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.
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.
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.
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).
Model guest: A guest anthraquinone dye that aligns within a nematic liquid crystal host is modelled by a combined computational approach. DFT calculations give the alignment of the transition dipole moment within the dye, and fully atomistic MD simulations model the alignment of the dye within the host.
Softening nanocrystalline gold: An efficient method to control the spatial arrangement of liquid crystalline gold nanoparticles was developed by changing the composition of the mesogenic grafting layer. Structural studies showed that the organic sublayer is more dense with increasing average ligand number, thereby separating the nanoparticles in the liquid crystalline phases, which changes the parameters of these phases (see figure).
Putting order into ionic liquids: Ionic liquid (IL)-based nonaqueous lyotropic liquid crystals (LLCs) exhibit extraordinarily high extraction capacity, excellent separation selectivity, and easy recycling. The introduction of self-assembled nanostructures into IL systems is an efficient way to enhance the recognition ability for H-bond donor molecules. The IL-based LLCs successfully combine the unique properties of ILs and LCs and provide a new platform for high-performance separation.
Crystals from stars: A new supramolecular synthon, based on tris(triazolyl)triazine (see figure), can interact through hydrogen bonds with benzoic acids and self-organize in columns.
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.