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The use of the biphasic isotropic/nematic region in a bisperylene imide-based lyotropic liquid crystal system allows the extraction of proton-carbon 1 DCH residual dipolar couplings in aqueous solution from a single F1-coupled HSQC experiment. The method was successfully applied to the RDC-based conformational analysis of sucrose.

Transfer of chirality from an adsorbed molecule to a metal nanoparticle surface, and from the resulting chiral nanoparticle to its surroundings, depends on numerous factors - structure of the adsorbed molecule, its size and shape, and its interactions with its specific environment - but is often difficult to understand and even more difficult to measure, visualize, and quantify. We examine if chirality at the nanoscale (i.e. in gold nanoparticles capped with chiral ligand molecules) is uniquely able to generate more intense responses than their organic chiral counterparts in soft condensed matter utilizing lyotropic chromonic liquid crystals (LCLCs) forming the nematic phase. As a powerful manifestation of nanoscale chiral amplification, we show that L-cysteine capped gold nanoparticles induce a tighter chiral twist within, and similar among, stacks of nematic LCLCs with several orders of magnitude fewer chiral L- cysteine ligands in comparison to the free molecular L-amino acid.

Composites of DNA origami nanostructures dispersed in a lyotropic chromonic liquid crystal are studied by polarizing optical microscopy. The homogeneous aqueous dispersions can be uniformly aligned by confinement between two glass substrates, either parallel to the substrates owing to uniaxial rubbing or perpendicular to the substrates using ozonized graphene layers. These opportunities of uniform alignment may pave the way for tailored anisometric plasmonic DNA nanostructures to photonic materials. In addition, a decorated texture with nonuniform orientation is observed on substrates coated with pristine graphene. When the water is allowed to evaporate slowly, microscopic crystal needles appear, which are aligned along the local orientation of the director. This decoration method can be used for studying the local orientational order and the defects in chromonic liquid crystals.

This study demonstrates that the bulk alignment of chromonic aggregates can be achieved during the swelling of hydrogels. Swelling of an ionic hydrogel immersed in an aqueous solution of disodium cromoglycate reorients the chromonic aggregates, and millimeter-thick optically anisotropic hydrogels are obtained. These anisotropic hydrogels contain the chromonic aggregates at a condensed concentration as high as in the columnar phase of a normal chromonic aqueous solution, although the X-ray diffraction results show much less stacking order and orientational order of the aggregates. Furthermore, anisotropic mechanical properties of the hydrogels are observed due to the anisotropic alignment of the chromonic aggregates.

Liquid crystals (LCs) represent a challenging group of materials for direct transmission electron microscopy (TEM) studies due to the complications in specimen preparation and the severe radiation damage. In this paper, we summarize a series of specimen preparation methods, including thin film and cryo-sectioning approaches, as a comprehensive toolset enabling high-resolution direct cryo-TEM observation of a broad range of LCs. We also present comparative analysis using cryo-TEM and replica freeze-fracture TEM on both thermotropic and lyotropic LCs. In addition to the revisits of previous practices, some new concepts are introduced, e.g., suspended thermotropic LC thin films, combined high-pressure freezing and cryo-sectioning of lyotropic LCs, and the complementary applications of direct TEM and indirect replica TEM techniques. The significance of subnanometer resolution cryo-TEM observation is demonstrated in a few important issues in LC studies, including providing direct evidences for the existence of nanoscale smectic domains in nematic bent-core thermotropic LCs, comprehensive understanding of the twist-bend nematic phase, and probing the packing of columnar aggregates in lyotropic chromonic LCs. Direct TEM observation opens ways to a variety of TEM techniques, suggesting that TEM (replica, cryo, and in situ techniques), in general, may be a promising part of the solution to the lack of effective structural probe at the molecular scale in LC studies.

We investigate the effect of monoatomic salts on the molecular dynamics in the nematic and isotropic phases formed by the chromonic liquid crystal Edicol Sunset Yellow. The study was carried out using proton nuclear magnetic resonance relaxometry. To analyse the effect of incorporation of additional sodium chloride or lithium chloride on the solutions’ molecular dynamics, the spin-lattice relaxation time was measured for Larmor frequencies between 10kHz and 100MHz. In the nematic phase, the presence of additional sodium or lithium ions seems to contribute to an increase of the rotations/reorientations correlation times in comparison with the mixture without extra ions. The collective motions detected by proton NMR relaxometry are associated with collective fluctuations of molecules within the stacks in the nematic phase and with order parameter fluctuations in the isotropic phase. Copyright © 2014 John Wiley & Sons, Ltd.

Chromonic liquid crystals (CLCs) have drawn attention for applications to organic electronics and optical films as well as biological materials. Understanding the alignment mechanism of CLCs is important for those applications. Using a polarized transmission optical microscope, we observe the optical texture, dichroism, and birefringence of CLC films of sunset yellow (SSY) confined by polyamide (nylon) films that are rubbed with a brush. The films align with the stacks of SSY molecules oriented, surprisingly, perpendicular to the rubbing direction. We propose that this alignment is stabilized by molecular interaction between the stretched nylon chains and molecular grooves of the SSY stacks rather than elastic energy of the CLCs due to surface topography induced by the rubbing.

