Light-Driven Dual Rotary Molecular Motors and Beyond

Area of Science:

• Supramolecular Chemistry
• Nanotechnology
• Organic Chemistry

Background:

• Biological molecular machines like ATP synthase utilize nanoscale rotary motion for efficient task execution.
• Artificial molecular machines, particularly light-driven overcrowded-alkene motors, have demonstrated unidirectional rotation.
• Extending single-rotor systems to dual rotary molecular motors presents opportunities for studying emergent behaviors and control.

Purpose of the Study:

• To develop and investigate symmetric and mixed light-driven dual rotary molecular motors.
• To gain mechanistic insights into coupled motion and directional control in multi-rotor systems.
• To explore the potential of dual motors for next-generation molecular machines and materials.

Main Methods:

• Synthesis and characterization of fluorene-based and oxindole-based dual rotary motors.
• Photochemical and thermal studies to analyze rotation mechanisms, including ultrafast spectroscopy.
• Investigation of steric effects, substitution patterns, and solvent influences on rotary performance.

Main Results:

• Developed dual motors where a pseudoasymmetric center dictates directionality and steric tuning controls speed.
• Identified coupled rotary motion in oxindole-based dual motors, revealing novel relaxation pathways and collective behavior.
• Created mixed-rotor motors capable of sustaining two distinct unidirectional rotational frequencies, controlled by external factors.

Conclusions:

• Dual rotary motors serve as a versatile platform for studying coupled motion, asymmetric photochemistry, and multifrequency rotation.
• These systems demonstrate unprecedented control over rotational behavior, unmatched in natural or synthetic counterparts.
• Future designs with multiple coupled rotors promise programmable, cooperative nanoscale motion for advanced applications.