LC Phase Research Articles

Preparation of molecularly imprinted polymers for warfarin and coumachlor by multi-step swelling and polymerization method and their imprinting effects

Monodisperse molecularly imprinted polymers (MIPs) for warfarin (WF) and coumachlor (CC), MIPWF and MIPCC, respectively, were prepared using 4-vinylpyridine (4-VPY) as a functional monomer and ethylene glycole dimethacrylate (EDMA) as a crosslinker by multi-step swelling and polymerization. Six kinds of MIPWF, MIPWF1 − MIPWF6, were prepared varying the concentrations of WF and 4-VPY, while maintaining the EDMA concentration constant, and their retention and molecular recognition properties were evaluated using a mixture of sodium phosphate buffer and acetonitrile as a mobile phase in LC. In addition to shape recognition, hydrogen bonding, ionic and hydrophobic interactions could affect the retention and molecular recognition of WF on MIPWF, and ionic interactions seem to govern the retention and molecular recognition of WF above mobile phase pH 6 associated with higher molar ratio of 4-VPY to EDMA. Furthermore, MIPCC was prepared under the same conditions with MIPWF6, which gave the highest imprinting factor for WF. WF could be recognized more strongly on MIPCC than MIPWF6, and the imprinting factors of WF on MIPWF6 and MIPCC, respectively, are 2.68 and 5.03 using 20mM sodium phosphate buffer − acetonitrile (30/70, v/v)(final pH 6.1) as the mobile phase. This result indicates that the use of CC as a template molecule instead of WF could be useful for getting a higher imprinting factor for WF and for avoiding the leakage problem in the assay of WF in LC.

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.

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

AbstractSpontaneous 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 bytrans–cisphotoisomerization, which allows a fast and reversible photoinduced switching between chiral and achiral states with non‐polarized light.

Characterization of a Liquid Crystal System for Sustained Release of a Peptide BMS-686117.

Liquid crystal lipid-based formulations are an effective approach to prolong pharmacokinetics and reduce burst release of a drug on subcutaneous delivery. The objective of this paper was to investigate the influence of phase structures of a lipid-based liquid crystal delivery system and its associated mechanical properties on the release profile of a peptide. It was hypothesized that release of drug molecules are closely related to the mechanical properties that are controlled by phase structures. Experimentally, the relationship between phase structures of lipid liquid crystal system-soy phosphatidyl choline (SPC) and glycerol dioleate (GDO) in water were characterized by polarized light microscopy and small angle X-ray diffraction. Their rheological properties were evaluated with a rheometer and the in vitro release of the peptide as a measure drug release from the LC-depot injection. Three phases: disordered phase, lamellar phase, mixtures of cubic, lamellar, and hexagonal phases were detected by varying formulation compositions. A significant difference in rheological behavior was observed. The disordered phase displayed some attributes of typical Newtonian fluid with lowest viscosity while the lamellar phase showed a shear thinning behavior. Regarding the mechanical strength, the lamellar phase presents the highest storage modulus due to its layer structure followed by mixed phases. Comparing release profiles, the lamellar phase produced a fast release followed by the mixture of phases. In conclusion, this study demonstrates the ability to characterize LC phase structures with microscopy, small angle X-ray diffraction, and rheological measurements and their link to modulating a peptide release profile.

Fabrication of Liquid Crystalline Polyurethane Networks with a Pendant Azobenzene Group to Access Thermal/Photoresponsive Shape-Memory Effects.

Herein, we report a novel thermal/photoresponsive shape-memory polyurethane network with a pendant azobenzene group by utilizing its anisotropic-isotropic phase transitions and photoresponsive feature concurrently. To achieve this goal, the side-chain liquid crystalline polyurethane networks based on the pendant azobenzene group [SCLCPU(AZO)-Ns] were developed in a well-defined architecture. The smectic C nature of an LC phase in the polyurethane networks was confirmed by differential scanning calorimetry, polarized optical microscopy, and one-dimensional and two-dimensional wide-angle X-ray diffraction. The well-defined architecture-made SCLCPU(AZO)-N displays two distinct transition temperatures (Ttrans) (Tg and Tcl), with a difference of about 40 °C. Consequently, the excellent triple-shape-memory effect in this network was demonstrated by cyclic thermomechanical analysis. By making full use of the trans-cis photoisomerization of azobenzene, the reversible bending and unbending behaviors were realized under the light irradiation with wavelengths of 450 and 550 nm, respectively.

