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.
New Janus-like liquid crystals were synthesized by olefin cross-metathesis in the presence of the 2nd generation Grubbs catalyst. Linear, chiral, dendritic and nonmesomorphic olefins were used. Smectic C, smectic A, nematic and chiral phases were observed in agreement with the structure and nature of the mesogens.
Stack the deck: Cycloaramides, having a hydrogen-bond-constrained backbone and a well-defined inner cavity, exhibit rich liquid-crystalline mesomorphic properties. Exploitation of host–guest interactions between the cavity (blue/green discs) and alkylammonium salts (red) leads to distinct mesophase transitions from a lamellar to a hexagonal columnar phase, as shown by polarized optical microscopy.
Clustomesogens are metal atom clusters containing liquid-crystalline materials. They have been obtained by grafting neutral cyanobiphenyl- or cholesteryl-containing tailor-made dendritic mesomorphic triphenylphosphine oxide ligands on luminescent (M6Cli8)4+ octahedral cluster cores (M=Mo, W).
Crystal clear: Chiral dimers consisting of rod-like and cholesteric units form a chiral twist-bend nematic phase (NTB*; see picture). The compressibility of the NTB phase made of bent dimers was found to be as large as in smectic phases. Atomic force microscopy observations showed a periodicity of about 50 nm in the chiral NTB phase of bent dimers.
Stilbenoid superstars: Star mesogens that are sterically crowded at the core pack in an exceptional helical-columnar dimer phase (see Scheme, bottom left). Pyridyl groups in the interspace of the arms bind aromatic carboxylic acids and incrementally transform the dimer phase into a columnar phase of supermesogens (right).
The columnar self-assembly of a new class of 2-substituted N,N',N″-trialkylbenzene-1,3,5-tricarboxamides is reported. Hydrogen-bond-accepting substituents (e.g., alkoxy and alkynyloxy) were demonstrated to impair the columnar self-assembly process, whereas non-hydrogen-bond-accepting groups (e.g., bromine) strengthened the self-assembly process.
Out of the woods: Novel mesoporous and nanostructured materials can be generated by templating approaches based on cellulose-based liquid crystals derived from trees. This Review focuses on materials templated by cellulose nanocrystals, since their chiral nematic order allows their use in various optical applications such as optical filters, sensors, and optoelectronics.
Di- and tricationic organic salts combine the properties of corresponding monocationic salts with individual features due to the presence of different charged heads on the cation structures. This allows their use in different fields of application such as ionic liquid crystals and gel phases.
Riot of color: Alternate stacking of aromatic donor and acceptor building blocks by complementary and directional charge-transfer interactions produce versatile supramolecularly assembled materials including micelles, vesicles, nanotubes, fibrillar gels, folded polymers, cross-linked networks, and liquid-crystalline phases.