Manipulation of Supramolecular Chirality in Bicontinuous Networks of Bent-Shaped Polycatenar Dimers.

Bicontinuous cubic liquid crystalline (LC) phases are of particular interest due their possible applications in electronic devices and special supramolecular chirality. Herein, we report the design and synthesis of first examples of achiral bent-shaped polycatenar dimers, capable of displaying mirror symmetry breaking in their cubic and isotropic liquid phases. The molecules have a taper-shaped 3,4,5-trialkoxybenzoate segment connected to rod-like building unit terminated with one terminal flexible chain.

Spectroscopic investigation on shuttlecock-shaped liquid crystalline trimers: Mesomorphic behaviour and its application in optical storage devices.

In this paper, we discuss the synthesis and characterization of 2,3,4-tris[-((4-(-cyanophenyl)diazenyl)phenoxy)alkyloxy]benzonitrile obtained by coupling 2,3,4-trihydroxy benzonitrile and ()-4-((4-((-bromoalkyl)oxy)phenyl)diazenyl)benzonitrile, pertain to shuttlecock shaped liquid crystals. The molecular structure was confirmed by NMR spectroscopic and elemental analyzer. The thermal behavior of the trimers was assessed using a polarizing optical microscope (POM) and differential scanning calorimetry (DSC).

Highly branched bolapolyphilic liquid crystals with a cubic A15 network at the triangle-square transition.

Rod-like bolapolyphiles with highly branched carbosilane-based side-chains self-assemble into several honeycomb structures if the oligo(-phenylene ethynylene) core is polyfluorinated, whereas for the non-fluorinated series an A15 type cubic network of rod-bundles was observed instead, suggesting a brand new pathway for the transition between triangular and square honeycomb phases.

Corrosion mitigation characteristics of some novel organoselenium thiourea derivatives for acid pickling of C1018 steel via experimental and theoretical study.

Two organoselenium thiourea derivatives, 1-(4-(methylselanyl)phenyl)-3-phenylthiourea (DS036) and 1-(4-(benzylselanyl)phenyl)-3-phenylthiourea (DS038) were produced and categorized using FTIR and NMR (H and C). The effectiveness of the above two compounds as C-steel corrosion inhibitors in molar HCl was evaluated using the potentiodynamic polarization (PD) and electrochemical impedance spectroscopy (EIS) techniques. PD findings indicate that DS036 and DS038 have mixed-type features.

Synthesis and in Silico Investigation of Organoselenium-Clubbed Schiff Bases as Potential M Inhibitors for the SARS-CoV-2 Replication.

Since the first report of the organoselenium compound, ebselen, as a potent inhibitor of the SARS-CoV-2 M main protease by Z. Jin et al. (Nature, 2020), different OSe analogs have been developed and evaluated for their anti-COVID-19 activities.

Hierarchical Macroporous PolyDCPD Composites from Surface-Modified Calcite-Stabilized High Internal Phase Emulsions.

High Internal Phase Emulsions (HIPEs) of dicyclopentadiene (DCPD) were prepared using mixtures of surface-modified calcite (Calcite) and a non-ionic surfactant. Twelve different emulsion formulations were created using an experimental design methodology. Three distinctive levels of the internal phase ratio, the amount of Calcite loading, and the surfactant were used to prepare the HIPEs.

Shear-induced birefringence in an optically isotropic cubic liquid crystalline phase.

We report an unusually strong flow-induced birefringence in an optically isotropic cubic phase occurring below the isotropic chiral conglomerate phase formed by a low-molecular-weight polycatenar mesogen. The transition into the birefringent state occurs thresholdless and the induced birefringence is comparable with that observed in polymeric systems. We suggest that the flow-induced deformation of the cubic structure is responsible for the strong rheo-optical response.

Unexpected kinetically controlled organoselenium-based isomaleimide: X-ray structure, hirshfeld surface analysis, 3D energy framework approach, and density functional theory calculation.

Reduction of 4,4'-diselanediyldianiline () followed by the reaction with bromo-4-(bromomethyl)benzene afforded the corresponding 4-((4-bromobenzyl)selanyl)aniline () in 85% yield. -Maleanilic acid was obtained in 94% yield via the reaction of selenoamine with toxilic anhydride. Subsequent dehydration of -maleanilic acid using acetic anhydride furnished the unexpected isomaleimide 5-((4-((4-bromophenyl)selanyl)phenyl)imino)furan-2(5H)-one () instead of the maleimide .

Switching Chirophilic Self-assembly: From meso-structures to Conglomerates in Liquid and Liquid Crystalline Network Phases of Achiral Polycatenar Compounds.

Spontaneous generation of chirality from achiral molecules is a contemporary research topic with numerous implications for technological applications and for the understanding of the development of homogeneous chirality in biosystems. Herein, a series of azobenzene based rod-like molecules with an 3,4,5-trialkylated end and a single n-alkyl chain involving 5 to 20 aliphatic carbons at the opposite end is reported. Depending on the chain length and temperature these achiral molecules self-assemble into a series of liquid and liquid crystalline (LC) helical network phases.

