Chirality, as an inherently geometric concept, is well understood at most length scales and is a principal attribute of objects and figures. Quantitative models predicting the efficacy of chirality transmission across length scales have only recently begun to emerge. We provide further proof-of-concept data and calculations for a modus operandi for nanoshape solutes featuring a chiral ligand shell in an achiral discotic nematic (ND) liquid crystal solvent, demonstrating that chirality transfer can be understood through remarkably simple geometric considerations. This mechanism is based on the product of a pseudoscalar chirality indicator and a geometric shape compatibility factor based on the 2D isoperimetric quotients for nanoshape solutes and ND molecule. The model is tested on an experimental set of precisely engineered gold nanoshapes, rods, prisms, and discs, that validates that shape commensurability between nanoscale solute and nematic solvent is a prerequisite for efficacious chirality transfer as determined by the helical twisting power of the nanoshapes in the induced chiral ND* phase. Thus, we predict that libraries of calculated and in-parallel acquired experimental data among related nanoshapes and even small organic molecules pave the way for predictive calculations of chirality transfer in nanoscale, macromolecular, biological, and small-molecule systems.

Herein, we present the fabrication of freestanding cellulose nanocrystal (CNC) films exhibiting blue, green, red, and, in combination, near-white right-handed CPL (RCPL) through covalent grafting of achiral fluorophores to CNCs via Steglich esterification. The weakly-twisted CNCs, hierarchically organized through evaporation-induced self-assembly, act as chiral scaffolds enforcing the supramolecular chirality. The ensuing composite CNC films display dye-specific photoluminescence with maximum negative luminescence dissymmetry ( g l u m ) values of -0.15, -0.16, and -0.11 for blue, green, and red emissive films, respectively, indicative of preferential right-handed emission. Morphological evaluation via scanning electron microscopy (SEM) reveals well-defined Bouligand arches, and studies by polarized optical microscopy (POM) fingerprint textures, each confirming the preservation of chiral nematic ordering across all emissive films. Notably, by integration of all three fluorescent dyes within the CNC matrix, near-white CPL was achieved by color mixing, as corroborated by CIE 1931 chromaticity analysis with | g l u m | values ranging from 0.05 to 0.10 over the visible spectral region, with ∼ 90% permanence of the fluorescence over a 12-h irradiation period. This approach establishes the basic framework for generating mechanically and thermally robust CPL-active, principally bio-renewable chiral CNC materials and optical elements for advanced displays, optoelectronic devices, and chiroptical sensing platforms.

Health risks affiliated with exposure to a wide variety of toxic gases and vapors are a certainty for first responders such as firefighters and HAZMAT team members but also for countless other professions from water purification and chemical manufacturing to the oil and gas industry, among others, and even the general public. Here the fabrication and testing of several prototypes for a novel toxic gas sensor platform based on ink-jet printed nematic liquid crystal patterns are described. These sensors require zero power to operate and are characterized by high sensitivity down to highly relevant ppm and ppb levels, fast response times on the order of seconds, improved durability, and an overall design that is highly customizable by the potential end user. The response times of these sensors exponentially decrease with toxic gas concentration, thereby establishing the toxic gas diffusivity dependence of their mode of action. Such prototypes for two particular toxic gases, chlorine, and phosgene, performing interference testing in high humidity and smoke conditions as well as field testing with active firefighters are demonstrated.

Filamentous viruses are a tunable platform for understanding the propagation of chirality across length scales, starting from the helical organization of major coat proteins on the virion surface to the liquid crystalline cholesteric phases formed in aqueous suspensions.

Self-assembled lamellar nano- and microfilaments formed by select types of bent-core molecules are prime examples of the interplay between molecular conformation and morphological chirality. Here, we demonstrate how the strategic placement of chiral centers at C-1 and/or C-3 in the terminal alkyloxy side chains, largely based on a priori calculations of molecular conformation, leads to the predictable formation of increasingly complex nano- and microfilament morphologies. Adding to the previously described diversity of twisted and writhed filament types, we here demonstrate and explain the formation and coexistence of flat nanoribbons, nanocylinders, or nano- as well as microfilaments where the morphology spontaneously changes along the filament long axis. For some these more exotic types of filament morphology, helical multilayer filaments suddenly unwind to form flat nanoribbons that also twist again under preservation (not perversion) of the helical twist sense. Moreover, the morphologies formed by this series of molecules now allows us to demonstrate the complete transformation from flat multilayer ribbons over microfilaments and helical-wrapped nanocylinders to helical nanofilaments depending on the number and position of chiral centers in the aliphatic side chains.

