Seminar Recent developments and perspectives in vibrational spectroscopy

Recent developments and perspectives in vibrational spectroscopy

M. Tommasini

Dipartimento di Chimica, Materiali e Ingegneria Chimica “G. Natta” – Politecnico di Milano, Piazza Leonardo da Vinci, 32 – 20133 Milano (Italy); matteo.tommasini@polimi.it

Vibrational Raman and infrared spectroscopies are powerful tools for linking molecular structure, dynamics, intermolecular interactions, and functional response across systems of varying complexity. In this seminar, I will present an overview of the research directions currently pursued in our group, showing how vibrational spectroscopy, molecular modeling, and quantum-chemical calculations can be integrated.

The first part will focus on the combined use of Raman and infrared spectroscopy, along with DFT calculations, to characterize molecular graphenes and graphene-based materials. In these systems, Raman bands are highly sensitive to the extent of π-conjugation, edge topology, and defect structure, while IR spectroscopy provides complementary structural fingerprints, including evidence of specific cavities or local motifs in nanographenes. A recent development concerns the interpretation of the temperature dependence of the Raman G band as a proxy for the in-plane thermal expansion coefficient, with applications also to soot particles displaying different microstructures. 

The second part will focus on Surface-Enhanced Raman Spectroscopy, with emphasis on approaches for analytical and biomedical applications. I will discuss the case of cenobamate, a recently introduced antiepileptic drug. The results show that SERS enables identification of the drug's diagnostic vibrational bands and monitoring of its response over a concentration range relevant to Therapeutic Drug Monitoring, paving the way for rapid, sensitive spectroscopic methods that may complement conventional chromatographic techniques.  

The third part will be devoted to SIEVE, which represents an active methodological frontier in our group for analyzing molecular dynamics simulations. SIEVE is an open-source graph-based framework designed to extract chemically meaningful information from atomistic trajectories, automatically recognizing molecular connectivity, chemical species, representative microstates, and local environments without requiring predefined bonding information. This provides a scalable and reproducible bridge between MD simulations and electronic-structure calculations, enabling the automated selection of configurations for subsequent quantum-chemical prediction of spectroscopic observables. 

Overall, these activities share a common strategy: using vibrational spectroscopy not only as a characterization technique, but as a quantitative probe of structure, interactions, and molecular dynamics in complex systems.