Rotation in an Enantiospecific Self-Assembled Array of Molecular Raffle Wheels

Area of Science:

• Supramolecular Chemistry
• Surface Science
• Nanotechnology

Background:

• Tailored nano-spaces are crucial for controlling molecular behavior, including enantioselective adsorption and motion.
• Self-assembled molecular networks offer precise control over guest molecule environments.

Purpose of the Study:

• To report the spontaneous assembly of a dynamic system comprising a rigid kagome network hosting guest molecules.
• To investigate the enantiomorphic adsorption and selective rotational motions of guest molecules within the network.
• To elucidate the molecular mechanisms governing guest anchoring and motion.

Main Methods:

• Spontaneous self-assembly of 2,6-bis(1H-pyrazol-1-yl)pyridine-4-carboxylic acid on Ag(111) to form a kagome network.
• Temperature-dependent scanning tunneling microscopy (STM) to study molecular dynamics and anchoring.
• Density functional theory (DFT) investigations to analyze molecular interactions and energy landscapes.

Main Results:

• A dynamic system was successfully assembled, with a kagome network hosting guest molecules on Ag(111).
• The network facilitated enantiomorphic adsorption and allowed selective rotational motions of the guest.
• STM revealed distinct guest anchoring orientations switching with a 0.95 eV thermal barrier, influenced by H-bonding.
• DFT confirmed the molecular pirouette and the role of H-bond dynamics in the energy landscape.

Conclusions:

• The kagome network on Ag(111) provides tailored nano-spaces for controlled molecular adsorption and motion.
• Enantioselective adsorption and dynamic anchoring of guest molecules are achieved through the interplay of the network and the silver surface.
• Hydrogen bonding plays a key role in stabilizing and modulating the rotational dynamics of the guest molecules.