Control over molecular motion using the cis–trans photoisomerization of the azo group

• Estíbaliz Merino and
• María Ribagorda

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

Ring-alkyl connecting group effect on mesogenic properties of p-carborane derivatives and their hydrocarbon analogues

• Aleksandra Jankowiak,
• Piotr Kaszynski,
• William R. Tilford,
• Kiminori Ohta,
• Adam Januszko,
• Takashi Nagamine and
• Yasuyuki Endo

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