Revealing the Interplay Between Covalent and Non-Covalent Interactions Driving the Adsorption of Monosubstituted Thiourea Derivatives on the Au(111) Surface

Abstract

This work reports a detailed study of the adsorption of thiourea and seven monosubstituted thiourea derivatives on the Au(111) surface based on self-consistent periodic density functional theory (DFT) calculations. We included in our analysis the most stable cis and trans configurations for each considered monosubstituted derivative. Different functional groups have been selected for the derivatives in order to address the electron-donating/withdrawing effect on the strength of the molecule-metal interaction.The comparison of the cis and trans-derivatives revealed interactions of different nature between the molecules and the Au(111) surface. We have been able to disentangle these interactions analyzing the charge density difference plots, the projected density of states (pDOS) and the non-covalent interactions (NCI). For the non-substituted thiourea and all the studied derivatives, besides the strong S-Au bond, it has been observed an Au• • •H-N interaction similar to a hydrogen bonding, which is caused by the charge transfer from the molecules to the Au(111) surface inducing a charge counterbalancing: Au δ− H δ+ N δ− . Furthermore, π-Au interactions between the functional group of the derivatives and the Au(111) surface, mainly observed for the cis-derivatives, were highlighted by the NCI plots. In some particular cases it was also possible to distinguish long range interactions of the type lone pair-Au. The present results provide insight into a new kind of organic molecule-metal surface interaction, opening the way for the synthesis of potential nanodevices with diverse applications such as sensing (biosensors or atmospheric sensors), optoelectronics, pollution control, or energy conversion.

Ultrafast Dynamics of Electronic Resonances in Molecules Adsorbed on Metal Surfaces: A Wave Packet Propagation Approach

“…Because Δ V Met+Mol DFT vanishes in the asymptotic region, we can introduce an approximation that greatly reduces the computational load and makes the problem of the quasistationary states localized on the single adsorbed molecule, and decaying into the metal, numerically accessible. Indeed, the standard codes based on DFT are able to deal with enough atoms to describe properly many of the processes of interest such as molecular adsorption geometry, formation of molecule–metal bond, and so forth. − Typically, 4–5 atomic layers are enough for a proper description of these properties, provided a large enough supercell in the lateral direction so that the effects owing to periodic representation of the system inherent to this codes can be neglected. However, if one is interested in the decay of molecule localized states into the metal, or in the photoemission, the computational domain has to be extended parallel to the surface as well as deep inside the metal and into the vacuum.…”

“…Indeed, the standard codes based on DFT are able to deal with enough atoms to describe properly many of the processes of interest such as molecular adsorption geometry, formation of molecule-metal bond, etc. [89][90][91][92][93][94][95][96][97][98][99][100][101][102] Typically, 4-5 atomic layers are enough for a proper description of these properties, provided large enough supercell in the lateral direction so that the effects owing to periodic representation of the system inherent to this codes can be neglected. However, if one is interested in the decay of molecule localized states into the metal, or in the photoemission, the computational domain has to be extended parallel to the surface as well as deep inside the metal and into the vacuum.…”

Unravelling the effects of functional groups on the adsorption of 2-mercaptobenzothiazole on a copper surface: a DFT study

“…46,47 The sign(l 2 ) indicates whether NCI plots depict non-bonded interactions (for l 2 4 0) or bonded interactions (for l 2 o 0). [46][47][48] Calculations involving NCI plots were executed using the Critic2 code. 46,47 Visualization of charge density difference and NCI plots was facilitated using VESTA software.…”

A comprehensive investigation of the plasmonic-photocatalytic properties of gold nanoparticles for CO2 conversion to chemicals

“…Several similar charge transfer processes have been reported for metal-molecule structures, such as CO 97,98 and NO, 99,100 and organic compounds on metals. 101,102 This back bonding is not present in the hydrocarbons due to the lack of low-energy π* orbitals. C, CH, CH 2 and CH 3 represent the LUMO with a relatively low energy that leads to an effective charge transfer from the occupied surface state to the molecule.…”