capture applications.
• This work highlights the utility of CSP in crystal engineering beyond traditional directional interactions.