Experimental two-dimensional infrared spectra of methyl thiocyanate in water and organic solvents.

This article focuses on the vibrational spectroscopy of methyl thiocyanate (MeSCN) as a transparent-window probe to characterize local environments and dynamics in biological and chemical systems. It presents a comprehensive, experimentally consistent dataset of infrared absorption and ultrafast two-dimensional infrared (2D IR) spectra of MeSCN in fourteen solvents, including protic, polar, and non-polar types, to serve as a benchmark for developing theoretical models. Key findings include the influence of hydrogen bonding and π-interactions on spectral line shapes and frequencies, the applicability of a simplified Kamlet–Taft parameter combination to predict center frequencies, and the identification of solvent-dependent ultrafast dynamics through nodal line slope analysis. Cryogenic measurements reveal subpopulations contributing to peak asymmetry in aprotic solvents, highlighting complexities in spectral interpretation. The publicly available dataset aims to support future advancements in modeling vibrational probes in diverse environments, particularly for applications in biochemical systems.