Macroscopic Homochiral Twist Enables Continuous In Situ Rotational Movement in Photomechanical Assemblies

Area of Science:

• Supramolecular chemistry
• Materials science
• Nanotechnology

Background:

• Continuous in situ rotational movement in molecular assemblies is crucial for mimicking biological rotary motors and energy transduction.
• Existing light-driven motions in molecular assemblies are often limited, hindering applications in advanced mechanical systems.

Purpose of the Study:

• To design and construct a macroscopic homochiral twisted assembly capable of continuous rotational movement under light irradiation.
• To investigate the factors influencing the speed and direction of the light-driven rotation.

Main Methods:

• Introduction of chirality into molecular assembly to create a macroscopic homochiral twisted structure at the microscale (BNP twist).
• Irradiation of the assembly with UV light (365 nm) to induce and observe rotational movement.
• Systematic control of light intensity and assembly size to regulate rotation speed and analysis of light exposure geometry for direction control.

Main Results:

• The constructed BNP twist assembly demonstrated continuous rotation under UV light.
• Rotation speed was successfully regulated by adjusting light intensity and assembly size.
• The direction of rotation was influenced by geometrically unequal light exposure due to the twisted structure.

Conclusions:

• The light-driven continuous mechanical rotation is attributed to amplified molecular isomerization and the unique properties of the chiral twisted structure.
• This work presents a viable method for designing continuous photomechanical assemblies.
• Potential applications include light-driven mechanical systems, micro/nanorobots, and photoelectric devices.