Substituted Benzene Derivatives on the Cu(111) Surface

First-principles calculations on substituted benzenes adsorbed to the Cu(111) surface illustrate that quintessential activating/deactivating substituents can be used to control the amount of charge transfer at the adsorbate–surface junction. A frontier orbital perspective is employed to develop an understanding of the factors influencing the magnitude and direction of electron donation upon absorption and the strength of the metal–organic interaction. Classic activating groups generally increase and prototypical deactivating groups decrease the amount of charge transferred from the adsorbate to the metal surface. In the case of trihalogenated benzenes, the donor strength is inversely proportional to the electronegativity of the substituent. An interplay of the Coulomb repulsion (a result of the charge transfer) between the adsorbate molecules along with attractive supramolecular forces (i.e., hydrogen bonding, van der Waals interactions) is important in determining the network architecture.