Information, Section S2.3.1). For more details on the construction of the sandwich structures, see the Supporting Information, Section S2.3.1. For pushing or pulling simulations, the structures were divided into a handle, a mobile, and a fixed region (see Figure ). Forces on atoms in the handle and fixed regions were set to zero in all directions. The velocities of atoms in the fixed region was additionally set to zero, while atoms in the mobile region were allowed to move freely, according to the laws of motion, and atoms in the handle region moved "downwards", towards the other gold surface, with a constant velocity of 2 × 10 -4 Å/fs (with 1 Å/fs = 10 5 m/s) for 40-50 ps, depending on the length of the ligand. The potential energy vs. the surface-to-surface distance were extracted for every 1000th step of a trajectory (pushing for 1000 steps corresponds to a surface-to-surface distance change of 0.1 Å) and plotted against each other (as shown in Figure and Figure in the Supporting Information).