Selective Extraction of C₇₀ by a Tetragonal Prismatic Porphyrin Cage

Area of Science:

• Supramolecular Chemistry
• Materials Science
• Organic Chemistry

Background:

• Research on fullerene receptors is growing due to supramolecular chemistry advancements.
• Noncovalent bonding interactions are key in designing selective molecular hosts.

Purpose of the Study:

• To design and synthesize a novel cationic molecular cage for fullerene recognition.
• To evaluate the cage's binding affinity and selectivity towards C60 and C70 fullerenes.

Main Methods:

• Synthesis of a rhomboid prismatic cyclophane cage from tetraphenylporphyrins and viologen units.
• Characterization of host-guest complexes using HRMS, NMR, UV-vis, and fluorescence spectroscopy.
• Solid-state confirmation via single-crystal X-ray diffraction analysis.

Main Results:

• The molecular cage effectively forms 1:1 host-guest complexes with both C60 and C70 fullerenes.
• The cage exhibits significantly stronger binding affinity for C70 compared to C60.
• Selective extraction of C70 from a C60/C70 mixture (10:1 ratio) was achieved.

Conclusions:

• The designed molecular cage is an excellent receptor for fullerenes.
• The cage demonstrates high selectivity for C70 over C60, indicating potential for fullerene separation.
• This work highlights the utility of supramolecular cages in selective guest binding.