1361152-00-2Relevant academic research and scientific papers
Transformation of Thia[7]helicene to Aza[7]helicenes and [7]Helicene-like Compounds via Aromatic Metamorphosis
Hayasaka, Chikara,Nakano, Koji,Noguchi, Keiichi,Takase, Ko,Uematsu, Keisuke
, (2022/01/24)
[n]Helicenes with helically twisted structures have attracted increasing interest owing to their unique properties. Therefore, it has been an important issue to develop facile synthetic methodologies which allow access to a variety of [n]helicenes. Here we report the synthesis of [7]heli-cenes and [7]helicene-like compounds from the thia[7]helicene as a common starting material. Desulfurative dilithiation of the thia[7]helicene and the subsequent reaction with silicon and phos-phorus electrophiles afforded the silole-and phosphole-fused [7]helicene-like compounds, respec-tively. The cyclopentadiene-fused [7]helicene-like compound and the pyrrole-fused aza[7]helicenes were also successfully synthesized via twofold SNAr reactions of the thia[7]helicene S,S-dioxide with the carbon and nitrogen nucleophiles, respectively. The thia[7]helicene S,S-dioxide showed a slightly red-shifted absorption spectrum than the parent thia[7]helicene, which was well demonstrated by the theoretical calculations. The substituents on the silicon atom of silole-fused [7]heli-cene-like compounds have little impact on the longest absorption maximum. Such little effect of the substituents on absorption properties was also observed for cyclopentadiene-fused [7]helicene-like compounds and aza[7]helicenes and was well demonstrated by the theoretical calculations. The thia[7]helicene S,S-dioxide and the silole-fused [7]helicene-like compound exhibited bright blue emission, and the cyclopentadiene-fused [7]helicene-like compound and the aza[7]helicenes showed strong violet emission. Each single enantiomer of the aza[7]helicenes showed circularly-polarized luminescence with the dissymmetry factors of 4.2?4.4 × 10?3.
λ5-Phospha[7]helicenes: Synthesis, properties, and columnar aggregation with one-way chirality
Nakano, Koji,Oyama, Hiromi,Nishimura, Yoshio,Nakasako, Satoshi,Nozaki, Kyoko
, p. 695 - 699 (2012/02/14)
One-way street: A new family of λ5-phospha[7]helicenes which form one-dimensional columnar stacks in the solid state were synthesized (see scheme). Neighboring stacks have opposite dipole directions and, in the case of the racemic phosphole sul
