119984-87-1Relevant articles and documents
Development of helical aromatic amide foldamers with a diphenylacetylene backbone
Azumaya, Isao,Kagechika, Hiroyuki,Masu, Hyuma,Mori, Hirotoshi,Tanatani, Aya,Urushibara, Ko,Yamada, Tatsunori,Yokoyama, Akihiro,Yokozawa, Tsutomu
, p. 2019 - 2039 (2020)
We designed and synthesized aromatic polyamides with a diphenylacetylene backbone, α-DPA and β-DPA, bearing (S)-α-and (S)-β-methyl-substituted triethyleneglycol (TEG) side chains, respectively, and examined their conformations in solution. Both polymers exhibit strong, solvent polarity-dependent circular dichroism spectra, which indicated that they take helical conformations in low-polarity solvents. The spectra were mirror images, depending on the chiral position of the side chains. Thus, the polyamide α-DPA bearing (S)-α-methyl-substituted TEG groups takes a left-handed helical conformation, while the polyamide β-DPA with (S)-β-methyl-substituted TEG groups takes a right-handed helical conformation. The difference in the screw sense of α-DPA and β-DPA would be caused by the steric interaction between the main chain and the side chain, as observed in poly(p-benzamide) possessing (S)-β-methyl-substituted TEG side chains (β-PA) because the large cavity of the helical structure of DPA would disturb the solvophobically induced helical folding. Detailed conformational analyses of the oligoamides 6-12 with β-methyl-substituted TEG groups were conducted. Theoretical calculations indicated that the oligoamides with β-methyl-substituted TEG groups exist in a helical conformation with a cavity of 7 ? in diameter. The 1H NMR spectra of the oligomers revealed interactions with small anions such as chloride and acetate anions and with pyridinium cations.
The electronic structure and second-order nonlinear optical properties of donor-acceptor acetylenes: A detailed investigation of structure-property relationships
Stiegman,Graham, Eva,Perry, Kelly J.,Khundkar, Lutfur R.,Cheng,Perry, Joseph W.
, p. 7658 - 7666 (2007/10/02)
A series of donor-acceptor acetylene compounds was synthesized in which systematic in both the conjugation length and the donor-acceptor strength were made. The effect of these structural changes on the spectrcscopic electronic proprties of the molecules