Organic chiral nanofilaments are part of an important class of nanoscale chiral materials that has recently been receiving significant attention largely due to their potential use in applications such as optics, photonics, metameterials, and potentially a range of medical as well as sensing applications. This review will focus on key examples of the formation of such nano- and micro-filaments based on carbon nanofibers, polymers, synthetic oligo- and polypeptides, self-assembled organic molecules, and one prominent class of liquid crystals. The most critical aspects discussed here are the underlying driving forces for chiral filament formation, potentially answering why specific sizes and shapes are formed, what molecular design strategies are working equally well or rather differently among these materials classes, and what uses and applications are driving research in this fascinating field of materials science.

The importance of and the difference between molecular versus structural core chirality of substances that form nanomaterials, and their ability to transmit and amplify their chirality to and within a surrounding condensed medium is yet to be exactly understood. Here we demonstrate that neat as well as disodium cromoglycate (DSCG) surface-modified cellulose nanocrystals (CNCs) with both molecular and morphological core chirality can induce homochirality in racemic nematic lyotropic chromonic liquid crystal (rac-N-LCLC) tactoids. In comparison to the parent chiral organic building blocks, D-glucose, endowed only with molecular chirality, both CNCs showed a superior chirality transfer ability. Here, particularly the structurally compatible DSCG-modified CNCs prove to be highly effective since the surface DSCG moieties can insert into the DSCG stacks that constitute the racemic tactoids. Overall, this presents a highly efficient pathway for chiral induction in an aqueous medium and thus for understanding the origins of biological homochirality in a suitable experimental system.

Graphical Abstract The Cover Feature illustrates the formation of homochiral nematic lyotropic chromonic liquid crystal tactoids formed by disodium cromoglycate in water by the addition of cromoglycate surface-modified cellulose nanocrystals (CNCs) as chiral solutes. Using CNCs with an inherently chiral core reveals that biorenewable chiral solutes can serve as suitably powerful and increasingly multipurpose chiral additives. More information can be found in the Research Article by Diana P. N. Gonçalves, Timothy Ogolla, and Torsten Hegmann.

In our continuing pursuit to generate, understand, and control the morphology of organic nanofilaments formed by molecules with a bent molecular shape, we here report on two bent-core molecules specifically designed to permit a phase or morphology change upon exposure to an applied electric field or irradiation with UV light. To trigger a response to an applied electric field, conformationally rigid chiral (S,S)-2,3-difluorooctyloxy side chains were introduced, and to cause a response to UV light, an azobenzene core was incorporated into one of the arms of the rigid bent core. The phase behavior as well as structure and morphology of the formed phases and nanofilaments were analyzed using differential scanning calorimetry, cross-polarized optical microscopy, circular dichroism spectropolarimetry, scanning and transmission electron microscopy, UV-vis spectrophotometry, as well as X-ray diffraction experiments. Both bent-core molecules were characterized by the coexistence of two nanoscale morphologies, specifically helical nanofilaments (HNFs) and layered nanocylinders, prior to exposure to an external stimulus and independent of the cooling rate from the isotropic liquid. The application of an electric field triggers the disappearance of crystalline nanofilaments and instead leads to the formation of a tilted smectic liquid crystal phase for the material featuring chiral difluorinated side chains, whereas irradiation with UV light results in the disappearance of the nanocylinders and the sole formation of HNFs for the azobenzene-containing material. Combined results of this experimental study reveal that in addition to controlling the rate of cooling, applied electric fields and UV irradiation can be used to expand the toolkit for structural and morphological control of suitably designed bent-core molecule-based structures at the nanoscale.

Cellulose nanocrystals, surface-decorated with azobenzenes, are introduced as chiral solutes with molecular and morphological chirality and bestowed with the ability to photoswitch the helical pitch of induced chiral nematic liquid crystal phases.

Chirality, as a concept, is well understood at most length scales. However, quantitative models predicting the efficacy of the transmission of chirality across length scales are lacking. We propose here a modus operandi for a chiral nanoshape solute in an achiral nematic liquid crystal host showing that that chirality transfer may be understood by unusually simple geometric considerations. This mechanism is based on the product of a pseudoscalar chirality indicator and of a geometric shape compatibility factor based on the two-dimensional isoperimetric quotients for each nanoshape solute. The model is tested on an experimental set of precisely engineered gold nanoshapes. These libraries of calculated and in-parallel acquired experimental data among related nanoshapes pave the way for predictive calculations of chirality transfer in nanoscale, macromolecular, and biological systems, from designing chiral discriminators and enantioselective catalysts to developing chiral metamaterials and understanding nature's innate ability to transfer homochirality across length scales.