Supramolecular -Trick: Ambidextrous Mirror Symmetry Breaking in a Liquid Crystalline Network with Tetragonal Symmetry.

Bicontinuous and multicontinuous network phases are among nature's most complex structures in soft matter systems. Here, a chiral bicontinuous tetragonal phase is reported as a new stable liquid crystalline intermediate phase at the transition between two cubic phases, the achiral double gyroid and the chiral triple network cubic phase with an 23 space group, both formed by dynamic networks of helices. The mirror symmetry of the double gyroid, representing a -structure of two enantiomorphic networks, is broken at the transition to this tetragonal phase by retaining uniform helicity only along one network while losing it along the other one.

Mirror Symmetry Breaking and Network Formation in Achiral Polycatenars with Thioether Tail.

Mirror symmetry breaking in systems composed of achiral molecules is of importance for the design of functional materials for technological applications as well as for the understanding of the mechanisms of spontaneous emergence of chirality. Herein, we report the design and molecular self-assembly of two series of rod-like achiral polycatenar molecules derived from a π-conjugated 5,5'-diphenyl-2,2'-bithiophene core with a fork-like triple alkoxylated end and a variable single alkylthio chain at the other end. In both series of liquid crystalline materials, differing in the chain length at the trialkoxylated end, helical self-assembly of the π-conjugated rods in networks occurs, leading to wide temperature ranges (>200 K) of bicontinuous cubic network phases, in some cases being stable even around ambient temperatures.

Molecular Packing in Double Gyroid Cubic Phases Revealed via Resonant Soft X-Ray Scattering.

The bicontinuous double gyroid phase is one of the nature's most symmetric and complex structures, the electron density map of which was established long ago. By utilizing small-angle x-ray scattering, resonant soft x-ray scattering at the carbon K edge and model-dependent tensor-based scattering theory, we have not only elucidated morphology but also identified molecular packing in the double gyroid phases formed by molecules with different shapes, i.e.

Stereochemical Rules Govern the Soft Self-Assembly of Achiral Compounds: Understanding the Heliconical Liquid-Crystalline Phases of Bent-Core Mesogens.

A series of bent-shaped 4-cyanoresorcinol bisterephthalates is reported. Some of these achiral compounds spontaneously form a short-pitch heliconical lamellar liquid-crystalline phase with incommensurate 3-layer pitch and the helix axis parallel to the layer normal. It is observed at the paraelectric-(anti)ferroelectric transition, if it coincides with the transition from random to uniform tilt and with the transition from anticlinic to synclinic tilt correlation of the molecules in the layers of the developing tilted smectic phase.

Polar Order, Mirror Symmetry Breaking, and Photoswitching of Chirality and Polarity in Functional Bent-Core Mesogens.

In recent years, liquid crystals (LCs) responding to light or electrical fields have gained significant importance as multifunctional materials. Herein, two new series of photoswitchable bent-core liquid crystals (BCLCs) derived from 4-cyanoresorcinol as the central core connected to an azobenzene based wing and a phenyl benzoate wing are reported. The self-assembly of these molecules was characterized by differential scanning calorimetry (DSC), polarizing light microscopy (POM), electro-optical, dielectric, second harmonic generation (SHG) studies, and XRD.

Isothermal Chirality Switching in Liquid-Crystalline Azobenzene Compounds with Non-Polarized Light.

Spontaneous mirror-symmetry breaking is a fundamental process for development of chirality in natural and in artificial self-assembled systems. A series of triple chain azobenzene based rod-like compounds is investigated that show mirror-symmetry breaking in an isotropic liquid occurring adjacent to a lamellar LC phase. The transition between the lamellar phase and the symmetry-broken liquid is affected by trans-cis photoisomerization, which allows a fast and reversible photoinduced switching between chiral and achiral states with non-polarized light.

Development of Polar Order by Liquid-Crystal Self-Assembly of Weakly Bent Molecules.

Organic ferroelectrics are of growing importance for multifunctional materials. Here we provide an understanding of the distinct stages of the development of sterically induced polar order in liquid-crystalline (LC) soft matter. Three series of weakly bent molecules derived from 4-cyanoresorcinol as the bent core unit with laterally fluorinated azobenzene wings have been synthesized, and the effects of the position of fluorine substitution, alkyl-chain length, and temperature on the LC self-assembly and polar order were studied.

Emergence of polar order and tilt in terephthalate based bent-core liquid crystals.

A new bent-core liquid crystalline material consisting of a 4-cyanoresorcinol unit with two terephthalate based rod-like wings and terminated by two short alkyl chains was synthesized. Its liquid crystalline (LC) self-assembly and the development of polar order in the LC phases were investigated. The polar order is characterised using second harmonic generation and dielectric spectroscopy techniques in addition to XRD and DSC characterisations of the mesophase structure and investigation of freely suspended films.