Rod-Disk互換液晶:エーテル基で結合したアゾベンゼン-トリフェニレン誘導体におけるメチレンスペーサ長の液晶相への影響

Rod-Disk互換液晶:エーテル基で結合したアゾベンゼン-トリフェニレン誘導体におけるメチレンスペーサ長の液晶相への影響

Terahertz artificial birefringence and tunable phase shifter based on dielectric metasurface with compound lattice

A dielectric metasurface with line-square compound lattice structure has been fabricated and demonstrated in the terahertz (THz) regime by the THz time-domain spectroscopy and numerical simulation. A polarization dependent electromagnetically induced transparency (EIT) effect is achieved in this metasurface due to the mode coupling and interference between the resonance modes in line and square subunits of the metasurface. Accompany with the EIT effect, a large artificial birefringence effect between two orthogonal polarization states is also observed in this compound metasurface, of which birefringence is over 0.6. Furthermore, the liquid crystals are filled on the surface of this dielectric metasurface to fabricate an electrically tunable THz LC phase shifter. The experimental results show that its tunable phase shift under the biased electric field reaches 0.33π, 1.8 times higher than the bare silicon, which confirms the enhancement role of THz microstructure on the LC phase shift in the THz regime. The large birefringence phase shift of this compound metasurface and its LC tunable phase shifter will be of great significance for potential applications in THz polarization and phase devices.

Thermotropic and barotropic phase transitions on diacylphosphatidylethanolamine bilayer membranes

The bilayer phase transitions of four diacylphosphatidylethanolamines (PEs) with matched saturated acyl chains (Cn=12, 14, 16 and 18) and two PEs with matched unsaturated acyl chains containing a different kind of double bonds were observed by differential scanning calorimetry under atmospheric pressure and light-transmittance measurements under high pressure. The temperature-pressure phase diagrams for these PE bilayer membranes were constructed from the obtained phase-transition data. The saturated PE bilayer membranes underwent two different phase transitions related to the liquid crystalline (Lα) phase, the transition from the hydrated crystalline (Lc) phase and the chain melting (gel (Lβ) to Lα) transition, depending on the thermal history. Pressure altered the gel-phase stability of the bilayer membranes of PEs with longer chains at a low pressure. Comparing the thermodynamic quantities of the saturated PE bilayer membranes with those of diacylphosphatidylcholine (PC) bilayer membranes, the PE bilayer membranes showed higher phase-transition temperatures and formed more stable Lc phase, which originates from the strong interaction between polar head groups of PE molecules. On the other hand, the unsaturated PE bilayer membranes underwent the transition from the Lα phase to the inverted hexagonal (HII) phase at a high temperature and this transition showed a small transition enthalpy but high pressure-responsivity. It turned out that the kind of double bonds markedly affects both bilayer-bilayer and bilayer-nonbilayer transitions and the Lα/HII transition is a volume driven transition for the reconstruction of molecular packing. Further, the phase-transition behavior was explained by chemical potential curves of bilayer phases.

Tailoring Pore Size and Chemical Interior of near 1 nm Sized Pores in a Nanoporous Polymer Based on a Discotic Liquid Crystal.

