Beilstein J. Org. Chem.2012,8, 1071–1090, doi:10.3762/bjoc.8.119
: A central azobenzene, a rigid frame composed of oligo(phenylacetylenes), which in turn are anchored to azobenzene through para positions, and wheels based on fullerene C60 (azo-14) or p-carboranes (azo-15). Photoisomerization studies suggest that only the azobenzene system with p-carborane wheels
[124]. In the case of azo-p-carborane 15, irradiation at λ = 365 nm for 10 min leads to 24% of the cis isomer. The photochemical (λ > 495 nm, 5 min) or thermal (heating to 40 °C, 15 min) reisomerization recovers the initial state. After these preliminary results it remains to be demonstrated whether
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Graphical Abstract
Figure 1:
Photoisomerization process of azobenzene.
Beilstein J. Org. Chem.2009,5, No. 83, doi:10.3762/bjoc.5.83
University, 4-4-1, Komatsushima, Aoba-ku, Sendai 981-8558, Japan 10.3762/bjoc.5.83 Abstract The effect of the phenyl–alkyl connecting group on mesogenic properties of several series of isostructural compounds containing p-carborane (A and B), bicyclo[2.2.2]octane (C), and benzene (D) was investigated using
B) than for carbocyclic derivatives (C and D). Analysis indicates that this effect may have quadrupolar and conformational origin.
Keywords: p-carborane; liquid crystals; structure-property relationship; Introduction
During the past decade, we have been investigating mesogenic derivatives of p
of structurally related series of mesogens containing rings A–D (Figure 2), it became apparent that the benzene ring–alkyl chain connection has a distinctly different impact on phase stability in derivatives of p-carborane (A) than in their isostructural carbocycles. For instance, a larger
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Graphical Abstract
Figure 1:
The molecular structures of 1,12-dicarba-closo-dodecaborane (12-vertex p-carborane, A) and 1,10-dic...