Chirality induction and amplification in supramolecular systems exhibiting vibrational optical activity

Area of Science:

• Spectroscopy
• Chiroptical methods
• Supramolecular chemistry

Background:

• Vibrational optical activity (VOA), encompassing vibrational circular dichroism (VCD) and Raman optical activity (ROA), offers detailed molecular structure and chirality insights, often exceeding electronic optical activity (EOA).
• The practical application of VOA is limited by its inherently weak signal intensity, typically 10⁻⁴-10⁻⁵ of the parent IR or Raman signals.
• Enhancing VOA signal intensity is crucial for expanding its utility, driving research into various amplification strategies.

Purpose of the Study:

• To review recent advancements in VOA applications for analyzing supramolecular systems, particularly biogenic ones.
• To highlight how these systems can induce and amplify chirality, leading to enhanced VOA signals.
• To focus on specific biogenic assemblies that demonstrate significant VOA enhancement.

Main Methods:

• Discussion of up-to-date studies on VOA applications.
• Analysis of supramolecular systems, with an emphasis on biogenic assemblies.
• Focus on techniques for measuring and enhancing VOA signals.

Main Results:

• Biogenic supramolecular systems can induce and amplify chirality, leading to substantial VOA signal enhancement.
• Amyloid fibrils exhibit exceptionally large vibrational circular dichroism (VCD) signals.
• Carotenoid aggregates show resonantly enhanced Raman optical activity (ROA) signals.

Conclusions:

• VOA techniques are powerful tools for analyzing molecular structure and chirality.
• Supramolecular self-assembly, especially in biogenic systems like amyloid fibrils and carotenoid aggregates, offers a promising route to significantly enhance VOA signals.
• Further research into these systems can unlock broader applications of VOA in structural analysis.