Thinking outside the "Blue Box": from molecular to supramolecular pH-responsiveness

Area of Science:

• Supramolecular Chemistry
• Organic Chemistry

Background:

• The well-known cyclobis(paraquat-p-phenylene)cyclophane (blue box) is a key organic receptor.
• Hydrazone-based analogues offer potential for novel supramolecular properties.

Purpose of the Study:

• To develop a new polycationic cyclophane, termed the "red box", as a hydrazone-based analogue.
• To investigate the pH-responsiveness and hydrolytic stability of the novel macrocycle.

Main Methods:

• Synthesis of the
• red box
• cyclophane in aqueous media.
• Characterization of the macrocycle's pH-dependent binding affinities.
• Assessment of the hydrolytic stability of hydrazone linkages.

Main Results:

• The
• red box
• cyclophane was synthesized in excellent yield.
• The macrocycle demonstrated remarkable pH-responsiveness and unusual hydrolytic stability.
• Binding of aromatic substrates was observed in aqueous and organic media, with distinct pH-dependent behavior.

Conclusions:

• The novel hydrazone-based
• red box
• cyclophane exhibits significant pH-responsiveness.
• Its robust hydrolytic stability and versatile binding properties make it a promising candidate for supramolecular applications.