Search

Encapsulation of highly emissive alkynylpyrenes with permethylated α-cyclodextrin (PM-α-CD) followed by capping reaction yielded alkynylpyrene-based [3]rotaxanes. The [3]rotaxane emitted only blue light of monomeric pyrene under various circumstances such as lipophilic, hydrophilic, and even condensed states and exhibited extremely high stability for UV irradiation. These properties would result because PM-α-CD, like bulletproof glass, protected the alkynylpyrene core from the attack of another excited alkynylpyrene and singlet oxygen generated by the energy transfer from the excited alkynylpyrene. [ABSTRACT FROM AUTHOR]

We prepared a rod-like molecule, 4-[4-(7-hydroxyheptyloxy)phenyl]-1-(4-hexylphenyl)-2,3-difluorobenzene, and investigated its physical properties using polarized optical microscopy (POM), differential scanning calorimetry (DSC), and X-ray diffraction (XRD). The compound was found to exhibit nematic, smectic A, and smectic C phases. A smectic-like layer ordering was detected using XRD at low temperatures of the nematic phase. The nematic phase changed to a smectic A phase when cooled, with no accompanying enthalpy change. Analyses using XRD and POM revealed that the smectic C phase consists of three states: conventional SmC with a monolayered structure, monolayered SmC′ possessing an additional weak bilayered character, and SmC′′ possessing both monolayered and bilayered structures. Furthermore, a discontinuous increase in birefringence of a homeotropically aligned sample of the compound was observed in the SmC′′ phase. Interlayer interactions organized by hydrophobic−hydrophilic amphiphilicity and orthogonal−tilt amphiphilicity are discussed to explain the appearance of the unusual liquid-crystalline phases with a hierarchical structure. [ABSTRACT FROM AUTHOR]

A novel dichiral compound possessing both an asymmetric axis and a chiral centre induces opposite twist senses and distinct helical pitches in different host nematic liquid crystals; the host–guest effect on chirality transfer is discussed in terms of molecular recognition. [ABSTRACT FROM AUTHOR]

Background: We recently demonstrated the cytotoxicity of liquid crystal precursors (hereafter referred to as "mesogenic compounds") in the human non-small cell lung cancer (NSCLC) cell line A549 which carry wild-type p53. p53 mutations are observed in 50 % of NSCLC and contribute to their resistance to chemotherapy. To develop more effective and cancer-specific agents, in this study, we investigated the structure-activity relationships of mesogenic compounds with cytotoxic effects against multiple NSCLC cells.Methods: The pharmacological effects of mesogenic compounds were examined in human NSCLC cells (A549, LU99, EBC-1, and H1299) and normal WI-38 human fibroblast. Analyses of the cell cycle, cell-death induction, and capsases expression were performed.Results: The 3-ring compounds possessing terminal alkyl and hydroxyl groups (compounds C1-C5) showed cytotoxicity in NSCLC cells regardless of the p53 status. The compounds C1 and C3, which possess a pyrimidine at the center of the core, induced G2/M arrest, while the compounds without a pyrimidine (C2, C4, and C5) caused G1 arrest; all compounds produced caspase-mediated cell death. These events occurred in a p53-independent manner. Furthermore, it was suggested that compounds induced cell death through p53-independent DNA damage-signaling pathway. Compounds C2, C4, and C5 did not show strong cytotoxicity in WI-38 cells, whereas C1 and C3 did. However, the cytotoxicity of compound C1 against WI-38 cells was improved by modulating the terminal alkyl chain lengths of the compound.Conclusions: We showed the p53-indepdent structure-activity relationships of mesogenic compounds related to the cytotoxic effects. These structure-activity relationships will be helpful in the development of more effective and cancer-specific agents. [ABSTRACT FROM AUTHOR]

