Recent Progress in Chemistry of Multiple Helicenes

Abstract

The last decade has witnessed multiple helicenes arising as an interesting class of nonplanar polycyclic aromatics of inherent multihelicity. These molecules present esthetic structures and interesting properties not available to helicenes of single helicity. Herein an overview of multiple helicenes with respect to structures, stereochemical dynamics, synthesis, and applications is provided. Recently reported multiple helicenes are surveyed with an emphasis on molecular structures and stereochemistry of multiple carbohelicenes. After this survey, the synthesis of multiple helicenes through the Scholl reaction is discussed and recent applications of multiple helicenes in organic electronics are summarized. On the basis of these discussions, conclusions are reached on the current status of multiple helicenes and an outlook for this field is provided.

Symmetric, Unsymmetrical, and Asymmetric [7]‐, [10]‐, and [13]Helicenes

“…Electronic circular dichroism (ECD) spectroscopy (Figure 4) reveals the expected mirror image relationship between the two enantiomers of the [13]helicene (À)-25 and (+ +)-25.T he strongest ECD band (De =j 200 j m À1 cm) is observed in the UV region whereas the strongest ECD band (De =j 137 j Lmol À1 cm) in the visible part of the spectrum is located at 400 nm. Looking at the g-factor of 25, its maximum values is at 0.005, which is comparable to what has been reported for the carba [6]helicene. [27] In conclusion, as eries of azaoxa[n]helicenes have been presented.…”

“…This has been used in the construction of state‐of‐the‐art optical devices for the detection or emission of circularly polarized light . The past few years have witnessed a boom in the synthesis of helical aromatic systems containing expanded, elongated, or extended helicenes . These molecules typically display interesting optical properties and complex chiral behavior .…”

“…[4,5] Thep ast few years have witnessed ab oom in the synthesis of helical aromatic systems containing expanded, elongated, or extended helicenes. [6][7][8] These molecules typically display interesting optical properties and complex chiral behavior. [9] Theversatility of helicenes has been explored in the construction of cages for molecular recognition and in construction of photoswitches.…”

Tertiary Amines Differentiated from Primary and Secondary Amines by Active Ester‐Functionalized Hexabenzoperylene in Field Effect Transistors

“…The organic semiconductor used in this study is hexabenzoperylene( HBP), which is ad ouble [5]helicene. [11] As reported by us earlier,t he self-assembly of functionalized HBPs presents an unusualt ype of two-dimensional p-stacking, [12] which can accommodate avariety of functional groups without sacrificing p-p interactions in the solid state. As ar esult,f unctionalized HBPs provide ag eneral sensing platform, which, in ad evice integrating an OFET channel and am icrofluidic channel, has enabled highly sensitive and selective detection of fluoridei ons and streptavidin in water.…”

Improving Performance of Perovskite Solar Cells Using [7]Helicenes with Stable Partial Biradical Characters as the Hole‐Extraction Layers

“…Note that helicene is a class of material consisting of screw‐skeleton shaped polycyclic aromatics and helically fused aromatic rings, varying from monolayer to multilayer structures . Given this unique structure, helicenes have attracted lots of attention but the related applications as organic materials have been rarely explored …”