Thermal E/ Z Isomerization in First Generation Molecular Motors

Area of Science:

• Molecular Chemistry
• Supramolecular Chemistry
• Physical Chemistry

Background:

• First-generation molecular motors are crucial for nanoscale applications.
• Understanding their thermal stability and isomerization pathways is essential for designing efficient systems.
• E/Z isomerization is a key process in the function of many molecular motors.

Purpose of the Study:

• To determine the thermal E/Z isomerization barrier of a specific first-generation molecular motor.
• To investigate the thermodynamic stability difference between the E and Z isomers.
• To elucidate the mechanism of thermal isomerization in molecular motors.

Main Methods:

• Utilized circular dichroism (CD) spectroscopy to monitor spectral changes during thermal isomerization.
• Quantified the activation Gibbs energy (ΔG‡) of the isomerization process.
• Employed Density Functional Theory (DFT) calculations to support experimental findings and analyze electronic structure.

Main Results:

• The stable (E)-isomer directly converted to the stable (Z)-isomer without photochemical induction.
• The activation Gibbs energy for the thermal isomerization was determined to be 123 kJ mol⁻¹.
• DFT calculations revealed that the (Z)-isomer is approximately 11.4 kJ mol⁻¹ more stable than the (E)-isomer.

Conclusions:

• The study successfully quantified the thermal E/Z isomerization barrier for a first-generation molecular motor.
• The results provide valuable insights into the thermal stability and isomerization dynamics of molecular motors.
• This work contributes to the fundamental understanding required for the development of advanced molecular machines.