Fabrication of a Complex Two-Dimensional Adenine–Perylene-3,4,9,10-tetracarboxylic Dianhydride Chiral Nanoarchitecture through Molecular Self-Assembly

Abstract

Tailoring complex organic nanoarchitectures is the focus of recent research interest for developing novel nanostructured materials. 1À5 Two-dimensional (2D) molecular nanoarchitectures can be engineered taking advantage of molecular self-assembly. 6À10 These structures can be tailored at the nanometer scale by exploiting intermolecular interactions. Molecules forming hydrogen bonds (H-bonds) are particularly interesting building blocks for creating sophisticated organic architectures 11À14 due to the high selectivity and directionality of these bindings. Various single 15,16 and multicomponent 17À19 H-bonded structures have been created using semiconducting as well as biomolecules. 20 Engineering new molecular bioarchitectures is especially appealing for developing new advanced drug delivery devices and sensors. Engineering multicomponent biomaterials via attaching one molecule to another requires a deep understanding of molecular interactions. Molecular building blocks have to be chemically and structurally compatible to form specific structures. Over the past decade, remarkable progress has been achieved in building on crystal surface molecular assemblies. This has been largely based on a "drop and see" approach (i.e., molecular adsorption followed by molecular arrangement characterization) rather than on the understanding of the underlying processes and interactions. It is widely believed that a more intelligent approach is now required which would allow "design" or "dial" of a structure with specific properties. 21,22 Molecular size and geometry, as well as interaction between molecules, are some of the key parameters determining whether or not molecular self-assembly is possible and what the final outcome will be. For instance, it has been shown that the mixture of adenine and cytosine, both DNA bases, does not lead to the formation of ordered multicomponent structures, 23 whereas several multicomponent structures have been obtained using semiconducting perylene-3,4,9,10-tetracarboxylic-3,4,9,10-dianhydride (PTCDA) molecules mixed pentacene 24 and 2,4,6-triamino-1,3,5-triazine, sym-triaminotriazine. 25 In this paper, we investigate the self-assembly of a nonsymmetric adenine DNA base ( Figure 1a) mixed with symmetric PTCDA molecules ( Figure 1b) on a Au(111)-(22 Â √ 3) surface at room temperature in ultrahigh vacuum. We observed using scanning tunneling microscopy (STM) that the molecules form a complex bicomponent chiral supramolecular network. The unit cell of the 2D PTCDAÀadenine architecture is composed of 14 molecules. The high stability of this architecture relies on PTCDAÀPTCDA and PTCDAÀadenine hydrogen bonding. Density functional theory (DFT) modeling reveals that the PTCDA-based skeleton of this complex nanoarchitecture is stabilized further by the adenine molecules which may take several orientations within the unit cell, rendering the whole monolayer to be adenine-disordered. ' EXPERIMENTAL SECTIONThe substrates were Au(111) films grown on mica. The samples were introduced into the ultrahigh ...

Bicomponent Supramolecular Architectures at the Vacuum–Solid Interface

“…309 This network is composed of rows of PTCDA molecules connected by O…H-C H-bonds (along the red dashed line in Fig. 15.c), forming a large parallelogram pore.…”

Molecular chirality at surfaces

“…When adenine is coadsorbed with perylene-3,4,9,10-tetracarboxylic dianhydride (PTCDA) on Au(111) it forms a mixed structure with 10 PTCDA and four adenine molecules in the unit cell. All adenine adsorbates are homochiral in a given mirror domain [97]. Another example of homochiral self-assembly is pyridylvinyl benzoic acid (PVBA) on Ag(111) [98].…”

Deprotonation-Induced Phase Evolutions in Co-Assembled Molecular Structures

“…One of the most commonly applied techniques for the bottom-up fabrication of supramolecular nanostructures is the molecular self-assembly on surfaces. − Generally speaking, self-assembly is driven by noncovalent intermolecular interactions, such as van der Waals interactions, − hydrogen bonding, − halogen bonding, − π–π stacking, − and electrostatic interactions. − Among the various noncovalent interactions, hydrogen bonding is considered to be one of the most intriguing interactions because of its directionality and ubiquity in bio-systems. Although thorough investigations on monocomponent self-assembled structures have been performed during the past few decades, studies on bicomponent systems on surfaces have seen a rise as well. ,,− In particular, many studies have been focused on the self-assembly of carboxyl and amino derivatives due to their vital importance to the formation of proteins.…”