Development of Classical Force Fields for Interfaces between Single Molecules and Au.

Interfaces between metals and organic materials play an essential role in molecular surface science, photovoltaics, or molecular electronics. Modeling the evolution of interface geometry over sufficiently long timescales requires an accurate parameterization of the relevant metal-molecule interactions. Here, we describe a method for calculating interface parameters from reference density functional theory calculations of small metal-molecule complexes.

Origin of the Electron Transport Properties of Aromatic and Antiaromatic Single Molecule Circuits.

Antiaromatic molecules have been predicted to exhibit increased electron transport properties when placed between two nanoelectrodes compared to their aromatic analogues. While some studies have demonstrated this relationship, others have found no substantial increase. We use atomistic simulations to establish a general relationship between the electronic spectra of aromatic, antiaromatic, and quinoidal molecules and illustrate its implications for electron transport.

Preservation of the donor-acceptor character of a carbazole-phenalenone dyad upon adsorption on Pt(111).

Donor-acceptor molecules are a subject of great attention due to their immense potential in molecular electronics and photovoltaics. Despite numerous extensive studies demonstrating their functionality in solution, the donor-acceptor character is usually lost upon adsorption on a conducting substrate. Here the concept of breaking the conjugation between the donor and acceptor unit by insertion of a bridge is used.

Cyclopropenylidenes as Strong Carbene Anchoring Groups on Au Surfaces.

The creation of stable molecular monolayers on metallic surfaces is a fundamental challenge of surface chemistry. N-Heterocyclic carbenes (NHCs) were recently shown to form self-assembled monolayers that are significantly more stable than the traditional thiols on Au system. Here we theoretically and experimentally demonstrate that the smallest cyclic carbene, cyclopropenylidene, binds even more strongly than NHCs to Au surfaces without altering the surface structure.

Direct Au-C contacts based on biphenylene for single molecule circuits.

We propose a novel platform for stable and highly conducting single molecule electronics and characterize its mechanical, electronic and conducting properties using ab initio simulations. We study a biphenylene-based molecular architecture on gold and consider that the antiaromatic instability of biphenylene leads to the breaking of internal carbon-carbon bonds and subsequent formation of Au-C covalent bonds with the substrate. In the resulting conformation the conjugated rings have a large twist angle and stand almost upright on the surface.

Highly-conducting molecular circuits based on antiaromaticity.

Aromaticity is a fundamental concept in chemistry. It is described by Hückel's rule that states that a cyclic planar π-system is aromatic when it shares 4n+2 π-electrons and antiaromatic when it possesses 4n π-electrons. Antiaromatic compounds are predicted to exhibit remarkable charge transport properties and high redox activities.