Nanomechanics of Bidentante Thiolate Ligands on Gold Surfaces

MARTIN E. ZOLOFF MICHOFF; JORDI RIBAS-ARINO; DOMINIK MARX

Bochum

Congreso; 114th General Assembly of the German Bunsen Society for Physical Chemistry; 2015

Deutsche Bunsen-Gesellschaft für physikalische Chemie

Thiolate-gold interfaces have been intensively studied for many decades from using a multitude of experimental and computational techniques. This pronounced interest is due to the many potential technological applications of these hybrid interfaces.Only lately, it has been found that the consideration of the mechanical properties of such molecule/metal hybrids becomes a crucial factor in the design of such nanoscale devices.In the last few years, there has been a growing interest in multidentate thiolate ligands, owed to the search of an enhanced interaction. Nevertheless, information about how these self-assembled monolayers or nanojunctions respond to external stress is conspicuously absent in the literature.In this work, we shed some light into this topic by investigating, by means of electronic structure calculations, the thermal and mechanical desorption of a series of bidentante thiolated ligands (labeled as C1-C4 in the scheme below) adsorbed on a defective gold surface. The focus of our work has been set on the effect of the length of the carbon bridge separating the anchoring sulfur atoms on the rupture of the respective molecule/gold junctions.Our calculations reveal that the preferred thermally activated desorption product is the detachment of the cyclic disulfides, in all cases. In stark contrast, mechanical detachment leads to cyclic gold complexes, in which metal atoms are extracted from the surface and kept in tweezer-like arrangements by the sulfur atoms. Moreover, the flexibility of the carbon chain is shown to crucially influence the mechanical strength of the junction.