A van der Waals density functional investigation of carboranethiol self-assembled monolayers on Au(111)

Abstract

Isolated and full monolayer adsorption of various carboranethiol (C 2 B 10 H 12 S) isomers on gold (111) surface have been investigated using both the standard and van der Waals density functional theoretical calculations. The effect of differing molecular dipole moment orientations on the low energy adlayer geometries, the binding characteristics and the electronic properties of the self-assembled monolayers of these isomers have been studied. Specifically, the binding energy and work function changes associated with different molecules show a correlation with their dipole moments. The adsorption is favored for the isomers with dipole moments parallel to the surface. Of the two possible unit cell structures, the (5×5) was found to be more stable than the ( √ 19 × √ 19)R23.4 • one.

Influence of Terminal Carboxyl Groups on the Structure and Reactivity of Functionalized m-Carboranethiolate Self-Assembled Monolayers

“…5,[17][18][19][20] In this regard, special attention has been paid to the dipole moment orientation, which is mainly given by the positioning of the carbon atoms in the cage, and to its effect on work function changes. [21][22][23][24][25] Building on these advances, we prepared two isomeric bifunctional cage molecules based on the meta-carborane skeleton, juxtaposing them to their organic analogue, metamercaptobenzoic acid, as well as the previously studied para-isomer as building blocks for SAMs. Both new isomers show practically identical orientations of functional groups with respect to the centroid of the meta-carborane cage but differ in chemical and physical properties as determined by the electron-donating and withdrawing properties of the molecular cage scaffold.…”

Carboxyl and Amine Functionalized Carboranethiol SAMs on Au(111) : A Dispersion Corrected Density Functional Theory Study

“…Possible adsorption sites were systematically examined for pure carborane derivatives previously. [38] In the cases of functionalized CTs, atop, bridge and hollow sites were considered as the initial adsorption configurations. For the full monolayer, two possible conformations were taken into account.…”

“…For instance, work function of metal electrodes used in the design of organic electronic devices can be modified by adjusting dipole moments of different thiol SAMs attached to those electrodes. Thiol SAMs provide a great advantage in many applications, and therefore, has been the subject of many experimental [11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30] and theoretical [31][32][33][34][35][36][37][38][39][40] studies. Moreover, additional functional groups were shown to be effective in modification of the work function of gold substrates.…”

Selection of an Appropriate Basis Set for Accurate Description of Binding Energy: A First Principles Study

“…Over the years there has been significant improvements in computer technology which has boosted up theoretical calculations carried out in physics, chemistry and material science and engineering [1][2][3][4][5]. Electronic structure calculations which try to understand the characteristics of system by solving Schrödinger equation comprehend most of the theoretical calculations in physics and chemistry [6][7][8][9][10][11][12]. However, exact solution of Schrödinger equation is only possible for a limited number of problems like particle in a box, hydrogen atom and harmonic oscillator.…”

“…Electronic structure calculations which try to understand the characteristics of system by solving Schrödinger equation comprehend most of the theoretical calculations in physics and chemistry [6][7][8][9][10][11][12]. However, exact solution of Schrödinger equation is only possible for a limited number of problems like particle in a box, hydrogen atom and harmonic oscillator.…”