- Photoconductive bent-core liquid crystalline radicals with a paramagnetic polar switchable phase
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A series of self-organizing bent-core derivatives 1[12,n], containing a highly π-delocalized stable radical as the central angular structural element, is described. The planarity of the open-shell core permits efficient π-π stacking, which results in the formation of B2 and soft crystalline phases above 100 °C. Optical, XRD and dielectric analyses of 1[12,12] indicate that the ground state of the observed B2 phase is polar antiferroelectric of type SmCAPA exhibiting tristable electro-optical switching. SQUID and EPR measurements revealed strong antiferromagnetic spin-spin exchange interactions below the isotropic phase, which have been estimated at θ = -46 cm-1 with the Curie-Weiss law. Transient photoconductivity was observed in the B2 phase with a hole carrier mobility μh of 1.4 × 10-4 cm2 V-1 s-1
- Shivakumar, Kilingaru I.,Pociecha, Damian,Szczytko, Jacek,Kapu?ciński, Szymon,Monobe, Hirosato,Kaszyński, Piotr
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p. 1083 - 1088
(2020/02/05)
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- Synthesis and characterization of two phenyl ring core-based thiophene mesogens
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Novel thiophene mesogens built with two phenyl ring core and alkoxy terminal chains are synthesized by multistep route. The phenyl ring core is connected to thiophene by ester unit at (a) 2-position and (b) 3-position to yield 2-series of mesogens. The structural characterization of them is accomplished by using spectroscopy tools and the mesophase characteristics are evaluated by HOPM and DSC. The 13C chemical shifts of representative mesogens calculated from DFT by quantum chemical calculations are compared with experimental 13C chemical shifts and further utilized for structural assignment of core unit carbons. A good agreement between calculated and experimental values is noticed. An enantiotropic nematic phase is confirmed for all the mesogens and accordingly threaded nematic texture in HOPM is observed and is supported by DSC transition enthalpy values. The mesophase as well as thermal stabilities of the mesogens are discussed with reference to terminal chain length and position of the linking unit on thiophene.
- Reddy, M. Kesava,Reddy, K. Subramanyam,Prakash,Narasimhaswamy
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- Symmetrical dimer liquid crystals with tilted smectic phases
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Three, series of symmetrical dimer liquid crystals, i.e. bis(dodecyloxybenzoyloxybenzoyloxy)alkanes (BC12) and bis(dodecyloxy- and hexadecyloxybenzoyloxyphenyl) alkanedicarboxylates (QC12 and QC16) with a spacer ranging from two to eight methylene units,
- Achten, Remko,Marcelis, Antonius T.M.,Koudijs, Arie,Sudhoelter, Ernst J.R.
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p. 177/[1219]-184/[1226]
(2007/10/03)
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- Synthesis and liquid crystalline properties of (S)-[4-n-alkyloxy-benzoyloxyphenyl]-4′-[(2-n-alkyloxy)propionyloxy] benzoate
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New series of chiral liquid crystalline compounds, (S)-[4-n-alkyloxy-benzoyloxyphenyl]-4′-[(2-n-alkyloxy)propionyloxy] benzoate (QMn/m), were synthesised. Polymorphism of the new compounds was investigated by polarising microscopy and differential scannin
- Vajda, Aniko,Kaspar, Miroslav,Hamplova, Vera,Pakhomov, Ser-Gei A.,Vanek, Premysl,Bubnov, Alexei,Fodor-Csorba, Katalin,Eber, Nandor
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p. 569 - 580
(2007/10/03)
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- The synthesis and mesomorphism of di-, tetra- and hexa-catenar liquid crystals based on 2,2′-bipyridine
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2,2′-Bipyridines are known to coordinate to a wide variety of metal centres. In this paper, liquid-crystalline two-chained (dicatenar), four-chained (tetracatenar) and six-chained (hexacatenar) bipyridines are synthesised and their mesomorphism is described. For the tetracatenar bipyridines, a full homologous series, from tetramethoxy to tetratetradecyloxy, was synthesised, and the phase diagram showed a classic progression from nematic and smectic C phases at short chain length, through a cubic phase to a columnar phase.
- Rowe, Kathryn E.,Bruce, Duncan W.
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p. 331 - 341
(2007/10/03)
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- 1,1'-Disubstituted Ferrocene-Containing Thermotropic Liquid Crystals of Structure 5-C5H4)COOC6H4XC6H4OCnH2n+1>2> (X=OOC or COO). Influence of the Orientation of the Central Ester Function on the Mesogenic Properties
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The two series I and II of 1,1'-disubstituted ferrocenes which differ by the direction of the ester function included the rigid organic part were synthesized and their liquid crystal properties examined.These latter were found to be strongly dependent on the orientation of the connecting ester group and on the alkyl chain.
- Deschenaux, Robert,Marendaz, Jean-Luc,Santiago, Julio
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p. 865 - 876
(2007/10/02)
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- Optically active compound having XI-valerolactone ring and liquid crystal composition comprising same
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An optically active compound having a δ-valerolactone ring which is a ferroelectric liquid crystal and is represented by the following general formula (I): STR1 wherein m is an integer of from 1 to 8, Z is a group represented by the following formula: STR2 in which each of l and k is a number of 1 or 2 and l and k satisfy the requirement of 2≤(l+k)≤3, X stands for a direct bond, STR3 Y stands for STR4 and A1 and A2 independently stand for --H, --F or --Cl, STR5 R stands for STR6 in which n is an integer of from 1 to 18, and * indicates the asymmetric carbon atom.
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- Mesomorphic compound having β-hydroxycarboxyl group as chiral source and liquid crystal composition
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Disclosed is a mesomorphic compound having a β-hydroxycarboxyl group as the chiral source, which is represented by the formula: STR1 wherein m and n are integers of from 1 to 18, X1 and X2 independently represent fluorine, chlorine or hydrogen, Y represents STR2 or --O--, Z represents a direct bond, STR3 --CH hd 2O-- or --OCH2 --, and * indicates the asymmetric carbon. The mesomorphic compound is valuable as a ferroelectric liquid crystal or an additive to a ferroelectric liquid crystal or to a compound showing the SmC phase and having no chiral group.
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- FERROELECTRIC SC* PHASE IN SOME BENZOATE SERIES
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Several homologous benzoate series which exhibit ferroelectric smectic SC* phases have been synthesized.The used chiral acid chains were prepared from commercially available α-amino acids.The series allow us to determine the influence of the size of the substituent of the chiral carbon on the existence and the stability of the SC* phase.They also give some compounds or mixtures which display high spontaneous polarization.
- Tinh, Nguyen Huu,Salleneuve, C.,Babeau, A.,Galvan, J. M.,Destrade, C.
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p. 147 - 154
(2007/10/02)
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