- A Highly Ordered Quantum Dot Supramolecular Assembly Exhibiting Photoinduced Emission Enhancement
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Multicomponent supramolecular assembly systems enable the generation of materials with outstanding properties, not obtained from single-component systems, via a synergetic effect. Herein, we demonstrate a novel supramolecular coassembly system rendering highly ordered quantum dot (QD) arrangement structures formed via the self-assembly of azobenzene derivatives, where the photocontrollable photoluminescence (PL) properties of the QDs are realized based on photoisomerization. Upon mixing the assembled azobenzene derivatives and QDs in apolar media, a time-evolution coaggregation into hierarchical nanosheets with a highly ordered QD arrangement structure occurs. Upon photoirradiation, the nanosheets transform into ill-defined aggregates without arranged QDs together with enhancing the PL intensity. In days, the photoirradiated coaggregates undergo recovery of the PL properties corresponding to the arranged QDs through thermal isomerization.
- Yamauchi, Mitsuaki,Yamamoto, Seiya,Masuo, Sadahiro
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- Vinyl-terminated liquid-crystalline dendrimers based on dendritic polyols and their siloxane-based elastomers
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A new series of side-chain liquid-crystalline dendrimers (LCDs) by grafting vinyl-terminated phenyl benzoate-based promesogens to a novel polypropyleneimine-derived dendritic polyols are reported. Polarized optical microscopy and X-ray diffraction studies
- Lin, Yuteng,Sun, Jianzhong
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- Structure-properties relationships in liquid crystal thiols
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Two new series of thiols were studied in order to establish the structure-properties relationships. First series consists of compounds with three or four aromatic rings as rigid part of mesogen and the second contains thiols with a flexible chain attached
- Cseh, Liliana,Mehl, Georg
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p. 879 - 885
(2014/08/18)
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- Bent-core systems based on [1,3,4]oxadiazole core with shape biaxiality
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The present paper is presenting the Synthesis and characterization of new [1,3,4]oxadiazole derivatives obtained by attaching different mesogenic units to the central core. Liquid crystals properties analysis by POM and DSC techniques is presented and structure-properties correlations are discussed.
- Apreutesei, Daniela,Mehl, Georg H.
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scheme or table
p. 527 - 533
(2009/12/24)
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- Bent-core liquid crystal (LC) decorated gold nanoclusters: Synthesis, self-assembly, and effects in mixtures with bent-core LC hosts
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We present the first synthesis of a series of thiol-, thioacetate-, and xanthate-terminated bent-core derivatives, as well as the preparation of gold nanoclusters using the thiol-terminated bent-core compounds. The mesomorphic properties of the bent-core compounds have been investigated by polarizing optical microscopy (POM), differential scanning calorimetry (DSC), small angle X-ray scattering (SAXS), and electro-optic tests. From this series, the mono-xanthate derivatives form rectangular or hexagonal columnar phases, and the mono-thiol derivative with shorter alkyl chains forms a metastable, likely smectic, phase. All other bent-core compounds and intermediates exclusively form disordered or multi-layer lamellar crystalline solid modifications. High-resolution transmission electron microscopy (HR-TEM) images of the bent-core functionalized gold nanoclusters prepared from the thiol-terminated derivatives, taken after slow evaporation of the solvent, provide evidence for the formation of self-assembled nanocluster arrays. Upon dispersion of these gold nanoclusters in two structurally related bent-core LC hosts (one forming a SmCPA, and the second with a terminal double bond displaying a Colr phase), a shift in the surface plasmon resonance was observed indicating a LC host-dependent aggregation of the nanoparticles. Finally, we report initial results on the effects of different concentrations of these nanoclusters on the thermal properties as well as the applied voltage/current response of the parent SmCPA host.
- Marx, Vanessa M.,Girgis, Hidy,Heiney, Paul A.,Hegmann, Torsten
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supporting information; experimental part
p. 2983 - 2994
(2010/02/27)
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- Cholesteric silatranes
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Most liquid crystals with a C3 symmetry have so far been discotic systems, e.g., triphenylenes. In the context of calamitic systems research has concentrated on triptycenes and to a lesser extend on silatranes. In this contribution we report our investigations of cholesteric silatrane systems, which have been obtained by connecting a tribenzylsilatrane core to cholesteric groups via alkyl and siloxane spacer groups.
