Direct Observation of Hemithioindigo-Motor Unidirectionality

Area of Science:

• Supramolecular Chemistry
• Organic Chemistry
• Materials Science

Background:

• Hemithioindigo molecular motors exhibit rapid unidirectional rotation under visible light, complicating mechanistic studies.
• Understanding the precise working mechanism of these motors is crucial for their application in advanced technologies.

Purpose of the Study:

• To significantly slow down the rotation of hemithioindigo molecular motors to enable detailed mechanistic analysis.
• To observe and characterize all intermediate states during the motor's light-induced rotation.
• To confirm the complete unidirectionality of the motor's motion.

Main Methods:

• Synthesis of sterically hindered hemithioindigo motor derivatives.
• Low-temperature proton nuclear magnetic resonance (¹H NMR) spectroscopy.
• Complementary analytical techniques for state elucidation.

Main Results:

• Successfully synthesized sterically hindered hemithioindigo motors with considerably slowed rotation.
• Observed and identified all four transient intermediate states during the motor's operational cycle.
• Confirmed the complete unidirectionality of the visible-light-induced rotation process.

Conclusions:

• The development of slowly rotating hemithioindigo motors provides unprecedented insight into their working mechanism.
• This advancement opens new avenues for visible-light-controlled molecular machines in catalysis, smart materials, and supramolecular chemistry.