Water-in-supercritical CO2 microemulsions formed using the hybrid F-H surfactant sodium 1-oxo-1-[4-(perfluorohexyl)phenyl]hexane-2-sulfonate, FC6-HC4, have recently been shown to have the highest water-solubilizing power ever reported. FC6-HC4 demonstrated the ability to outperform not only other surfactants but also other FCm-HCn analogues containing different fluorocarbon and hydrocarbon chain lengths (Sagisaka, M. et al. Langmuir 2015, 31, 7479-7487). With the aim of clarifying the key structural features of this surfactant, this study examined the phase behavior and water/supercritical CO2 aggregate formation of 1-oxo-1-[4-(perfluorohexyl)phenyl]hexane (Nohead FC6-HC4), which is an FC6-HC4 analogue but now, interestingly, without the sulfonate headgroup. Surprisingly, Nohead FC6-HC4, which would not normally be identified as a classic surfactant, yielded transparent single-phase W/CO2 microemulsions with polar cores able to solubilize a water-soluble dye, even at pressures and temperatures so low as to approach the critical point of CO2 (e.g., ∼100 bar at 35 °C). High-pressure small-angle scattering (SANS) measurements revealed the transparent phases to consist of ellipsoidal nanodroplets of water. The morphology of these droplets was shown to be dependent on the pressure, Nohead FC6-HC4 concentration, and water-to-surfactant molar ratio. Despite having almost the same structure as Nohead FC6-HC4, analogues containing both shorter and longer hydrocarbons were unable to form W/CO2 microemulsion droplets. This shows the importance of the role of the hydrocarbon chain in the stabilization of W/CO2 microemulsions. A detailed examination of the mechanism of Nohead FC6-HC4 adsorption onto the water surface suggests that the hexanoyl group protrudes into the aqueous core, allowing for association between the carbonyl group and water. [ABSTRACT FROM AUTHOR]

This study reports unusual behaviorof aqueous-phase lamellar aggregateswith a new class of hybrid surfactant, CB-B2ES, having mesogenic units{6-[4-(4-cyanophenyl)phenyloxy]hexyl} and temperature-sensitive oxyethylated(butoxyethoxyethyl) tails. These tails are poorly miscible and likelyto microsegregate if the surfactant molecules assemble. Lamellar aggregatesappear at CB-B2ES concentrations higher than 5 wt % and were foundto undergo repeat formation/breakdown periodically at 30 °C,with an average domain lifetime of ∼10 s. To investigate effectsof the temperature-sensitive oxyethylene units on the hydrophilic/lipophilicbalance (HLB) of the CB-B2ES bilayers, a fluorescence probe 1-pyrene-carboxaldehidewas solubilized in the mixtures to sense the micro-environmental polarities.Fluorimetric measurements suggested that the polarity of CB-B2ES bilayersis very similar to that of the non-ethoxylated CB-B2ES analogue athigh temperatures (≥65 °C). However, for CB-B2ES, polarityincreased with a decreasing temperature, in contrast with the smalldecrease in polarity observed for analogous non-ethoxylated bilayers.This is consistent with increased hydration of the oxyethylene unitsin CB-B2ES bilayers at low temperatures. The periodic formation/breakdownand cooling-induced hydrophilicity of the CB-B2ES lamellar aggregatesdid not appear in the non-hybrid and/or non-ethoxylated surfactantsystems. Therefore, the combination of two unsymmetrical tails, onecontaining oxyethylene units and the other containing cyanobiphenylterminal tips, must play an important role promoting this unusualbehavior. [ABSTRACT FROM AUTHOR]

