Mueller matrix polarimetry reveals chiroptical properties of metal chelates in solutions

Proper characterization of molecular chiroptical properties is vital for organic chemistry and drug development. Nonetheless, narrow spectral ranges and the necessity for specialized equipment often limit traditional methods such as optical rotatory dispersion and electronic circular dichroism. Here, we introduce Mueller matrix polarimetry (MMP) as a more versatile tool for chiroptical analysis, capable of simultaneously capturing circular dichroism and optical rotatory dispersion spectra across ultraviolet to near-infrared wavelengths in a single measurement. We applied MMP to chiral metal complexes of Al, Mn, and Co, commonly used as catalysts in asymmetric syntheses. Using a robust experimental methodology, MMP distinguished enantiomeric forms and provided reliable chiroptical information by leveraging the inherent relationship between circular dichroism and optical rotatory dispersion. We interpreted our findings on the basis of density functional theory simulations, compared them to traditional electronic circular dichroism and absorption spectroscopies, and performed the Kramers-Kronig analysis. The combined approach of chiroptical MMP and ab-initio, for example, reveals delicate near-infrared chiroptical spectra of a neutral cobalt metal complex. Although MMP is more commonly used for solid state, the developed experimental protocol significantly expands its capabilities to solutions. It allows measurements without the need for both enantiomers and offers new insights into molecular chirality with potential applications across traditional and interdisciplinary branches of science and industry.