Front Cover: Multiply Twisted Chiral Macrocycles Clamped by Tethered Binaphthyls Exhibiting High Circularly Polarized Luminescence Brightness (Chem. Eur. J. 59/2022)

Abstract

Three kinds of chiral cyclic compounds and their mirror‐image isomers are described. The cover was created by using a “kaleidoscope” motif to project the three pairs of enantiomers in the central hexagon. The kaleidoscope is an optical device invented in the 19th century as a result of experiments on polarized light; the word “kaleidoscope”, derived from the Greek kalos “beautiful”, was used to represent the beautiful and circularly polarized luminescent (CPL) molecules. More information can be found in the Research Article by M. Hasegawa, Y. Mazaki, and co‐workers (DOI: 10.1002/chem.202202218).

Synthesis and Chiroptical Properties of Binaphthyl‐Hinged [5]Helicenes

“…The workup and purification procedures were performed using reagent‐grade solvents in air. ( R )/( S )‐( 2 ) was prepared from 7‐bromo‐2‐naphthol according to our previous study [32] . p ‐Xylylenebis(triphenylphosphonium) bromide was prepared according to a literature procedure [38] .…”

“…(R)/(S)-( 2) was prepared from 7-bromo-2-naphthol according to our previous study. [32] p-Xylylenebis(triphenylphosphonium) bromide was prepared according to a literature procedure. [38] LiOEt was prepared by reacting Li with EtOH in a glove box (under Ar) and used immediately.…”

“…Recently, we reported that a cyclic dimer composed of binaphthyl groups exhibited high | g lum | values in the CPL spectra ( D in Figure 1a). [31] Particularly, the amplification in the rigid binaphthyls tethered by ethylenedioxy was more pronounced [32] . The suppression of structural relaxation by rigid binaphthyl amplifies the chiroptical properties with C 2 symmetry in the excited state.…”

“…[31] Particularly, the amplification in the rigid binaphthyls tethered by ethylenedioxy was more pronounced. [32] The suppression of structural relaxation by rigid binaphthyl amplifies the chiroptical properties with C 2 symmetry in the excited state. In that context, we designed the cyclic [5]helicene derivatives 1 a and 1 b using chiral 1,1'-binaphthyl as a linker for configurational stabilization.…”

Synthesis of π‐Conjugated Chiral Aza/Boracyclophanes with a meta and para Substitution

“…[6] Despite substantial challenges arising from the synthesis, quite a few intriguing π-conjugated chiral macrocycles and fully fused nanobelts have been established by previous efforts, [7][8][9][10][11][12][13][14][15][16] including application of the concept of inherent planar chirality (with a uniform orientation of the aromatic moieties) [17][18][19][20][21][22][23][24] as well as incorporation of chiral subgroups into the ring skeletons. [25][26][27][28][29][30][31][32][33][34][35][36][37][38] The key advances of π-conjugated chiral macrocycles could also be associated with rapid progresses in chemistry of cycloparaphenylenes (CPPs) since the seminal synthesis in 2008 by Jasti et al [39][40][41][42][43][44][45][46] Not surprisingly thereafter, the design principles rooted in the CPP macrocyclic chemistry have been developed as one of the leading strategies to access carbon-based chiral macrocycles. [47][48][49]…”