Project Details
Projekt
Development of VIPER-Labels to Enable 2D-IR Spectral Diffusion Studies from Femtoseconds up to Microseconds
Subject Area
Physical Chemistry of Molecules, Liquids and Interfaces, Biophysical Chemistry
Term
since 2025
Project identifier
Deutsche Forschungsgemeinschaft (DFG) - Project number 570735703
Understanding dynamics is key in molecular sciences. Two-dimensional infrared (2D-IR) spectroscopy has greatly advanced the study of fast molecular processes in equilibrium. It captures dynamics via measuring spectral diffusion, i.e. frequency fluctuations of molecular vibrations. Yet it faces a fundamental limitation: its time window is restricted to a few picoseconds by the short lifetimes of vibrational excitations. Consequently, a large portion of the dynamics of complex systems, such as proteins, membranes or structured liquids, cannot be accessed. This project pioneers a transformative solution: VIPER 2D-IR spectroscopy (Vibrationally Promoted Electronic Resonance 2D-IR), decouples 2D-IR signal lifetime from vibrational lifetimes. By selectively promoting vibrationally excited molecules into long-lived electronic states via vibronic couplings, VIPER 2D-IR extends observation times for spectral diffusion from the low picosecond into the nanosecond and microsecond regime. However, successful VIPER 2D-IR spectroscopy requires a new class of spectroscopic labels optimized to exploit vibronic couplings. Our mission is to develop these novel VIPER labels. Initial proof-of-concept studies using 2-Isopropylthioxanthon (ITX) demonstrated feasibility, but ITX suffers from very weak signal strength and complications like Fermi resonances distorting the 2D-IR line shapes. To design superior VIPER labels, the project will employ a tiered screening approach, built on a proven collaboration between spectroscopy (Bredenbeck) and synthesis (Heckel), supported by theory (Burghardt). It will begin with commercially available compounds and progress to custom-synthesized labels optimized for the VIPER 2D-IR approach. Ultimately, the project aims to provide a toolbox of versatile VIPER labels that unlock previously inaccessible information on femtosecond to microsecond equilibrium dynamics on a wide variety of complex molecular systems — from structured liquids to biomolecular systems like proteins and membranes.
DFG Programme
Research Grants
Co-Investigator
Professorin Dr. Irene Burghardt
