Liquid crytals (LCs) are probably the most exciting state of matter. They attract scientists across disciplines such as chemistry, physics, materials science, and engineering—theorists and experimentalists alike. These days, you can buy quite affordable LCD TV sets around the corner, but that's just one of the many things liquid crystals can do. The selection of recent research articles presented below illustrates the broad interest in this area of soft condensed matter.
J. W. Goodby, P. J. Collings, T. Kato, C. Tschierske, H. Gleeson,
Handbook of Liquid Crystals
2nd edition, Wiley-VCH, Weinheim, 2014.
Find all articles on liquid crystals in Wiley Online Library...
See the International Liquid Crystal Society's website.
Understanding the assembly and properties of helix still remains a great challenge. In this work, we report the first example of reversible switching of chiral columns formed by a helical cis-polyphenylacetylene (PPA) derivative P1, during a phase transition between two chiral columnar phases: the frustrated Φh3D-SL phase containing four chains at low temperature and a hexagonal columnar phase Φh at high temperature, accompanied by a conformational change simultaneously. The helix-helix transition occurring along the PPA backbone during the Φh3D-SL-Φh transition makes the uniaxially oriented P1 capable of elongating (132%) upon heating and contracting upon cooling reversibly and reproducibly, exhibiting the behavior of two-way shape actuator.
Er-Qiang Chen, Jun Wang, Xiao-Qing Liu, Xiang-Kui Ren, Ben Zhang, Shuang Yang, Yu Cao, Feng Liu, Bernard Lotz
Chem. Asian J., July 22, 2016, DOI: 10.1002/asia.201600879. Read article
Liquid crystal polymers that contain fluorinated azobenzenes and retain a photochemically generated shape for more than eight days are reported. To preserve photoactivated molecular deformation on the macroscopic scale, the thermal stability of the photoswitch, the cross-linking density in the polymer network, and the molecular orientations in the material have been optimized.
Supitchaya Iamsaard, Emmanuel Anger, Sarah Jane Aßhoff, Alexis Depauw, Stephen P. Fletcher, Nathalie Katsonis
Angew. Chem. Int. Ed., July 19, 2016, DOI: 10.1002/anie.201603579. Read article
All-optical deformation and recovery of complex 3D topographical features that can be addressed both remotely and selectively is demonstrated in blueprinted azobenzene-functionalized liquid crystalline elastomers. The photoinduced shape transformation strongly depends on the azobenzene concentration as well as the network structure (i.e., crosslink density).
Suk-kyun Ahn, Taylor H. Ware, Kyung Min Lee, Vincent P. Tondiglia, Timothy J. White
Adv. Funct. Mater., July 15, 2016, DOI: 10.1002/adfm.201601090. Read article
Puch and pull: The liquid-crystalline dyad ZnPc−C60 consists of hexadodecyl-substituted zinc(phthalocyanine) covalently linked through a flexible spacer to a fullerene. Its intriguing spectroscopic and electrochemical features have been investigated regarding electron transfer from the photoexcited, electron-donating ZnPc moiety to the electron-accepting C60 unit. The lifetime fo the charge-separated state was determined to be 2.2 ns (kCR=4.5×108 s−1) .
Marcus Lederer, Mine Ince, M. Victoria Martinez-Diaz, Tomas Torres, Dirk M. Guldi
ChemPlusChem, July 12, 2016, DOI: 10.1002/cplu.201600197. Read article
This paper elucidates the means to precisely control the morphology of electrospun liquid crystal/polymer fibers formed by phase separation. The relative humidity (RH), solution parameters (concentration, solvent) and the process parameter (feed-rate) have been varied systematically. We show that the morphology of the phase-separated liquid crystal can be continuously tuned from capsules to uniform fibers with systematic formation of beads-on-a-string (BOAS) structured fibers in the intermediate ranges. In all cases the polymer forms a sheath around a liquid crystal (LC) core. The width of the polymer sheath and the diameter of the LC core increase with increasing feed rates. This is similar to the results obtained by coaxial electrospinning. Because these fibers retain the responsive properties of liquid crystals and because of their large surface area they have potential applications as thermo, chemo and biosensors. Because the size and shape of the liquid crystal domains will have a profound effect on the performance of the fibers, our ability to precisely control morphology will be crucial in developing these applications.
Junren Wang, Antal Jákli, John Lawton West
ChemPhysChem, July 11, 2016, DOI: 10.1002/cphc.201600430. Read article
Bart Kahr, Alexander G. Shtukenberg
Isr. J. Chem., July 06, 2016, DOI: 10.1002/ijch.201600002. Read article
Polycatenar mesogens form columnar phases with the number of molecules in the column cross section. For some compounds, an electron density modulation along the columns is observed, which may lead to a new type of liquid crystal phase with three-dimensional positional order.
Joanna M. Wolska, Neha Topnani, Ewa Gorecka, Jozef Mieczkowski, Damian Pociecha
ChemPhysChem, June 15, 2016, DOI: 10.1002/cphc.201600330. Read article
Zwitterionic derivatives of the [closo-1-CB11H12]– anion form liquid-crystalline phases and improve the dielectric properties of nematic liquid-crystal materials.
Jacek Pecyna, Remigiusz Żurawiński, Piotr Kaszyński, Damian Pociecha, Piotr Zagórski, Serhii Pakhomov
Eur. J. Inorg. Chem., April 27, 2016, DOI: 10.1002/ejic.201600240. Read article.
Total recoil: A novel foldamer scaffold, in which p-phenyleneethynylene units are linked by chiral carbon atoms, is reported. In very dilute solutions, these oligomers are random coils. The hexamer and octamers form a hexagonal lyotropic liquid crystal in CH2Cl2 when the concentrations reach the critical values.
Yu Chen, Zhiqiang Zhao, Zheng Bian, Rizhe Jin, Chuanqing Kang, Xuepeng Qiu, Haiquan Guo, Zhijun Du, Lianxun Gao
ChemistryOpen, April 27, 2016, DOI: 10.1002/open.201600007. Read article
Versatile Suzuki cross-coupling reactions between arylboronic acids and triphenylenyl triflates generate a rich diversity of attractive functional discogens.
Ke-Qing Zhao, Yue Gao, Wen-Hao Yu, Ping Hu, Bi-Qin Wang, Benoît Heinrich, Bertrand Donnio
Eur. J. Org. Chem., April 13, 2016, DOI: 10.1002/ejoc.201600270. Read article.
A simple modular design was used to impart liquid-crystalline properties to iridium complexes without modification of their photophysical properties. Annealed films of the liquid-crystalline complexes display hole mobilities up to three orders of magnitude higher than parent iridium complex without mesogenic groups and are the highest values reported to date for iridium complexes (see figure).
Yafei Wang, Christopher P. Cabry, ManJun Xiao, Louise Male, Stephen J. Cowling, Duncan W. Bruce, Junwei Shi, Weiguo Zhu, Etienne Baranoff
Chem. Eur. J., December 22, 2015, DOI: 10.1002/chem.201504669. Read article.
Changing states: The cohesive free energy density concept (CFED) is applied to thermotropic cyanobiphenyl-based liquid crystals to establish predictive quantitative correlations between each antagonist segments of the amphiphilic molecules (flexible alkyl tail/rigid aromatic core) and their transition temperatures (solid→liquid crystalline/liquid crystalline→ isotropic liquid; see figure).
Thibault Dutronc, Emmanuel Terazzi, Laure Guénée, Kerry-Lee Buchwalder, Sébastien Floquet, Claude Piguet
Chem. Eur. J., December 14, 2015, DOI: 10.1002/chem.201503420. Read article.