A Molecular Strategy for Raman Enhancement

Surface-Enhanced Raman Spectroscopy (SERS) drives ultrasensitive molecular detection by amplifying Raman signals orders of magnitude at trace concentrations, enabling breakthroughs in biomedical diagnostics, environmental monitoring, and nanotechnology. Its mechanism relies on the creation of a nanostructured rough surface where the synergistic interplay of localized surface plasmon resonance and chemical charge-transfer interactions collectively amplify Raman scattering signals. Herein, we developed a molecular-level platform which utilized discrete molecules, rather than relying on nanostructured materials, to amplify Raman signals through ion pair formation. The donor metal complex of [Ni(dmit) ₂ ] ⁻ (dmit = 2-thioxo-1,3-dithiol-4,5-dithiolate) could detect molecules with high sensitivity through strong intermolecular charge transfer interactions. These findings shed light into the mechanism of how charge transfer enhances Raman signal from the molecular-level, it also holds transformative potential by enabling in-situ molecular detection in biological fluids and environmental sensing without nanostructured material constraints.