Frustrated organic solids display unexpected gas sorption

Area of Science:

• Materials Science
• Supramolecular Chemistry
• Crystallography

Background:

• Calixarenes are macrocyclic compounds with diverse applications.
• Understanding the crystalline forms and their properties is crucial for material design.
• Traditional gas sorption analysis may not capture the behavior of all active materials.

Purpose of the Study:

• To investigate the crystalline region between nonsorptive solvate and desolvate forms of p-tert-butylcalix[5]arene.
• To characterize the gas sorption properties of this intermediate crystalline form.
• To determine if this form represents a novel class of porous materials.

Main Methods:

• Gas sorption studies were conducted.
• Analysis of crystalline structures was performed.
• Comparison with traditional gas sorption trends was made.

Main Results:

• A distinct crystalline region, termed the 'frustrated form', was identified between solvate and desolvate states.
• This frustrated form exhibits rapid gas sorption capabilities.
• The intermediate form demonstrates porosity, previously unrecognized.

Conclusions:

• The frustrated crystalline form of p-tert-butylcalix[5]arene is porous.
• This material represents a new class of porous materials.
• It expands the understanding of gas sorption in crystalline systems.