Synthesis of new mesogenic compounds having the isoflavone core group

Two new series of calamitic liquid crystals containing the isoflavone moiety within the central core have been prepared and their liquid crystalline properties studied. The compounds exhibit typical nematic, smectic A and C mesophases. The influence of the linking group between a terminal alkyl chain and the central core has been proven to determine the variety of mesomorphism displayed by the compounds.     

甲基取代的聚芳醚酮酮酰亚胺树脂的合成与性能

N,N′-(4,4′-二苯甲烷)-二偏苯三甲酰亚胺酰氯(DIDC-M)与4,4′-二(2-甲基-苯氧基)三苯二酮(o-Me-DPOTPDK) 进行低温溶液共缩聚,制备了甲基侧基取代的聚芳醚酮酮酰亚胺(o-Me-PEKKI)聚合物.用FT-IR,1H-NMR,DSC,TG 和WAXD对聚合物的结构和性能进行了表征.研究表明:聚合物为非晶态结构;具有较高的玻璃化转变温度(Tg:241 ℃)和较好的耐热性能(Td:487 ℃);能溶解于间甲酚、NMP、氯仿、四氯乙烷等有机溶剂中.     

Synthesis and curing behavior of alkyl-substituted poly(aryl ether ketone)s having a crosslinkable styryl group at chain ends

Crosslinkable alkyl-substituted poly(aryl ether ketone)s (PEKs) bearing a styryl group at both chain ends were synthesized by nucleophilic substitution reaction of 1,1′-(p-phenyl-enedioxy)bis[2-methyl-4-(4-fluorobenzoyl)benzene] with an excess aromatic diol in the presence of a base, followed by the reaction of the terminal phenol group with chloromethylstyrene. The aromatic diols used in this study were hydroquinone and resorcinol. The molecular weight of the polymer determined by GPC and ¹H NMR agreed with each other and close to the theoretical value calculated from the feed ratio. The polymer was soluble in N,N-dimethylacetamide and tetrahydrofuran, but insoluble in acetone and methanol. From DSC analysis, the polymer was thermally crosslinked around 220°C. The addition of dicumyl peroxide as a radical generator in the polymer decreased the curing temperature. The cured polymer showed high thermal stability up to 420°C under nitrogen. © 1997 John Wiley & Sons, Inc.     

Synthesis and photochromism of photochromic spiro compounds having a reactive pendant group

The photochromic spiropyrans and spirooxazines having a reactive pendant group, including carboxyl, halide, succinimidyl ester and isothiocyanate, were synthesized. Their photochromic behaviors in solution and solid state were studied.     

Main chain thermotropic polyesters having flexible spacers—influence of ester group linking order between mesogenic unit and flexible spacer

Two series of main chain thermotropic polyesters having a decamethylene spacer were prepared and their thermal transitions and liquid crystalline properties were studied. The linking sequence of the ester bond between the mesogenic unit and spacer, i.e., versus with M and S being mesogenic unit and spacer, respectively, was found to influence profoundly the nature of the mesophase formed by the polymers. The former favors the formation of a smectic phase, while the latter favors the formation of a nematic phase. The structure of the central dicarboxylic acid moiety of the triester mesogenic units also was found to influence greatly the polymer's ability to form mesophases.     

由2-(1, 3-亚丙二硫基)亚甲基脂环酮出发合成共轭的烯酮硫缩醛

2-(1, 3-亚丙二硫基)亚甲基脂环酮(2')与甲基、丁基、仲丁基Grignard试剂经1, 2-加成反应得产物3, 3在酸的催化下脱水生成共轭的烯酮硫缩醛类化合物4。本实验提供了一条经由α-羰基烯酮环二硫代缩醛类化合物合成在有机合成中有重要应用的共轭烯酮硫缩醛类化合物的新途径。     

Two-photon absorption properties of azulenyl compounds having a conjugated ketone backbone

Two-photon absorption (TPA) properties of newly synthesized conjugated ketone derivatives that include nonalternant azulenyl moieties in the pi-conjugation system, alpha,alpha'-bis(1-azulenylidene)cyclopentanone (1Az), alpha,alpha'-bis(2-azulenylidene)cyclopentanone (2Az), and alpha,alpha'-bis(6-azulenylidene)cyclopentanone (6Az) are reported. TPA spectra of these azulenyl compounds were measured using the open-aperture Z-scan method with a femtosecond laser. The TPA cross section at the peak position (sigma(2)peak) of 1Az was found to be the largest among the three azulenyl compounds, which is almost 7 times larger than that of the alpha,alpha'-bis(1-naphthylidene)cyclopentanone (1Nph), an alternant isomer of 1Az with the same number of pi-electrons. The small detuning energies of the azulenyl compounds compared to those of 1Nph were responsible for the large TPA cross sections. We report that a compound having an azulenyl moiety can be a promising TPA material.     

