Benzene derivatives adsorbed to the Ag(111) surface: Binding sites and electronic structure

Abstract

Dispersion corrected Density Functional Theory calculations were employed to study the adsorption of benzenes derivatized with functional groups encompassing a large region of the activated/deactivated spectrum to the Ag(111) surface. Benzenes substituted with weak activating or deactivating groups, such as methyl and fluoro, do not have a strong preference for adsorbing to a particular site on the substrate, with the corrugations in the potential energy surface being similar to those of benzene. Strong activating (N(CH3)2) and deactivating (NO2) groups, on the other hand, possess a distinct site preference. The nitrogen in the former prefers to lie above a silver atom (top site), but in the latter a hollow hexagonal-closed-packed (Hhcp) site of the Ag(111) surface is favored instead. Benzenes derivatized with classic activating groups donate electron density from their highest occupied molecular orbital to the surface, and those functionalized with deactivating groups withdraw electron density from the surface into orbitals that are unoccupied in the gas phase. For benzenes functionalized with two substituents, the groups that are strongly activating or deactivating control the site preference and the other groups assume sites that are, to a large degree, dictated by their positions on the benzene ring. The relative stabilities of the ortho, meta, and para positional isomers of disubstituted benzenes can, in some cases, be modified by adsorption to the surface.

Neutral and zwitterionic dopamine species adsorbed on silver surfaces: A DFT investigation of interaction mechanism

“…We can observe that an electron charge transfer of 0.17‐0.24e takes place from the NDA molecule to the Ag surface, in agreement with the results for Δ ρ , allowing the formation of some attractive ionic interaction between adsorbate and substrate. A similar observation was reported for the adenine adsorption on Ag(110) and NN ‐dimethylaniline on Ag(111) . In the latter system, the availability of an aromatic ring to give electron charge was related to the fact that the N(CH 3 ) 2 group is a strong activating substituent of benzene.…”

“…The h C3 height, which can be taken as a measure of the distance between the NDA aromatic ring and the Ag surface, is in the 2.5‐2.9 Å range and follows the S‐111 > S‐110‐a > S‐110‐b height order. These values can be compared to those corresponding to the adsorption of a molecule with aromatic structure and an amino‐like substituent such as NN ‐dimethylaniline adsorbed on Ag(111) where an E ads value of −1.15 eV and a molecule‐surface distance of 2.87 Å were obtained for a stacking configuration. In another comparison, the aromatic nucleobase adenine adsorbed on Ag(110) exhibits an E ads value of −0.32 eV and a molecule‐surface distance of 2.57‐2.63 Å also for a stacking configuration …”

Cooperativity in the Self‐Assembly of the Guanine Nucleobase into Quartet and Ribbon Structures on Surfaces

“…The planarity mimicked the adsorption to the gold surfaces and the structure in the crystal. It was shown previously that gold surfaces had little interactions with the adsorbates, which justified our computational approach . Furthermore, the planar symmetry provided a clear σ–π separation, which was useful in our analysis.…”

Self-assembly of strongly dipolar molecules on metal surfaces

“…19 In fact, studies of benzene on various metal surfaces have also shown that the variations in the PES with the different adsorption sites, top (T), bridge (B), and hollow (H), is fairly small, on the order of a few tens of meV. 19,[29][30][31][32][33] This not only implies that the diffusion barrier is low but it also means that the molecules are not strictly pinned to particular adsorption sites on the surface.…”