Heterochiral recognition among functionalized heptahelicenes on noble metal surfaces

Abstract

No matter which heptahelicene derivative, all assemble into heterochiral zigzag chains on gold and silver(111) surfaces.

Unbalanced 2D Chiral Crystallization of Pentahelicene Propellers and Their Planarization into Nanographenes

“…A special, coverage‐dependent transition from homochiral clusters into racemic phases has been observed for [7]H and trioxa[11]helicene on Ag(100), [10] while a conversion from a solid solution into a racemate was reported for 5‐amino[6]helicene by alloying the Cu(100) surface with Sn [11] . Interestingly, functionalization of [7]H with cyano groups causes conglomerate formation on Cu(111), [12] while bromo‐, benzo‐ and S‐acetyl‐functionalized [7]H showed again the racemic zigzag motif on Ag and Au(111) surfaces [13] …”

“… [11] Interestingly, functionalization of [7]H with cyano groups causes conglomerate formation on Cu(111), [12] while bromo‐, benzo‐ and S‐acetyl‐functionalized [7]H showed again the racemic zigzag motif on Ag and Au(111) surfaces. [13] …”

“…[11] Interestingly, functionalization of [7]H with cyano groups causes conglomerate formation on Cu(111), [12] while bromo-, benzo-and Sacetyl-functionalized [7]H showed again the racemic zigzag motif on Ag and Au(111) surfaces. [13] Here it is shown that the 2D crystallization of the D 3symmetric tris(pentahelicene)benzene (T [5]H) leads to mirror domains on the Au(111) surface that have 33 % enantiomeric excess. That is, the enantiomeric M/P-ratio is 2 : 1 in one mirror domain and 1 : 2 in the other.…”

Double layer crystallization of heptahelicene on noble metal surfaces

“…A conglomerate‐to‐racemate transition was also observed on Ag(100) for [7]H. Enantiopure quadruplets at small coverage turned into racemic zigzag rows with increasing coverage 17 . Moreover, cyano‐functionalized [7]H forms a 2D conglomerate on Cu(111), 18 while bromo, benzo, and S ‐acetylthiolate functionalized [7]H formed zigzag racemate structures 19 . Finally, it seems noteworthy that the self‐assembly of 9,9′‐bis[7]H on copper and gold surfaces lead to diastereoselective separation into a racemate phase plus domains build up only by (M,P)‐ isomers 20,21 …”

On-Surface Mechanochemistry Synthesis of Non-Alternant Non-Benzenoid Aromatic Compounds Containing 4 to 8-Membered Rings

“…The conversion of a [7]helicene to planar coranulene derivative on Ag(111) surface (18) or the transformation of helical compounds with azuleno moieties to planar species with fulvaleno segments on Cu(001) surface (19) demonstrates such surface-induced reactions. Although several reports on the deposition of helical compounds on metal surfaces have been published (20)(21)(22), their further transformations have not been studied yet in detail and, thus, the above-mentioned studies (18,19) represent unique reports on the planarization of helical compounds in this potentially attractive but hitherto unexplored area.…”