A novel model system for investigating molecular dynamics: selenosteroids

This paper presents a new molecular dynamics system observable in steroidal selenides. The system was investigated using a pair of epimeric selenosteroids derived from the naturally occurring compound hecogenin. These two compounds differ solely in configuration at the C12 stereogenic center and were selected as a model system to probe local motional averaging in the solid state. Comprehensive structural and spectroscopic characterisation was carried out using solid-state CP/MAS NMR spectroscopy, X-ray crystallography, and variable-temperature electron-capture detection (ECD) spectroscopy. Despite minimal structural variation, the epimers exhibited evidence of motional averaging in the solid state, suggesting that local stereochemistry may influence intramolecular motion. These findings demonstrate that selenosteroids, which combine a rigid steroidal stator with a selenium-based rotator, constitute a promising platform for investigating molecular dynamics and may enable the development of a new class of functional materials.