Molecular-Enhanced Raman Spectroscopy Driven by Phosphoester Electron-Transfer Bridge

Area of Science:

• Surface-enhanced Raman Spectroscopy (SERS)
• Charge Transfer (CT) Mechanisms
• Molecular Spectroscopy

Background:

• Surface-enhanced Raman scattering (SERS) relies on both electromagnetic and charge transfer (CT) mechanisms.
• The contribution of CT mechanisms to SERS is often limited by low CT efficiency.

Purpose of the Study:

• To introduce molecular-enhanced Raman spectroscopy (MERS) as a novel technique.
• To develop a strategy for inducing strong CT-enhanced Raman signals using a phosphoester (POE) electron-transfer bridge.

Main Methods:

• Development of a phosphoester (POE) molecule as an electron-transfer bridge.
• Application of MERS with POE for analyzing various mono-, bis-, and trisaminobenzene compounds.
• Spectroscopic analysis and density functional theory (DFT) calculations to elucidate the enhancement mechanism.

Main Results:

• Demonstrated an excellent POE-enhanced Raman effect for diverse aminobenzene analytes.
• Quantification revealed a MERS enhancement ratio of up to 87% and an enhancement factor of approximately 10^9.
• Confirmed the role of intermolecular hydrogen bonds in promoting CT and enhancing Raman signals via DFT calculations.

Conclusions:

• The study successfully demonstrates the feasibility of MERS for achieving highly CT-enhanced Raman signals.
• The developed POE-based strategy offers a significant advancement in Raman spectroscopy sensitivity and efficiency.