Macrocyclic Arenes-Based Conjugated Macrocycle Polymers for Highly Selective CO₂ Capture and Iodine Adsorption

Area of Science:

• Materials Science
• Polymer Chemistry
• Supramolecular Chemistry

Background:

• Conjugated macrocycle polymers (CMPs) offer tunable properties for gas uptake and pollutant adsorption.
• Synthetic macrocycles with specific structures and conformations are key to designing advanced CMPs.

Purpose of the Study:

• To synthesize novel CMPs incorporating unique macrocyclic units for enhanced gas adsorption and separation.
• To investigate the iodine (I2) capture capabilities and carbon dioxide (CO2) selectivity of the newly designed CMPs.

Main Methods:

• Pd-catalyzed Sonogashira-Hagihara cross-coupling reaction was employed for CMP synthesis.
• Four CMPs (CMP-1 to CMP-4) were constructed using per-triflate functionalized leaning tower[6]arene (LT6-OTf) and [2]biphenyl-extended pillar[6]arene (BpP6-OTf).
• Gas uptake capacities and separation efficiencies were evaluated under various conditions.

Main Results:

• CMP-4 exhibited a high iodine uptake capacity of 208 wt% in vapor and 94% removal efficiency in aqueous solutions, attributed to its cavity size and aromatic framework.
• CMP-2, derived from BpP6-OTf, demonstrated specific carbon dioxide capture at ambient conditions without adsorbing nitrogen.
• The study highlights the structure-property relationship in CMPs for selective gas adsorption.

Conclusions:

• The developed CMPs show significant potential for reversible iodine capture and selective carbon dioxide separation.
• Tailoring macrocyclic components in CMPs allows for fine-tuning adsorption properties for specific gas applications.
• These findings contribute to the development of advanced materials for environmental remediation and gas storage.