Mirror symmetry breaking in cubic phases and isotropic liquids driven by hydrogen bonding.

Achiral supramolecular hydrogen bonded complexes between rod-like 4-(4-alkoxyphenylazo)pyridines and a taper shaped 4-substituted benzoic acid form achiral (Ia3[combining macron]d) and chiral "Im3[combining macron]m-type" bicontinuous cubic (I432) phases and a chiral isotropic liquid mesophase (Iso*). The chiral phases, resulting from spontaneous mirror symmetry breaking, represent conglomerates of macroscopic chiral domains eventually leading to uniform chirality.

Helical Nano-crystallite (HNC) Phases: Chirality Synchronization of Achiral Bent-Core Mesogens in a New Type of Dark Conglomerates.

Spontaneous generation of macroscopic homochirality in soft matter systems by self-assembly of exclusively achiral molecules under achiral conditions is a challenging task with relevance for fundamental scientific research and technological applications. Dark conglomerate phases (DC phases), being optically isotropic mesophases composed of conglomerates of macroscopic chiral domains and formed by some non-chiral bent-core mesogens, represent such a case. Here we report two new series of non-symmetric bent-core molecules capable of forming a new type of mirror symmetry broken DC phases.

Development of Polar Order in the Liquid Crystal Phases of a 4-Cyanoresorcinol-Based Bent-Core Mesogen with Fluorinated Azobenzene Wings.

A bent-core mesogen consisting of a 4-cyanoresorcinol unit as the central core and laterally fluorinated azobenzene wings forms four different smectic LC phase structures in the sequence SmA-SmCs -SmCs PAR -M, all involving polar SmCs PS domains with growing coherence length of tilt and polar order on decreasing temperature. The SmA phase is a cluster-type de Vries phase with randomized tilt and polar direction; in the paraelectric SmCs phase the tilt becomes uniform, although polar order is still short-range. Increasing polar correlation leads to a new tilted and randomized polar smectic phase with antipolar correlation between the domains (SmCs PAR ) which then transforms into a viscous polar mesophase M.

Spontaneous Mirror-Symmetry Breaking in Isotropic Liquid Phases of Photoisomerizable Achiral Molecules.

Spontaneous mirror-symmetry breaking is of fundamental importance in science as it contributes to the development of chiral superstructures and new materials and has a major impact on the discussion around the emergence of uniform chirality in biological systems. Herein we report chirality synchronization, leading to spontaneous chiral conglomerate formation in isotropic liquids of achiral and photoisomerizable azobenzene-based rod-like molecules. The position of fluorine substituents at the aromatic core is found to have a significant effect on the stability and the temperature range of these chiral liquids.

Dark conglomerate phases of azobenzene derived bent-core mesogens - relationships between the molecular structure and mirror symmetry breaking in soft matter.

New 4-bromoresorcinol based bent-core molecules with peripheral fluoro substituted azobenzene wings have been synthesized and the liquid crystalline self-assembly was investigated by differential scanning calorimetry (DSC), optical polarizing microscopy (POM), electro-optic studies and X-ray diffraction (XRD). A new type of optically isotropic mesophase composed of chiral domains with opposite handedness (dark conglomerate phases, DC phases) is observed, which for some homologues with medium alkyl chain length is stable down to ambient temperature. It is proposed that these DC phases are formed by helical twisted nano-domains of limited size and composed of the crystallized aromatic cores which are separated by the disordered alkyl chains.

Development of polar order and tilt in lamellar liquid crystalline phases of a bent-core mesogen.

A new bent-core mesogen combining a 4-cyanoresorcinol unit with two terephthalate based rod-like wings and terminated by two long alkyl chains, was synthesized and investigated by DSC, XRD, optical, electrooptical and dielectric methods. A series of liquid crystalline phases in the unique sequence SmA-SmA(P)-SmCPR-(M1/SmCPα)-SmCsPA-SmCPA-SmCaPA, mainly distinguished by the degree and mode of correlation of tilt and polar order, was observed. The development of polar order is associated with the emergence of a small tilt (<10°).

A new room temperature dark conglomerate mesophase formed by bent-core molecules combining 4-iodoresorcinol with azobenzene units.

The first bent-core molecules comprising 4-iodoresorcinol as the central core unit and incorporating azobenzene units have been synthesized. A new type of dark conglomerate phase (DC phase) is observed, which remains over a wide temperature range down to room temperature without crystallization.

A liquid crystalline phase with uniform tilt, local polar order and capability of symmetry breaking.

A new liquid crystalline (LC) phase with uniform tilt, local polar order and capability of symmetry breaking is found for a bent-core mesogen combining a 4-cyanoresorcinol unit with two azobenzene wings. The combination of local polar order and long range synclinic tilt in this SmC(s)P(R) phase leads, under special conditions, to macroscopic domains with opposite chirality, though the molecules themselves are achiral.