A triazine based disc shaped molecule with two hydrolyzable units, imine and ester groups, was polymerized via acyclic diene metathesis in the columnar hexagonal (Colhex) LC phase. Fabrication of a cationic nanoporous polymer (pore diameter ∼1.3 nm) lined with ammonium groups at the pore surface was achieved by hydrolysis of the imine linkage. Size selective aldehyde uptake by the cationic porous polymer was demonstrated. The anilinium groups in the pores were converted to azide as well as phenyl groups by further chemical treatment, leading to porous polymers with neutral functional groups in the pores. The pores were enlarged by further hydrolysis of the ester groups to create ∼2.6 nm pores lined with −COONa surface groups. The same pores could be obtained in a single step without first hydrolyzing the imine linkage. XRD studies demonstrated that the Colhex order of the monomer was preserved after polymerization as well as in both the nanoporous polymers. The porous anionic polymer lined with −COOH groups was further converted to the −COOLi, −COONa, −COOK, −COOCs, and −COONH4 salts. The porous polymer lined with −COONa groups selectively adsorbs a cationic dye, methylene blue, over an anionic dye.

Effect of linking groups on 2, 5-disubstituted thiophene with chalcone as the side arm containing bent-core materials

ABSTRACTNovel bent-core materials containing a central core of 2, 5-disubstituted thiophene with chalcone as the side arm were synthesized and characterized to determine the structure–property relationship. The structural difference between two materials is the linking group in the thiophene and chalcone side arm. Chalcone is linked with thiophene by ester group in material I, while ester group is replaced with imine group in material II. The change in linking group exhibited a drastic difference in their physicochemical and intramolecular behaviors. Material I exhibits a hexagonal columnar mesophase at below room temperature, whereas material II exhibits a crystalline phase. Both liquid crystalline and crystalline properties were examined from polarized optical microscopy (POM), differential scanning calorimetry (DSC), and powder X-ray diffraction (PXRD) analyses. The highlight of this work is material I revealed a hexagonal columnar phase in the temperature ranges 22–38°C and undergoes photocrosslinking in UV light; contrarily, material II exhibits neither LC phase nor photocrosslinking property.

Secondary Interactions of Graphene Oxide on Liquid Crystal Formation and Stability

Graphene oxide liquid crystals (GO LC) prove their potential usefulness in a new design of carbon scaffold composites with ordered structures from nano to macroscale. This paper highlights the degree of GO functionalization as a notable influencing factor on GO LC formation. The large amount of oxygen functional groups, which cause secondary interactions between GOs, decrease the critical concentration for the phase transitions from isotropic to biphasic to nematic phases. In the biphasic state where isotropic and anisotropic phases coexist, highly oxidized GO sheets spontaneously develop LC phases among themselves. Furthermore, the strong hydrogen bonding networks between GO sheets govern the stabilization of the GO aqueous dispersion for a long period. This unique behavior can be used to design GO‐based architecture with controllable density and ordering.

Thermal and phase transformation behavior of epoxy‐functional graphene oxide/liquid crystalline epoxy composite

In this study, epoxy‐functional graphene oxide/liquid crystalline epoxy (efGO/LCE) composite was obtained by mixed LCE with efGO, which was obtained by modifying graphene oxide (GO) with LCE in alkaline condition. The influence of efGO content on glass transition temperature (Tg), thermal stability, and phase transformation behaviors of the composite were characterized by thermogravimetric analysis, differential scanning calorimetry, and polarized optical microscopy. The results reveal that the right amount of efGO can keep the LC property of LCE while GO inhibits the formation of LC phase of LCE. POM photographs of efGO/LCE composites show clear bright specks under polarized light, suggesting heterogeneous nucleation effects is in favor of formation of LC phase. Moreover, the initial decomposition temperature of efGO/LCE composite is increased to 380°C from that of pure LCE at 350°C when efGO content is 1 wt%. It suggests that efGO is effective to increase thermal decomposition temperature and glass transition temperature (Tg) due to cross‐linking between efGO and LCE. POLYM. COMPOS., 39:E1391–E1397, 2018. © 2017 Society of Plastics Engineers

Characterization and stability study of cranberry flavonoids in lipid liquid crystalline systems

