Acid/base- and base/acid-switchable complexation between anionic-/cationic-pillar[6]arenes and a viologen ditosylate...

Area of Science:

• Supramolecular Chemistry
• Materials Science

Background:

• Host-guest chemistry explores molecular recognition and self-assembly.
• Pillararenes are macrocyclic hosts with tunable properties.
• Viologens are guest molecules with redox activity.

Purpose of the Study:

• To construct novel host-guest complexes using water-soluble pillararenes (WP6, CP6) and a viologen ditosylate salt (G·2TsO).
• To investigate the stimuli-responsive behavior of these complexes.
• To demonstrate pH-controlled assembly and disassembly of supramolecular structures.

Main Methods:

• Synthesis of host-guest complexes using anionic pillar[6]arene (WP6) and cationic pillar[6]arene (CP6).
• Titration experiments involving sequential addition of acid (HCl) and base (NaOH).
• Characterization of complex formation and dissociation using spectroscopic techniques (implied).

Main Results:

• Formation of two distinct host-guest complexes: WP6/G2+ and CP6/TsO-.
• The WP6/G2+ complex exhibited pH-switchable behavior upon sequential addition of HCl and NaOH.
• The CP6/TsO- complex demonstrated reversible switching with sequential addition of NaOH and HCl.

Conclusions:

• Successfully constructed pH-responsive host-guest complexes utilizing pillararenes and viologen derivatives.
• Demonstrated the potential for controlling supramolecular assembly and disassembly through external stimuli (pH).
• These findings open avenues for developing smart materials and molecular switches.