Axially chiral, 3,5-dihydro-4H-dinaphtho[2,1-c:1′,2′-e]azepine (dinaphthazepine) and 1,1′-binaphthyl- 2,2′-disulfonimide (dinaphthosulfonimide) moieties were rigidly connected via N-p-phenylene linkers to photochemically (E)/(Z)-isomerisable 1,2-diethynylethene scaffolds. The chemical stability of the resulting systems was found to be critically related to the other substituents on the central π-conjugated scaffold. High helical twisting power (HTP), up to 315 μm−1, for the induction of a cholesteric liquidcrystalline phase through doping of a nematic phase was measured, resulting from the introduction of the chiral, mesogenic 1,1′-binaphthyl motifs. Single crystal X-ray analysis revealed that the phenylene spacer is in π-conjugation with the N-atom of the dinaphthazepine but not with the N-atom of the dinaphthosulfonimide moiety. This difference in orientation results in visible-transparency in the electronic absorption spectrum and higher (E)/(Z)-photoisomerisation quantum yields of the dinaphthosulfonimide-derived chiral dopants, as compared to the dinaphthazepine systems, which feature intramolecular charge-transfer absorption in the visible region.
Y-L. Wu, F. Ferroni, S. Pieraccini, W. B. Schweizer, B. B. Frank, G. P. Spada, et al. (2012). 1,2-DI(PHENYLETHYNYL)ETHENES WITH AXIALLY CHIRAL, 2,2’-BRIDGED 1,1’-BINAPHTYL SUBSTITUENTS: POTENT CHOLESTERIC LIQUID-CRYSTAL INDUCERS. ORGANIC & BIOMOLECULAR CHEMISTRY, 10, 8016-8026 [10.1039/c2ob25983d].
1,2-DI(PHENYLETHYNYL)ETHENES WITH AXIALLY CHIRAL, 2,2’-BRIDGED 1,1’-BINAPHTYL SUBSTITUENTS: POTENT CHOLESTERIC LIQUID-CRYSTAL INDUCERS
PIERACCINI, SILVIA;SPADA, GIAN PIERO;
2012
Abstract
Axially chiral, 3,5-dihydro-4H-dinaphtho[2,1-c:1′,2′-e]azepine (dinaphthazepine) and 1,1′-binaphthyl- 2,2′-disulfonimide (dinaphthosulfonimide) moieties were rigidly connected via N-p-phenylene linkers to photochemically (E)/(Z)-isomerisable 1,2-diethynylethene scaffolds. The chemical stability of the resulting systems was found to be critically related to the other substituents on the central π-conjugated scaffold. High helical twisting power (HTP), up to 315 μm−1, for the induction of a cholesteric liquidcrystalline phase through doping of a nematic phase was measured, resulting from the introduction of the chiral, mesogenic 1,1′-binaphthyl motifs. Single crystal X-ray analysis revealed that the phenylene spacer is in π-conjugation with the N-atom of the dinaphthazepine but not with the N-atom of the dinaphthosulfonimide moiety. This difference in orientation results in visible-transparency in the electronic absorption spectrum and higher (E)/(Z)-photoisomerisation quantum yields of the dinaphthosulfonimide-derived chiral dopants, as compared to the dinaphthazepine systems, which feature intramolecular charge-transfer absorption in the visible region.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