The main objective of the present study was to investigate mixtures of soy phosphatidylcholine (SPC) and glycerol dioleate (GDO) as encapsulation matrices for cranberry flavonoids. The effects of flavonoids loading into non‐aqueous formulations, non‐lamellar liquid crystalline phases, and their colloidal dispersions were studied by using synchrotron small angle X‐ray diffraction, dynamic light scattering. Flavonoids incorporation is discussed with respect to the lipid aggregation behavior, self‐assembled nanostructure, and chemical stability by using antioxidant activity assay. The obtained results show that SPC/GDO‐based formulations can incorporate relatively high amounts of flavonoids and serve as liquid crystalline delivery vehicles in the form of bulk phases or colloidal dispersions.Practical applications: Our results show that SPC/GDO‐based formulations can incorporate relatively high amounts of cranberry flavonoids. The effect flavonoid extracts on the nanostructure of bulk SPC/GDO LC phases are lipid weight ratio‐dependent. Flavonoids loaded into SPC/GDO‐based formulations and LC phases retain their antioxidant properties. The self‐assembled lipid liquid crystalline systems protect bioactive compounds from degradation. These facts are important for the community working in the field of self‐assembly of lipid structures, food chemistry, and delivery vehicles of nutraceuticals.Soy phosphatidylcholine lipids (SPC) and glycerol dioleate (GDO) formed lipid‐based liquid crystal systems can be successfully applied for entrapment of natural cranberries flavonoids. After full hydration LC formulations can easily create self‐assembled non‐lamellar LC systems with different nanostructures. The stability studies have shown that the flavonoids loaded in SPC/GDO‐based systems retain their antioxidant properties at least up to 30 days.

Lyotropic liquid crystal based on zinc oxide nanoparticles obtained by microwave solvothermal synthesis

The ZnO nanoparticles, obtained by microwave solvothermal synthesis, were used for the liquid crystal phase preparation. The structure of the material was investigated by X-ray diffraction (XRD), helium pycnometry, specific surface area (SSA), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM). The stability of aqueous suspensions was monitored by Multiple Light Scattering (MLS) technique and the average agglomerate size in suspensions was obtained by dynamic light scattering (DLS) technique. The lyotropic columnar hexagonal phase was formed by doping ZnO nanoparticles into the cetylpiridinium chloride/water/hexanol system. The structure of this phase was confirmed by x-ray diffraction. The luminescent properties of the LC phase were compared with properties of ZnO nanoparticles isolated in solution and analogues lyotropic system without nanoparticles.

A Novel Coarse-Grained Model to Study Liquid-Liquid Phase Separation of Disordered Proteins

Recent studies have led to the discovery of droplets composed of disordered protein chains in a separate liquid-like phase. Such assemblies have been found to be relevant to physiological function as membraneless compartments in living cells including the nucleolus and ribonucleoprotein (RNP) granules as well as many organelles in prokaryotic cells (1). The thermodynamic driving force for this phase separation, however, is still not well characterized. Fused in Sarcoma (FUS) is an RNA binding protein that naturally forms these droplets as RNP granules which aid with DNA repair. The low complexity domain, FUS LC is a fully disordered domain and has been observed to form these droplets on its own in vitro (2). Mutations of FUS can result in transformation of these assemblies into poorly soluble aggregates involved in the pathogenesis of Amyotrophic Lateral Sclerosis and Frontotemporal Dementia (3). As the spatiotemporal scales involved in the phase separation of proteins cannot be resolved using fully detailed all-atom models, we develop a simple Cα;-based coarse-grained model that treats each amino acid in the chain as a single interaction site. The model is parameterized to treat each of the twenty naturally occurring amino acids differently in order to capture sequence-specific effects. Development of the proposed model involves top-down comparisons with experimental data available from the recent literature as well as comparisons with atomistic simulations of a single chain. We then use this model to characterize the droplet formation for FUS LC including the proposed transition from liquid-like to solid-like aggregates. We are also able to capture known trends in FUS LC phase separation as a function of salt concentration and disease-related mutations. This model should aid in the molecular understanding of phase behavior of disordered proteins thus aiding in development of therapeutic strategies.1.Brangwynne, C. P.; Eckmann, C. R.; Courson, D. S.; Rybarska, A.; Hoege, C.; Gharakhani, J.; Julicher, F.; Hyman, A. A. Science 2009, 324, 1729-17322.Burke, K. A.; Janke, A. M.; Rhine, C. L.; Fawzi, N. L. Molecular Cell 2015, 60, 231-2413.Patel, A.; Lee H. O.; Jawerth, L.; Dechsel, D.; Hyman, A. A.; Alberti, S. and othersCell 2015, 162, 1066-1077

