Mechanically Interlocked Molecular Rotors on Pb(100).

Area of Science:

• Surface Science
• Materials Science
• Nanotechnology

Background:

• Molecular machines require rotatable and interlocked molecular components.
• Aluminum phthalocyanine (AlPc) on Pb(100) surfaces are investigated for their potential as molecular gears.

Purpose of the Study:

• To demonstrate the feasibility of constructing molecular gears using AlPc molecules on a Pb(100) substrate.
• To investigate the rotational dynamics and mechanical interlocking of AlPc molecules in isolated, dimer, and trimer configurations.

Main Methods:

• Scanning tunneling microscopy (STM) was used to observe and manipulate AlPc molecules.
• Density functional theory (DFT) calculations were employed to understand molecular orientations and interaction potentials.

Main Results:

• Isolated AlPc molecules on Pb(100) exhibit two stable orientations with a low rotation barrier.
• STM-constructed AlPc dimers and trimers show reduced fluctuations and stabilized orientations.
• Collective, induced rotation of all molecules within AlPc trimers was observed, demonstrating mechanical interlocking.

Conclusions:

• AlPc molecules on Pb(100) function as effective molecular gears due to their rotational properties and mechanical interlocking.
• Derived potential functions accurately predict experimental trimer geometries, suggesting applicability to larger molecular assemblies.
• This work provides a foundation for designing and modeling complex molecular machines.