Hybrid surfactants containing bothfluorocarbon (FC) and hydrocarbon(HC) chains have recently been shown to solubilize water and formelongated reversed micelles in supercritical CO2. To clarifythe most effective FC and HC chain lengths, the aggregation behaviorand interfacial properties of hybrid surfactants FCm-HCn(FC length m/HC length n= 4/2, 4/4, 6/2, 6/4, 6/5, 6/6, and 6/8) were examinedin W/CO2mixtures as functions of pressure, temperature,and water-to-surfactant molar ratio (W0). The solubilizing power of hybrid surfactants for W/CO2microemulsions was strongly affected by not only the FC length butalso by that of the HC. Although the surfactants having short FC and/orHC tails (namely, m/n= 4/2, 4/4,and 6/2) did not dissolve in supercritical CO2(even at∼17 mM, ≤400 bar, temperature ≤ 75 °C, and W0= 0–40), the other hybrid surfactantswere able to yield transparent single-phase W/CO2mixturesidentified as microemulsions. The solubilizing power of FC6-HCmsurfactants reached a maximum (W0∼ 80 at 45 °C and 350 bar) with a hydrocarbonlength, m, of 4. The W0value of 80 is the highest for a HC-FC hybrid surfactant, matchingthe highest value reported for a FC surfactant which contained moreFC groups. High-pressure small-angle neutron scattering measurementsfrom FCm-HCn/D2O/CO2microemulsions were consistent with growth of the microemulsiondroplets with increasing W0. In addition,not only spherical reversed micelles but also nonspherical assemblies(rodlike or ellipsoidal) were found for the systems with FC6-HCn(n= 4–6). At fixed surfactantconcentration and W0(17 mM and W0= 20), the longest reversed micelles wereobtained for FC6-HC6 where a mean aspect ratio of 6.3 was calculatedfor the aqueous cores. [ABSTRACT FROM AUTHOR]

Chirality's effects on physical properties of materials and how chirality arises have persisted as attractive issues in chemistry. We prepared a homologous series of achiral liquid crystal trimers in which three phenylpyrimidine units are connected via flexible heptamethylene spacers. An equimolecular mixture of a trimer with a nematic (N) phase and that with smectic A (SmA), smectic C (SmC), and smectic B phases was found to exhibit an N phase, a SmC phase, and a B4 phase composed of chiral domains with opposite handedness. The chiral characteristics of the B4 phase were confirmed by uncrossing the polarizers in opposite directions. XRD measurements reveal that both SmC and B4 phases have an interdigitated layer structure. That molecular interdigitation might form a supermolecular bent configuration that can produce saddle splay curvature to drive the B4 phase. [ABSTRACT FROM AUTHOR]

The fluorinated double-tailed glutarate anionic surfactant, sodium 1,5-bis[(1H,1H,2H,2H-perfluorodecyl)oxy]-1,5-dioxopentane-2-sulfonate (8FG(EO)2), was found to stabilize water-in-supercritical CO2microemulsions with high water-to-surfactant molar ratios (W0). Studies were carried out here to obtain detailed information on the phase stability and nanostructure of the microemulsions by using a high-pressure UV−vis dye probe and small-angle neutron scattering (SANS) measurements. The UV−vis spectra, with methyl orange as a reporter dye, indicated a maximum attainable W0of 60 at 45 and 75 °C, and SANS profiles indicated regular droplet swelling with a linear relationship between the water core nanodroplet radius and W0. This represents the highest water solubilization reported to date for any water-in-CO2microemulsion. Further analysis of the SANS data indicated critical packing parameters for 8FG(EO)2at the microemulsion interface >1.34, representing approximately 1.1 times the value for common aerosol-OT in water-in-heptane microemulsions under equivalent conditions. [ABSTRACT FROM AUTHOR]

A chiral liquid crystal oligomer, (R)-1-methylheptyl 4′-{8-[4-(5-octylpyrimidin-2-yl)phenyloxy]octanoyloxy}biphenyl-4-carboxylate, was prepared. Its physical properties were investigated using optical microscopy, differential scanning calorimetry, and X-ray diffraction. The oligomer was found to exhibit two ferrielectric smectic C phases with a wide temperature range between ferroelectric and antiferroelectric smectic C phases. Furthermore, ferrielectric-like ordering was observed in a racemic mixture of the enantiomers. The oligomeric effect can produce highly chirality-dependent ordering in the racemic system. [ABSTRACT FROM AUTHOR]