Aggregation-induced emission (AIE)-based circularly polarized luminescence (CPL) has been recognized as a promising pathway for developing chiroptical materials with high luminescence dissymmetry factors (|glum|). Here, we propose a method for the construction of a thermally tunable CPL-active system based on a supramolecular self-assembly approach that utilizes helical nano- or microfilament templates in conjunction with an AIE dye. The CPL properties of the ensuing ensembles are predominantly determined by the intrinsic geometric differences among the various filament templates such as their overall dimensions (width, height, and helical pitch) and the area fraction of the exposed aromatic segments or sublayers. The proposed mechanism is based on the collective data acquired by absorption, steady state and time-resolved fluorescence, absolute quantum yield, and CPL measurements. The highest |glum| value for the most promising dual-modulated helical nanofilament templates in the present series was further enhanced, reaching up to |glum| = 0.25 by confinement in the appropriate diameter of anodized aluminum oxide (AAO) nanochannels. It is envisioned that this methodology will afford new insights into the design of temperature-rate indicators or anti-counterfeiting tags using a combination of structural color by the nano- and microfilament templates and the AIE property of the guest dye.

This series of publications describes research rendering soft polyisobutylene (PIB)-based thermoplastic elastomers 3D printable by blending with rigid chemically compatible thermoplastics. The molecular structure, morphology, physical properties, and 3D printability of such blends have been systematically investigated. The authors' first report was concerned with the rendering of soft poly(styrene-b-isobutylene-b-styrene) (SIBS) 3D printable by blending with rigid polystyrene (PS). Here they report the macromolecular engineering of SIBS/polyphenylene oxide (PPO) blends for 3D printing. PPO, a rigid high-performance thermoplastic, is compatible with the hard PS block in SIBS; however, neither PPO nor SIBS can be directly 3D printed. The microphase-separated structures and physical properties of SIBS/PPO blends are systematically tuned by controlling blending ratios and molecular weights. Suitable composition ranges and desirable properties of SIBS/PPO blends for 3D printing are optimized. The morphology and properties of SIBS/PPO blends are characterized by an ensemble of techniques, including atomic force microscopy, small-angle X-ray scattering, and thermal and mechanical properties testing. The elucidation of processing-structure-property relationship of SIBS/PPO blends is essential for 3D printing and advanced manufacturing of high-performance polymer systems.

Nanoparticles serving as a multifunctional and multiaddressable dopant to modify the properties of liquid crystalline matrices are developed by combining cobalt ferrite nanocrystals with organic ligands featuring a robust photosensitive unit and a source of chirality from the natural pool. These nanoparticles provide a stable nanocomposite when dispersed in achiral liquid crystals, giving rise to chiral supramolecular structures that can respond to UV-light illumination, and, at the same time, the formed nanocomposite possesses strong magnetic response. We report on a nanocomposite that shows three additional functionalities (chirality and responsiveness to UV light and magnetic field) upon the introduction of a single dopant into achiral liquid crystals.

This perspective reports on recent progress toward the development of an approach toa prioripredict - both chirality “strength” and efficacy of chirality transfer from a chiral nanoshape solute to an achiral nematic environment.

Composites based on ε-caprolactone-d,l-lactide-based elastomer with cellulose nanocrystals (CNC) are investigated to understand how matching cells with appropriate mechanical environments can provide important insights into fundamental cell behaviors.

Nematic liquid crystals of achiral molecules or racemic mixtures of chiral ones form flat films when suspended in submillimeter size grids and submerged under water. Recently, it has been shown (Popov et al., 2017) that films of nematic liquid crystals doped with chiral molecules adopt biconvex lens shapes underwater. The curved shape together with degenerate planar anchoring leads to a radial variation of the optical axis along the plane of the film, providing a Pancharatnam-Berry-type phase lens that modifies geometric optical imaging. Here, we describe nematic liquid crystal microlenses formed by the addition of chiral nanoparticles. It is found that the helical twisting power of the nanoparticles, the key factor to form the lens, is about 400 μm-1, greater than that of the strongest molecular chiral dopants. We demonstrate imaging capabilities and measure the shape as well as the focal length of the chiral nanoparticle-doped liquid crystal lens. We show that measuring the shape of the lens allows one to calculate the helical pitch of the chiral nematic liquid crystal and thus determine the helical twisting power of the chiral ligand-capped nanoparticles. Such measurements require the use of only nanograms of chiral nanoparticles, which is 3 orders of magnitude less than that required by conventional techniques. Since NPs are sensitive to external stimuli such as light and electric and magnetic fields, the use of chiral NPs may allow the achievement of tunable optical properties for such microlens arrays.