124767-57-3Relevant academic research and scientific papers
Photoinduced reversible gel-sol transitions of dicholesterol-linked azobenzene derivatives through breaking and reforming of van der Waals interactions
Wu, Yeping,Wu, Si,Tian, Xiujie,Wang, Xin,Wu, Wenxuan,Zou, Gang,Zhang, Qijin
scheme or table, p. 716 - 721 (2011/12/16)
A series of new symmetric dicholesterol-linked azobenzene gelators with different spacer lengths have been synthesized. The compounds with spacers of zero, two or six methylene units are denoted as DCAZO0, DCAZO2 and DCAZO6, respectively. A gelation test reveals that a subtle change in the length of the spacer can produce a dramatic change in the gelation behavior of the compounds. DCAZO2 obtains the minimum gelation concentration among the three gelators. For cyclopentanone gel of DCAZO2, the reversible gel-sol transitions by irradiation with UV and visible light are investigated by UV-vis absorption and circular dichroism (CD) spectra, SEM, TEM and XRD analyses. Upon UV irradiation of the gel, trans-cis photoisomerization of the azobenzene groups occurs, the change in molecular polarity leads to the breaking of van der Waals interactions, resulting in the gel-sol transition. The gel can be recovered by the reverse cis-trans photoisomerization after the exposure to visible light. SEM, TEM and XRD studies reveal that the gelator molecules self-assemble into one-dimensional fibers with diameters 50-100 nm in an anticlockwise direction, which further crossed-linked to form three-dimensional networks.
Synthesis and Properties of Liquid-Crystalline Polymers with Laterally and Terminally Linked Mesogenic Units
Roetz, U.,Lindau, J.,Weissflog, W.,Reinhold, G.,Unseld, W.,Kuschel, F.
, p. 185 - 194 (2007/10/02)
Within the class of dimesogenic liquid-crystalline polymers, series of new LC-polyesters with laterally and terminally linked mesogenic units were synthesized.The mesogenic moieties perpendicularly arranged to the main chain are endowed either with identical or with unequal wing groups.Depending on the wing group and the spacer length, the polyesters can form monotropic or enantiotropic nematic and smectic phases.These polymers were subjected to characterization studies using optical microscopy, differential scanning calorimetry and X-ray diffraction techniques.The phase behavior is compared with that of combined and cross-shaped polymeric mesogens.Keywords: structures of dimesogenic LC-polymers, combined LC-polymers, lateral fixation of mesogens, equal or unequal substituents.
