Molecular Dynamics of Steroidal Rotors Probed by Theoretical, Spectroscopic and Dielectric Methods

Area of Science:

• Supramolecular Chemistry
• Materials Science
• Organic Chemistry

Background:

• Molecular rotors are key components in developing advanced functional materials.
• Amphidynamic crystals require molecular units with controlled rotational dynamics.
• Steroidal scaffolds offer rigid frameworks for designing molecular rotors.

Purpose of the Study:

• To synthesize and characterize novel steroidal molecular rotors with fluorine-substituted phenyl rotators.
• To investigate the conformational dynamics and behavior of these rotors in solution and solid states.
• To explore their potential applications in amphidynamic crystals.

Main Methods:

• Synthesis and characterization of three steroidal molecular rotors with varying fluorine substitution.
• Vibrational spectroscopy (Raman, FT-IR) and electronic circular dichroism (ECD) for structural and conformational analysis.
• Dielectric response measurements and Density Functional Theory (DFT) calculations for understanding dynamics and electronic properties.

Main Results:

• Angle-dependent polarized Raman spectra confirmed sample crystallinity.
• Nearly frequency and temperature-independent permittivity indicated low-frequency stator motion.
• High conformational flexibility in solution (low ECD) contrasted with restricted rotation in solid-state (significant ECD).

Conclusions:

• The study successfully synthesized and characterized novel steroidal molecular rotors.
• Distinct conformational behaviors were observed in solution and solid states, influenced by rotational restriction.
• These findings provide insights into the design principles for molecular rotors in amphidynamic crystals and other applications.