Violet Lander (VL) (C108H104) is a large organic molecule that when deposited on Cu (110) exhibited lock-and-key like behavior (Otero et al., Nature Mater. 3, 779 (2004)). In this work we report on a detailed fully atomistic molecular dynamics study of this phenomenon. Our results show that it has its physical basis in the interplay of the molecular hydrogens and the Cu(110) atomic spacing, which is a direct consequence of an accidental commensurability between molecule and surface dimensions. This knowledge could be used to engineer new molecules capable of displaying lock-and-key behavior with new potential applications in nanotechology.PACS numbers: 61.46.+w, 68.37.Lp, With the advent of nanoscience and nanotechnology and the perspective of molecular electronics [1,2,3,4,5,6,7], significant theoretical and experimental efforts have been devoted to the study of the complex interactions involving organic molecular structures and metallic surfaces [8,9,10,11,12,13,14,15]. One essential aspect of these phenomena is to understand how these interactions alter the properties of both molecule and surface. Recent progress has been achieved through the use of UHV-STM (ultrahigh vacuum-scanning transmission microscopy) [10,16] that allowed the identification of important structural and dynamical features related to the behavior of molecular wires adsorved on metallic surfaces.One important family of molecular wires is the socalled "Lander molecules" (because of its resemblance to a Mars surface rover) [17]. These large organic molecules are composed of a rigid polyaromatic π central board and four spacers (legs) of up to eight 3,5-di-tert-butylphenyl σ-bonded to the central board (Fig. 1). These spacers generate a configuration where the phenyl groups are nearly perpendicular to the main board plane by steric crowding. When deposited onto a metallic surface, these conformations allow an electronic decoupling (π-bonded from the metallic surface) to occur. Also, the presence of the tert-butyl groups, which increases the board-surface distance, permits some rotation of the "legs" without significantly reducing this distance. When adsorbed on Cu(100) or Cu(110) surfaces, the Lander molecule can act as a template for selfaccomodating metal atoms at the step edges of the copper substrate, spontaneously generating metallic nanostructures dimensionally commensurable with the Lander

From the interplay of scanning tunneling microscopy and theoretical calculations, we study the chiral self-assembly of achiral HtB-HBC molecules upon adsorption on the Cu(110) surface. We find that chirality is expressed at two different levels: a +/-5 degrees rotation of the molecular axis with respect to the close-packed direction of the Cu(110) substrate and a chiral close-packed arrangement expected for star-shaped molecules in 2D. Out of the four possible chiral expressions, only two are found to exist due the effect of van der Waals (vdW) interactions forcing the molecules to simultaneously adjust to the atomic template of the substrate geometry and self-assemble in a close-packed geometry.

Violet Lander (C(108)H(104)) is a large organic molecule that when deposited on Cu(110) surface exhibits lock-and-key like behavior [Otero et al., Nature Mater. 3, 779 (2004)]. In this work, we report a detailed fully atomistic molecular mechanics and molecular dynamics study of this phenomenon. Our results show that it has its physical basis on the interplay of the molecular hydrogens and the Cu(110) atomic spacing, which is a direct consequence of the matching between molecule and surface dimensions. This information could be used to find new molecules capable of displaying lock-and-key behavior with new potential applications in nanotechnology.