In this review we have collated various supramolecular designs, all surrounding H-bonding among well-known functional groups (peptides, nucleic acids, amides, ureas, carboxylic acids, pyridine-hydroxyls, urethanes, imides and others), to dictate self-assembly of naphthalenediimide (NDI) π-systems (both small molecules and polymeric building blocks) that exhibit several exciting features including strong propensity for π–π interactions, π-acidity, excellent n-type semiconductivity, CT-complexation, ion–π interactions, ring-substitution dependent redox properties and photophysical properties. This article reveals that H-bonding can indeed serve as a very powerful and versatile tool to programmed self-assembly of a single or multiple dye system producing a wide range of tailored soft materials, including fibrillar gels, chromonic mesophases, foldamers, nanotubes, vesicles, reverse micelles and polymersomes, both in water and organic medium with distinct photophysical properties, charge transport properties, conductivity properties and functional group displays that are highly relevant in the fields of biology and organic electronics.

Soft matter with a hard core: Through PtII⋅⋅⋅PtII and hydrophobic interactions, planar organoplatinum(II) cations with chloride or sulfate as counterions self‐organize themselves in water into red‐emissive, chromonic, and viscoelastic mesophases from which aligned films and discrete uniaxial microfibers with cofacial molecular orientations can be readily prepared.

Lyotropic chromonic liquid crystals have great potential in both biosensing and optical devices due to their biocompatible nature and strong optical characteristics. These applications, however, demand a homogeneous and stable alignment on anisotropic surfaces, a challenge that, so far, has not been solved adequately. In this work, it is shown how to drastically increase the quality of in-plane alignment and stability of these liquid crystals on conventional rubbed polyimide substrates by the addition of a small amount of a nonionic surfactant. Samples with surfactant show excellent alignment that is stable for months, while control samples without surfactant show much poorer alignment that further deteriorates in days. Also, well-aligned dry films of chromonics can be prepared following this approach. It is demonstrated how to obtain high-quality alignment by controlling the concentration and the nature of the surfactant, in particular its molecular structure and hydrophilic/lipophilic balance (HLB value) and other critical parameters are discussed. It is believed that this approach may very well be essential for advancing the applicability of these water-based, biocompatible, and often highly dichroic materials for a wide range of uses.

Controlling supramolecular self-assembly in water-based solutions is an important problem of interdisciplinary character that impacts the development of many functional materials and systems. Significant progress in aqueous self-assembly and templating has been demonstrated by using lyotropic chromonic liquid crystals (LCLCs) as these materials show spontaneous orientational order caused by unidirectional stacking of plank-like molecules into elongated aggregates. In this work, it is demonstrated that the alignment direction of chromonic assemblies can be patterned into complex spatially-varying structures with very high micrometer-scale precision. The approach uses photoalignment with light beams that exhibit a spatially-varying direction of light polarization. The state of polarization is imprinted into a layer of photosensitive dye that is protected against dissolution into the LCLC by a liquid crystalline polymer layer. The demonstrated level of control over the spatial orientation of LCLC opens opportunities for engineering materials and devices for optical and biological applications.

Chromonic systems are lyotropic mesophases formed by soluble aromatic compounds. The basic structural units in these systems are stacks of molecules (rather than individual molecules or micellar assemblies). There are two common chromonic phases: a more dilute phase consisting of a nematic array of columns (the N phase) and a more concentrated phase in which the columns lie in a hexagonal array (the M phase). Chromonic phases are formed by a range of compounds, including drugs, dyes and nucleic acids, typically with three or four fused aromatic rings. They have distinctive optical textures and characteristic multi-peritectic phase diagrams (in contrast to the multi-eutectic phase diagrams of conventional amphiphiles). Many commercial dyes have proved to be chromonic, but the ability to form liquid crystalline phases has been incidental to their use. However, recent studies have shown that the combination of self-ordering, ease of alignment, sensitivity to changing conditions and additives, coupled with th...

LCLCs are com-posed of plank-like molecules with polyaromatic central core and hydrophilic ionic groups at the periphery. Because of the hydrophobic nature of the aromatic central core and the hydrophilic periphery, the molecules assemble into stacks with degenerated molecular orientation in the molecular plane to form chromonic nematic (N) phase. In the N phase, the columnar aggregates align parallel to each other but show no long-range positional correlations. The variety of possible geometries of aggregations is enriched by the fact that the molecular planes can adopt different orientations with respect to the axis of the aggregates. Applications of chromonic liquid crystals are relatively unexplored. Potential applications reported for chromonic liquid crystals include the fabrication of light-harvesting devices

Chromonic liquid crystals (or chromonics) are formed by the self-organization of aromatic compounds with ionic or hydrophilic groups in aqueous solutions. This review summarizes the research on chromonic liquid crystals in the last two decades. The research embraced the studies of commercially available chromonic dyes and drugs, the syntheses and investigations of molecularly designed mesogens, the invention of novel processes for aligning chromonic liquid crystals, and the development of new applications as functional materials and biosensors.