A Dual Vibrational Probe Framework for Studying Solvation in Highly Heterogeneous Molecular Environments

Vibrational probes are essential for studying interactions and dynamics of complex environments, but they often rely on computer simulations to describe the system. Here, a dual-IR-probe approach based on the alkyne molecular framework is demonstrated for two probes: MOC (low polarity) and TFPB (nonpolar). In these dual-probes, the secondary IR-active group allows their precise localization, while the alkyne group is used to probe the dynamics. The approach is validated in two complex liquids: a deep eutectic solvent (DES) and a water micelle. In the DES, the dual-IR scheme experimentally locates MOC in one specific domain. In water micelles, MOC and TFPB localize selectively at the interface and within the hydrophobic core, respectively, providing an independent characterization of the two environments. The results demonstrate that the alkyne-based dual-probe is a versatile molecular framework for characterizing the structure, interactions, and dynamics of complex liquids using only experimental methods.