Guest-induced supramolecular chirality transfer in [2]pseudorotaxanes: experimental and computational study

Area of Science:

• Supramolecular Chemistry
• Chiral Recognition
• Spectroscopy

Background:

• Chirality transfer is crucial for creating chiral supramolecular assemblies.
• Understanding host-guest interactions is key to controlling chirality in molecular systems.

Purpose of the Study:

• To investigate the factors governing chirality transfer from chiral molecules to supramolecular assemblies.
• To explore the induction of circular dichroism (CD) signals in [2]pseudorotaxanes.

Main Methods:

• Construction of [2]pseudorotaxanes via noncovalent interactions between chiral binaphthalene crown ethers and achiral ammonium salts.
• Spectroscopic analysis, including circular dichroism (CD) measurements.
• Computational studies using density functional theory (DFT) and time-dependent DFT (TD-DFT).

Main Results:

• New CD signals were observed exclusively in [2]pseudorotaxanes formed between binaphthalene crown ethers and an anthryl-containing guest molecule.
• The binaphthalene host groups induced chirality in the supramolecular assembly.
• DFT/TD-DFT calculations confirmed intermolecular chiral induction between the anthryl guest and naphthalene host groups as the primary cause.

Conclusions:

• Chirality transfer to supramolecular assemblies can be achieved through specific host-guest interactions.
• The anthryl chromophore plays a critical role in enabling chiral induction within the [2]pseudorotaxane system.
• Computational modeling provides valuable insights into the mechanisms of intermolecular chiral induction.