Substrate Registry in Disordered Layers of Large Molecules

Abstract

We present a statistic evaluation of the azimuth orientations of flat-adsorbed oligopyridine molecules in disordered adlayers on Au(111) and (111) oriented Ag-adlayers on Ru(0001). On both surfaces, we find a strong preference for a set of twelve angles, which belong to one specific, unsymmetrical alignment and its symmetry equivalents. These angles are also those that exclusively occur in more densely packed, ordered structures on the same surfaces. We describe a geometric fitting algorithm, which correctly predicts these angles, and which only requires the substrate lattice and the positions of the nitrogen atoms within the flat-adsorbed molecule as input parameters. Such predictions are particularly valuable to reduce the parameter space in structure simulations [C. Rohr, M. Balbás Gambra, K. Gruber, E. C. Constable, E. Frey, T. Franosch, B. A. Hermann, Nano Lett. 2009, 10, 833].

Sequential nested assembly at the liquid/solid interface

“…To verify this, experiments were performed with 3BPEB-OH. The three additional OH groups compared to 3BPEB-H should increase the interaction of the star molecule with the network and/or the substrate and, thus, affect the switching rate of the molecule, similar to a monocomponent system 55,56 which demonstrated a packing dependent influence of sterical factors and intermolecular interaction on molecular rotation. This is fully confirmed as evidenced by the STM image shown in Fig.…”

Growth of an oligopyridine adlayer on Ag(100) – A scanning tunnelling microscopy study

“…In analogy to the previous analyses of 2,4 0 -BTP adlayers on Au(111) and Ag(111), we used the points-to-lattice model to determine the optimum orientation of the admolecules. [16][17][18] This assumes that the orientation of the molecules is mainly governed by effective, pairwise interactions between the metal surface atoms and reactive centres within the molecules. Even without specific assumptions about the actual interaction potentials it is reasonable to assume that the optimum alignments are characterized by a minimized average distance between the reactive centres and the closest subjacent metal atoms.…”

“…1a) on hexagonal Ag(111) films and Au(111) surfaces, where predictions based on this model were found to fully agree with experimental findings. [16][17][18] In the present paper, we will further substantiate the potential of this approach by applying it to a system with a different surface symmetry, using the adsorption of 2,4 0 -BTP on Ag(100) as example. We will first give an overview on the evolution of structures with increasing coverage in the sub-monolayer regime, up to the formation of a close-packed, well ordered monolayer (2D crystal).…”

“…Hence, there is a need for more detailed, quantitative information on the relation between substrateadsorbate interactions ('single molecule adsorption energy') and the orientation of adsorbed molecules or complete adlayers. We have recently proposed a simple scheme for estimating the variation in molecule-substrate interaction energy ('points-to-lattice scheme') [16][17][18] upon rotation and translation of individual admolecules, which leads to system specific preferential azimuth angles that could in a next step be used in Monte-Carlo type structure simulations. The physical/ chemical basis of this model is the rather localized interaction between hetero atoms such as O, 19,20 S, 21 or N [16][17][18][22][23][24][25] in the admolecules and the underlying surface.…”

“…We have recently proposed a simple scheme for estimating the variation in molecule-substrate interaction energy ('points-to-lattice scheme') [16][17][18] upon rotation and translation of individual admolecules, which leads to system specific preferential azimuth angles that could in a next step be used in Monte-Carlo type structure simulations. The physical/ chemical basis of this model is the rather localized interaction between hetero atoms such as O, 19,20 S, 21 or N [16][17][18][22][23][24][25] in the admolecules and the underlying surface. The validity of this model was demonstrated for adsorption of 2-phenyl-4,6-bis (6-(pyridine-2-yl)-4-(pyridine-4-yl)pyridine-2-yl)pyrimidine (2,4 0 -BTP) 14 (see Fig.…”