Phase behavior was investigated for water/supercritical CO 2(W/scCO 2) microemulsions stabilized with sodium bis(1 H,1 H,2 H,2 H-heptadecafluorodecyl)-2-sulfosuccinate (8FS(EO) 2) mixed with various guest surfactants. Only for the mixtures with fluorocarbon−hydrocarbon hybrid anionic surfactants (FC6-HC n), the maximum water-to-surfactant molar ratio ( W0c) was larger than that estimated from linear interpolation of the W0cvalues for pure 8FS(EO) 2and pure guest surfactant. Fourier transform infrared (FT-IR) measurement for the microemulsion revealed that the mixing of 8FS(EO) 2with FC6-HC ncan prevent a phase transition from the microemulsion to the liquid crystal even in the presence of excess water. It was also found from the measurement of water/scCO 2interfacial tension that the area occupied per surfactant molecule was markedly increased by the mixing with FC6-HC n. The loose molecular packing, probably due to a microsegregation of 8FS(EO) 2and FC6-HC n, is consistent with the enhanced stability of the microemulsion upon surfactant mixing. [ABSTRACT FROM AUTHOR]

After preparing a novel amphiphilic liquid crystal hexamer possessing six cyanobiphenyl moieties and a semiperfluorinated alkyl chain, we used optical microscopy, differential scanning calorimetry, and X-ray diffraction to investigate its physical properties. The liquid crystal oligomer, 1, 10-bis{3, 4, 5-tris[6-(4′-cyanobiphenyl-4-yloxy)hexyloxy]benzoyloxy}-1H,1H,10H,10H-heptadecafluorodecane, was found to exhibit a bilayer smectic A to intercalated smectic A transition accompanying a discontinuous decrease in layer spacings. The transition is attributable to a change in its molecular conformation from a folded (or bent) to a linear structure. [ABSTRACT FROM AUTHOR]

The effect of surfactant tail structure on the stability of a water/supercritical CO2microemulsion (W/scCO2E) was examined for various fluorinated double-tail anionic surfactants of different fluorocarbon chain lengths, F(CF2)n(n4, 6, 8, and 10), and oxyethylene spacer lengths, (CH2CH2O)m2(m2 and 4). The phase behavior of the water/surfactant/CO2systems was studied over a wide range of CO2densities from 0.70 to 0.85 g/cm3(temperatures from 35 to 75 °C and pressures up to 500 bar) and corrected water-to-surfactant molar ratios (W0c). All of the surfactants yielded a W/scCO2E phase, that is, a transparent homogeneous phase with a water content larger than that permitted by the solubility of water in pure CO2. With increasing W0c, a phase transition occurred from the E phase to a macroemulsion or a lamella-like liquid crystal phase. The maximum W0cvalue was obtained at a tail length of 12−14 Å, indicating the presence of an optimum surfactant tail length for W/scCO2E formation. [ABSTRACT FROM AUTHOR]

The effects of surfactant mixing on interfacial tension and on microemulsion formation were examined for systems of air/water and water/supercritical CO2(scCO2) interfaces and for water/scCO2microemulsions. A fluorinated surfactant, sodium bis(1H,1H,2H,2H-heptadecafluorodecyl)-2-sulfosuccinate (8FS(EO)2), was mixed with the three hydrocarbon surfactants, Pluronic L31, Tergitol TMN-6, and decyltrimethylammonium chloride (DeTAC), at equimolar ratio. For all the cases, the interfacial tension was significantly lowered by the mixing. The positive synergistic effect suggests that the mixed surfactants tend to pack more closely on the interface than the pure constituents. It was found, however, that the microemulsion formation in scCO2was never facilitated by the mixing, except for the case of TMN-6. This is probably due to the segregation of the surfactants into hydrocarbon-rich and fluorocarbon-rich phases on the microemulsion surface. [ABSTRACT FROM AUTHOR]