Chirality Transfer in 1D Self-Assemblies: Influence of H-Bonding vs Metal Coordination between Dicyano[7]helicene Enantiomers

Abstract

Chiral recognition as well as chirality transfer in supramolecular self-assembly and on-surface coordination is studied for the enantiopure 6,13-dicyano[7]helicene building block. It is remarkable that, with this helical molecule, both H-bonded chains and metal-coordinated chains can be formed on the same substrate, thereby allowing for a direct comparison of the chain bonding motifs and their effects on the self-assembly in experiment and theory. Conformational flexure and both adsorbate/adsorbent and intermolecular interactions can be identified as factors influencing the chiral recognition at the binding site. The observed H-bonded chains are chiral, however, the overall appearance of Cu-coordinated chains is no longer chiral. The study was performed via scanning tunneling microscopy, X-ray-photoelectron spectroscopy and density functional theory calculations. We show a significant influence of the molecular flexibility and the type of bonding motif on the chirality transfer in the 1D self-assembly.

Cyano‐Functionalized Triarylamines on Coinage Metal Surfaces: Interplay of Intermolecular and Molecule–Substrate Interactions

“…Such coordination bonds between cyano groups and native copper atoms were reported, for example, for cyano-functionalized porphyrin or helicene molecules on Cu(111). [14,15] Although the coordinated metal atom is generally not visible by STM, enhanced contrasti sv isible at the positiono ft he coordinated metal atom under specific tunnelling conditions, which is generally assumed to be as ignature for metal coordination ( Figure S8a in the Supporting Information). [21,28,29] X-ray photoelectron spectroscopy (XPS) measurements…”

“…[13] The study of molecular self-assembly of organic molecules functionalized with cyano groupsi sp articularly interesting, because the asymmetric charge distribution of the cyano group with the negatively polarized Na tom leads to the formation of al ocal internal dipole.T he cyano group can not only participate in H-bonding and dipolar coupling, but it can also efficiently coordinate to av ariety of metals. [14][15][16][17] Different molecular patternss uch as 0D clusters, 1D chains and 2D islands can be createdb yc hanging the number of cyano groups and/or their relative position, as was demonstrated for cyanofunctionalized porphyrin and polyphenylene derivatives. [4,14,18] Herein, we report on the self-assembly of the cyanofunctionalized planarized triarylamined erivative 4,4,8,8,12,12-hexamethyl-4H,8H,12H-benzo[1,9]quinolizino[3,4,5,6,7-defg]acridine-2,6,10-tricarbonitrile (1,S cheme1)o nc oinage metal (111) surfaces.…”

Programmed assembly of 4,2′:6′,4′′-terpyridine derivatives into porous, on-surface networks

“…[3][4][5][6][7][8] In contrast to the chelating ligand 2,2 0 :6 0 ,2 00 -terpyridine (2,2 0 :6 0 ,2 00 -tpy), 9 4,2 0 :6 0 ,4 00 -terpyridine (4,2 0 :6 0 ,4 00 -tpy) coordinates through only two N atoms and defines a divergent V-shaped building-block allowing control over the assembly of coordination polymers and networks. 2 However, the mechanism of their assembly (co-determined by the proximity of the surfaces and the presence of adatoms) remains sparsely investigated.…”

Synthetic Control of Photophysical Process and Circularly Polarized Luminescence of [5]Carbohelicene Derivatives Substituted by Maleimide Units

“…27 Helicenes are nonpolar polycyclic aromatic hydrocarbons (PAHs), which are formed by ortho-condensed benzene rings. They have been studied in various fields such as synthesis, [28][29][30] functional supramolecular architectures, [30][31][32][33][34][35] fluorescent sensors, 30,[36][37][38] and liquid-crystalline materials 30,[39][40][41][42] because of the characteristic molecular structures. They are also well-known to demonstrate unique chiroptical properties such as circular dichroism (CD) with anisotropy factor (g-value).…”