A foldable cyclic oligomer: chiroptical modulation through molecular folding upon complexation and a change in...

Area of Science:

• Supramolecular Chemistry
• Organic Chemistry
• Chirality Studies

Background:

• Foldable cyclic oligomers offer unique structural dynamics.
• Chirality transfer in molecular systems is crucial for advanced materials.

Purpose of the Study:

• To investigate the supramolecular chirality transfer from external guests to a foldable cyclic oligomer.
• To understand the role of internal chirality in modulating host-guest complexation.

Main Methods:

• Synthesis of a foldable cyclic oligomer (1) with terephthalamide units.
• Complexation studies with ditopic chiral guests (2).
• Analysis of conformational changes and helicity preferences.

Main Results:

• The cyclic oligomer (1) exists as enantiomeric forms, adopting specific helicities upon guest complexation.
• External chirality of guests (S,S)-2 or (R,R)-2 is transferred to induce preferred helical senses in the oligomer.
• Internal chirality of the host (1b) modulates signals and cooperates/competes with guest chirality, favoring specific helicities when matched.

Conclusions:

• The study demonstrates effective supramolecular chirality transfer and control over dynamic helicity in a foldable macrocycle.
• Host-guest interactions dictate conformational preferences and signal responses based on matched or mismatched chirality.