- Alvarez,Mehl
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p. 259/2125-267/2133/
(2007/10/03)
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- Thermal behaviour and mesophase structure of cyclic oligosiloxanes with chiral mesogenic groups
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Chiral, smectogenic pendant groups have been covalently attached to cyclic oligosiloxanes by hydrosilylation. Differential scanning calorimetry, optical polarising microscopy, and X-ray diffraction measurements reveal liquid crystalline properties for all
- Soltysiak, Joanna T.,Bialecka-Florjanczyk, Ewa,Kowalczyk, Ewa,Przedmojski, Jan
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p. 217/[1259]-230/[1272]
(2007/10/03)
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- Mixed cellulose-derived benzoates bonded on allylsilica gel as HPLC chiral stationary phases: Influence of the introduction of an aromatic moiety in the fixation substituent
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Several mixed alkenoxybenzoyl/benzoates and 10-undecenoyl/benzoates of cellulose were fixed onto allylsilica gel by the radical coupling of double bonds. The introduction of an aromatic group in the fixation substituent modifies the chiral recognition abi
- Garces, Jordi,Franco, Pilar,Oliveros, Laureano,Minguillon, Cristina
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p. 1179 - 1185
(2007/10/03)
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- Study of the ferroelectric liquid crystal 11EB1M7 by means of 2NMR
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In this work, a new procedure for the synthesis of the selectivity deuterium-labeled chiral liquid crystal (+)-(S)-4-[4′-(1-methylheptyloxy)] biphenyl 4(10-undecenylox)benzoate (11EB1M7) has been developed, aimed to the study of its structure, orientational ordering, and dynamic behavior by means of 2H NMR. 11EB1M7 was investigated throughout its mesophasic range, formed by a very rich variety of chiral liquid crystalline phases including blue, cholesteric, TGBA*, and smectic C*. Two isotopomers were synthesized by labeling 11EB1M7 on either the phenyl or the biphenyl moiety of the mesogenic core. This allowed structural information (such as the tilt angle of the rigid fragments of the molecule and the angle between their para axes), orientational order parameters, and individual diffusional coefficients for the various overall and internal motions to be obtained from 2H NMR spectra and relaxation measurements by applying suitable data analyses based on several theoretical models.
- Catalano, Donata,Chiezzi, Leonardo,Domenici, Valentina,Geppi, Marco,Veracini, Carlo Alberto
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p. 10104 - 10113
(2007/10/03)
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- New carbosilane ferroelectric liquid crystalline dendrimers
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For the first time a series of carbosilane ferroelectric liquid crystalline dendrimers of generations 1 - 3 with 8, 16 and 32 terminal ethyl-L-lactate-containing mesogenic groups, respectively, has been synthesised. Structures and purity of all new compounds were confirmed by 1H NMR spectroscopy and GPC analysis. All LC dendrimers synthesised exhibit only a chiral smectic C mesophase in a broad temperature range. The highest spontaneous polarization is about 140 nC/cm2 for the LC dendrimer of the first generation and is reduced with increase of generation number.
- Boiko,Zhu,Vinokur,Rebrov,Muzafarov,Shibaev
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p. 777/343-784/350
(2007/10/03)
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- Self-assembly of β-glucosidase and D-glucose-tethering zeolite crystals into fibrous aggregates
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β-Glucosidase and D-glucose-tethering micrometer-sized zeolite crystals self-assemble into thin (2-20 μm) and very long (>1 cm) fibrous aggregates in water. The process proceeds at a faster rate in a buffer solution of pH 4.8 at which the enzymatic activity is highest. The zeolite and enzyme remain intact within the fibrous material. Furthermore, the enzymatic activity of β-glucosidase is preserved even after they are kept in water for more than 6 months at room temperature. With the zeolite to enzyme weight ratio of 5, all the zeolite crystals are buried within the round fibrils which consist of either a single strand or helical double strands. Upon increasing the ratio to 10, clusters of unburied zeolite crystals appear on the exterior of the fibrils, while narrow flat fibers with smooth surfaces are formed upon decreasing the ratio to 2.5. The process is proposed to initiate by the tight binding between the zeolite-bound D-glucose moieties and β-glucosidase followed by crystallization of the enzyme over the zeolite-bound enzyme monolayer. This report thus reveals a novel behavior of β-glucosidase and demonstrates an unprecedented phenomenon that an enzyme and its substrate-tethering inorganic crystals self-assemble into structured aggregates.
- Lee,Lee,Choi,Park,Yoon
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p. 12151 - 12157
(2007/10/03)
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- Liquid crystalline polymer having a polysiloxane backbone
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A side-chain liquid crystalline polysiloxane having the following formula is disclosed: STR1 wherein Me is methyl; m is an integer of 40 to 80; n is an integer of 1 to 12; Ar is phenylene, biphenylene or naphthalene; Ar' is phenylene or naphthalene; X is halogen or methyl; and R is C1 -C4 alkyl.
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- Ferroelectric Liquid Crystals. Part 3. Achiral Phenyl Benzoates Incorporating a trans-4-Pentylcyclohexyl Moiety
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About twenty substituted phenyl benzoates incorporating a trans-4- pentylcyclohexyl moiety have been synthesised.The synthesis, liquid-crystal transition temperatures, and enthalpies of fusion are reported.The effect of variations chainlength and central
- Kelly, Stephen M.,Buchecker, Richard
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p. 461 - 466
(2007/10/02)
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- Synthesis and chomatographic properties of liquid crystalline polysiloxanes containing steroid substituents
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A series of alkenyl-substituted cholesterol and related steroids have been prepared.These liquid-crystalline compounds were hydrosilylated onto polyhydromethylsiloxane.The polymers have a broad range of liquid crystallinity even if the starting alkenes ha
- Adams, Nathan W.,Bradshaw, Jerald S.,Bayona, Jose-Maria,Markides, Karin E.,Lee, Milton L.
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