Two-Dimensional Chiral Self-Assembly of Barbituric-Acid-Functionalized Naphthelene Derivatives

Abstract

Scanning tunneling microscopy is used to investigate the self-assembly of two barbiturate-functionalized naphthalene derivatives on a graphite surface on the nanometer scale. The backbone of the molecules has one or two naphthalene units. The two molecules adopt a head-to-head arrangement, stabilized by double hydrogen-bonds between barbituric acid units of the adjacent molecules. The variation of molecular backbone design appears to govern the number of molecular side-by-side neighbors. The shortest compound is thus forming a chiral lamellar-structure, whereas the longest compound is forming a chiral row-structure on the graphite surface.

Concentration-Dependent Conformational Isomerization of Fluorenone-Based Polycatenar in 2D Polymorphic Self-Assembly

“…However, it is difficult to observe the arrangement of LCs at the molecular level. In general, molecular self-assembly is driven by noncovalent interactions, such as hydrogen bonding, − π–π stacking, − dipole–dipole interactions, and van der Waals (vdWs) interactions. − Therefore, a few liquid crystalline molecules that possess a π-conjugated core, alkyl chains, and even polar hydroxyl groups can adsorb on the substrate surface. Scanning tunneling microscopy (STM) is an ideal technique to observe self-assembled nanostructures of liquid crystalline molecules at the liquid/solid interface because of its atomic resolution. − …”

Halogen Substituent Effects on Concentration-Controlled Self-Assembly of Fluorenone Derivatives: Halogen Bond versus Hydrogen Bond

“…As the on-surface bottom-up engineering for novel organic nanoarchitectures with specific electronic properties, molecular self-assembly has received tremendous attention for decades. − With its atomic resolution, scanning tunneling microscopy (STM) has been proven to be a powerful tool to visualize the nanometer-scale self-assembled structures, giving us a better understanding of the nature of self-assembly phenomena on atomically flat conductive surfaces. − It has been widely reported that two-dimensional (2D) self-assembled supramolecular architectures can be tailored by exploiting intermolecular interactions, − including molecule–molecule, molecule–solvent, and molecule–substrate interactions. In addition, designing building blocks and external condition changes (such as solvent and concentration) have been demonstrated to play crucial roles in the formation of 2D nanostructures. − In the field of noncovalent interactions, hydrogen bonding is widely studied for its crucial role in the expression of structural polymorphism. − As a weak noncovalent interaction similar to hydrogen bonding, halogen bonding, used extensively in three-dimensional (3D) crystal engineering, has been considered as an appealing tool in 2D molecular self-assembly in recent years. − In general, halogen bonding that resulted from polarizability of the halogen atom along the C–X axis plays a crucial role in the construction of such 2D self-assembled structures. − To the best of our knowledge, the effects of different halogen substituents in the 2D self-assembly have rarely been investigated. − In previous studies, since the positive potential of the σ-hole along the C–X axis decreased in the order I > Br > Cl > F = 0, the tiny change of halogen substituents can drastically affect the formation of 2D nanoarchitectures, such as lattice matching, diversity, , type of adsorption, and degree of order . However, the internal mechanism of different halogen substituents affecting the self-assembled structure still remains obscure.…”

Complex Structures Resulting from Carboxylic Acid Self-Assembly: Comparison of 2-Naphthoic Acid to Quinaldic Acid and 3-Quinoline Carboxylic Acid

“…2,3 Structures engineered by controlled self-assembly can be simple, such as atoms forming into local islands on metal surfaces 4,5 or thiolate monolayers on gold surfaces, 6,7 with increasing complexity including multilayer structures 8,9 and host−guest composites. 10,11 Additionally, self-assembly can be altered by the inclusion of various factors, including molecular functionalization, 12,13 charge separation, 14 and surface modification. 15 Self-assembly, along with the related fields of supramolecular chemistry and crystal engineering, has many practical applications including coatings, 16,17 nanoscale electronics, 18,19 and pharmaceuticals.…”

“…Molecular self-assembly is defined as the spontaneous process of bringing molecules together via noncovalent interactions to form highly organized structures without external direction. Micelle formation is a prototypical self-assembly process occurring in the natural world, as is the formation of the DNA double helix through complementary base pairing. , Structures engineered by controlled self-assembly can be simple, such as atoms forming into local islands on metal surfaces , or thiolate monolayers on gold surfaces, , with increasing complexity including multilayer structures , and host–guest composites. , Additionally, self-assembly can be altered by the inclusion of various factors, including molecular functionalization, , charge separation, and surface modification . Self-assembly, along with the related fields of supramolecular chemistry and crystal engineering, has many practical applications including coatings, , nanoscale electronics, , and pharmaceuticals. , …”