Redox-responsive host-guest system using redox-active pillar[5]arene containing one benzoquinone unit

Area of Science:

• Supramolecular Chemistry
• Organic Chemistry
• Host-Guest Chemistry

Background:

• Pillar[5]arenes are macrocyclic compounds known for their host-guest properties.
• The redox state of functional groups can significantly influence molecular recognition and binding affinities.

Purpose of the Study:

• To investigate the host-guest complexation behavior of a pillar[5]arene bearing a benzoquinone unit.
• To compare the binding affinity of the oxidized pillar[5]arene with its reduced hydroquinone analog.

Main Methods:

• Synthesis of pillar[5]arene derivatives with benzoquinone and hydroquinone units.
• Host-guest complexation studies using a triazole-substituted 1,4-butylene linker as the guest molecule.
• Characterization of the host-guest complexes.

Main Results:

• The pillar[5]arene with a benzoquinone unit formed a weak host-guest complex with the triazole-substituted linker.
• The reduced pillar[5]arene, containing a hydroquinone unit, formed a significantly more stable host-guest complex with the same linker.
• The redox state of the pillar[5]arene critically affects its binding affinity.

Conclusions:

• The hydroquinone moiety in pillar[5]arenes enhances host-guest complex stability compared to the benzoquinone form.
• Redox-responsive pillar[5]arene systems offer tunable host-guest properties for molecular recognition applications.