Synthesis, characterization, and mesomorphic investigation of vinyl ester-substituted chalcones and effect of lateral ‒NO2 and ‒OCH3 group

ABSTRACTA novel homologous series of α-4-(4′-n-alkoxy cinnamoyloxy) phenyl β-2″-nitro, 3″–4″ di methoxy benzoyl ethylenes, H2n+1CnO‒C6H4‒CH˭CH‒COO‒C6H4‒CO‒CH˭CH‒C6H2(NO2) (OCH3)2 (n = 1–8, 10, 12, 14, 16, 18) has been synthesized. All these compounds have been characterized by suitable spectroscopic techniques. C1 homologue is nonmesogenic, while C2 homologue shows enantiotropic nematogenic property and the rest of the homologous (C3‒C18) displayed enantiotropically smectogenic plus nematogenic phase. Phase transition temperatures and textures of the LC phase were determined by an optical polarizing microscopy (POM) equipped with a heating stage. The mesomorphic properties of these compounds were confirmed by differential scanning calorimetry (DSC) analysis.

Large negative magneto-LC effects induced by racemic dimerization of liquid crystalline nitroxide radicals with a terminal cyano group

Large negative magneto-LC effects occur in the LC phase of a racemate of a chiral nitroxide radical with a terminal cyano group.

Synthesis and self-assembly of photoresponsive and luminescent polycatenar liquid crystals incorporating an azobenzene unit interconnecting two 1,3,4-thiadiazoles

Target compounds can self-assemble into a thermotropic LC phase sequence of SmC–Colhex–CubI and have binding selectivity to Cu2+.

Polyphilic hydrogen bonded block molecules involving semiperfluorinated and silylated molecular fragments.

2,4-Diamino-6-phenyl-1,3,5-triazines grafted with one or two semiperfluorinated chains at the phenyl substituent have been investigated in binary mixtures with one-chain and two-chain oligo(dimethylsiloxy) terminated 4-alkoxy- and 3,4-dialkoxybenzoic acids. Equimolar mixtures of the triazines with the complementary acids form discrete double hydrogen-bonded heterodimers with an elongated central core. Mesomorphic properties are observed only if at least two terminal fluoroalkyl chains are attached to the triazine entity. Three to four heterodimers generate aggregates with preferably parallel adjusted rod-like H-bonded cores. The space requirement of the segregated peripheral fluoroalkyl and oligosiloxane segments considerably exceeds that of the central core region, leading to an overall circular geometry of the associates which organize in columnar LC phases. The chains initiate a local segregation which is however not long range and retains a time and space averaged two-dimensional hexagonal lattice.

Influence of main chain on the phase behaviors of side‐chain liquid‐crystalline polymers with triphenylene mesogens of long alkyl tail substituents

ABSTRACTA series of side‐chain liquid‐crystalline polymers (SCLCPs) containing triphenylene mesogen, in which the long alkyl tail Tp connected directly with main chain, were synthesized successfully. The chemical structures of the monomers were confirmed by 1H NMR and mass spectrometry. The phase behaviors of polymers were investigated by a combination of techniques, including DSC, POM, 1D/2D WAXD, and SAXS. The experimental results suggested that the type of main chain played an important role in the LC phase structures of these polymers. Because of the steric effects of side chains and the coupling effects between the Tp moieties and the main chains, all the polymers exhibited columnar phase. However, the SCLCPs with poly(vinyl benzene methyl ether) or polynorbornene backbone displayed hexagonal columnar phase, while those with polyacrylate or polymethacrylate backbone presented columnar nematic phase, and the one with poly(vinyl benzoate) main chain showed rectangular columnar phase. Moreover, the clearing temperatures (Ti) changed with change in main chain. Especially, the Ti of the SCLCP with polymethacrylate backbone was above 300 °C. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017, 55, 754–766