N-Arylated 3,5-Dihydro-4H-dinaphtho[2,1-c:1 ',2 '-e]azepines: Axially Chiral Donors with High Helical Twisting Powers for Nonplanar Push-Pull Chromophores
| Autor: | Alberta Ferrarini, Corinne Boudon, Gian Piero Spada, Fiammetta Ferroni, Jean-Paul Gisselbrecht, Samuel Jakob, Brian Frank, Paul Seiler, Silvia Pieraccini, Berta Camafort Blanco, François Diederich |
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| Přispěvatelé: | B. B. Frank, B. Camafort Blanco, S. Jakob, F. Ferroni, S. Pieraccini, A. Ferrarini, C. Boudon, J.-P. Gisselbrecht, P. Seiler, G. P. Spada, F. Diederich |
| Jazyk: | angličtina |
| Rok vydání: | 2009 |
| Předmět: |
Circular dichroism
Stereochemistry Chemistry Organic Chemistry intramolecular charge-transfer General Chemistry helical twisting power Chromophore surface chirality model chiral push-pull chromophores DFT calculations Catalysis Cycloaddition N-Arylated dinaphthazepines circular dichroism Crystallography Enantiopure drug Liquid crystal Axial chirality Intramolecular force axial chirality Chirality (chemistry) |
| Popis: | Axially chiral, N-arylated 3,5-dihydro-4H-dinaphtho[2,1-c:1',2'-e]azepines have been prepared by short synthetic protocols from enantiopure 1,1'-bi(2,2'-naphthol) (BINOL) and anilines. Alkynes substituted with two N-phenyldinaphthazepine donors readily undergo a formal [2+2] cycloaddition, followed by retro-electrocyclization, with tetracyanoethene (TCNE) to yield donor-substituted 1,1,4,4-tetracyanobuta-1,3-dienes (TCBDs) featuring intense intramolecular charge-transfer (CT) interactions. A dicyanovinyl derivative substituted with one N-phenyldinaphthazepine donor was obtained by a "one-pot" oxidation/Knoevenagel condensation from the corresponding propargylic alcohol. Comparative electrochemical, X-ray crystallographic, and UV/Vis studies show that the electron-donor qualities of N-phenyldinaphthazepine are similar to those of N,N-dimethylanilino residues. The circular dichroism (CD) spectrum of a push-pull chromophore incorporating the chiral donor moiety features Cotton effects of exceptional intensity. With their elongated shape and the rigidity of the chiral N-aryldinaphthazepine donors, these chromophores are effective inducers of twist distortion in nematic liquid crystals (LCs). Thus, a series of the dinaphthazepine derivatives was used as dopants in the nematic LC E7 (Merck) and high helical twisting powers (beta) of the order of hundreds of microm(-1) were measured. Theoretical calculations were employed to elucidate the relation between the structure of the dopants and their helical twisting power. For the derivatives with two dinaphthazepine moieties, a strong dependence of the beta-values on the structure and conformation of the linker between them was found. |
| Databáze: | OpenAIRE |
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