Water-accelerated π-Stacking Reaction in Benzene Cluster Cation

Area of Science:

• Molecular electronics
• Quantum chemistry
• Materials science

Background:

• Single molecule electron devices (SMEDs) possess unique properties compared to general macromolecules.
• Residual water molecules can significantly influence SMED electronic properties, yet this effect is not well-understood.
• Benzene-based molecular systems are key components in developing advanced electronic devices.

Purpose of the Study:

• To investigate the impact of water molecules (H2O) on the ON-OFF switching behavior of benzene-based molecular devices.
• To elucidate the mechanism by which H2O affects electronic properties in SMEDs.
• To quantify the influence of H2O on pi-stacking formation in benzene molecular systems.

Main Methods:

• Direct ab initio molecular dynamics (AIMD) simulations were employed.
• T- and H-shaped benzene dimers and trimers were modeled as molecular devices.
• Calculations were performed to determine the time scales of pi-stacking formation with and without H2O.

Main Results:

• A single water molecule was found to accelerate pi-stacking formation in benzene molecular electronic systems.
• For benzene dimer cations, H2O reduced stacking formation time from 947 fs to 460 fs.
• For benzene trimer cations, H2O reduced stacking formation time from 1019 fs to 551 fs.
• This acceleration effect was consistent across different theoretical levels.

Conclusions:

• Water molecules have a positive and significant effect on the electronic properties of benzene-based SMEDs.
• H2O facilitates pi-stacking, thereby enhancing the ON-OFF switching characteristics of these devices.
• The findings provide valuable insights into the role of water in molecular electronics and device performance.