Synthesis of optically active organoantimony compounds having an (S)-alpha-methylbenzyldimethylamine group and its evaluation for asymmetric reaction

Novel, enantiomerically pure organoantimony compounds having a C-chiral amine moiety, (S)-(alpha-methyl-2-di-p-tolylstibanobenzyl)dimethylamine [AMSb] (2) and its (eta(6)-arene)chromium complex [AMSb-Cr(CO)(3)] (4), were prepared from common (S)-(alpha-methylbenzyl)dimethylamine (1) via its ortho-lithiated intermediates in short steps. The catalytic activity and enantioselectivity of the ligands 2 and 4 for asymmetric reaction are evaluated, and the optically active (eta(6)-arene)chromium complex 4 has been shown to be an effective ligand for rhodium-catalyzed asymmetric hydrosilylation of ketones.     

Synthesis and characterization of side-chain liquid-crystalline poly(ether ester)s having p-substituted biphenyl mesogenic side groups

Several novel mesogenic spiro-orthoester monomers such as 1,6,10-trioxaspiro[4,5]decanes 4 , containing biphenyl mesogens at the C-8 positions of the five- and six-membered spirocyclic ring, through the alkylene spacers of different lengths were prepared by condensation reaction of the corresponding biphenyl mesogenic 1,3-propanediol 3 with 2,2-diethoxytetrahydrofuran, with 50–75% yields. Through cationic double ring-opening polymerization, carried out with boron trifluoride etherate as an initiator (5 mol % vs. monomer) in bulk at 150°C, spiro-orthoester monomers 4 afforded a novel class of side-chain thermotropic LC polymers with a poly(ether ester) as the main chain 8 . The liquid-crystalline properties of the spiro-orthoester monomers and the resulting polymers were examined by differential scanning calorimetry and optical polarized microscopy. Biphase separation was observed in the side-chain liquid-crystalline poly(ether ester)s upon annealing in the broad isotropic region. © 1998 John Wiley & Sons, Inc. J. Polym. Sci. A Polym. Chem. 36: 2439–2455, 1998     

Synthesis of 4,6-bis(1H-1,2,3-triazolyl)pyrimidines by the reaction of 4,6-diazido-2-(4-methoxyphenyl)-pyrimidine with compounds containing a reactive methylene group

The reaction of 4,6-diazido-2-(4-methoxyphenyl)pyrimidine with cyanoacetic ester in the presence of triethylamine leads only to 4-azido-6-amino-1-(4-methoxyphenyl)pyrimidine. The main product in reactions with 1,3-dicarbonyl compounds (acetylacetone, acetoacetic and benzoylacetic esters) is the corresponding substituted 4,6-bis(1H-1,2,3-triazolyl)pyrimidine. The formation of 4-azido-6-(1H-1,2,3-triazolyl)pyrimidine and 4-amino-6-(1H-1,2,3-triazolyl)pyrimidine as minor products was also recorded.Novosibirsk Institute of Organic Chemistry, Siberian Branch, Russian Academy of Sciences, Novosibirsk 630090. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 8, pp. 1109–1114, August, 1997.     

Synthesis and characterisation of imidazolium-based ionic liquid crystals bearing a cholesteryl mesogenic group

A series of cholesteryl-containing imidazolium chlorides and imidazolium tetrachloroaluminates were synthesised, and the chemical structure, liquid crystalline behaviour and ionic conductivity were characterised by several technical methods. Whereas the imidazolium chlorides show chiral smectic A (SmA*) phase on heating and cooling cycles, the imidazolium tetrachloroaluminates display chiral nematic (N*) phase, which is uncommon for ionic liquid crystals (ILCs). The imidazolium chlorides display similar phase transition temperature and entropy, indicating the cholesteryl component influence predominately on the phase transition rather than the different alkyl substituent groups. The imidazolium tetrachloroaluminates show lower melting point temperatures and lower clear point temperature than the imidazolium chlorides. The mesophases exist at rather moderate temperatures. Non-mesomorphic imidazolium tetrachloroaluminate(III) salts with short alkyl substituents have been known for a long time, and the synthesised imidazolium tetrachloroaluminates are the first examples of tetrahalogenoaluminate(III)-containing ILCs. For the imidazolium tetrachloroaluminates, imidazolium cations combine loosely with AlCl₄^? ions because AlCl₄^? ions are large and occupy more space in spite of the hydrogen bond and electrostatic attraction interaction, indicating that the layer structure can be destroyed easily to form N* phase on heating.     

聚醚醚酮醚酮的合成与表征

聚醚醚酮（ＰＥＥＫ）自工业化以来［１］，由于其优异的性能已在机械、航天等领域得到广泛应用．各种聚芳醚酮类聚合物相继被开发出来．但以亲电缩聚路线制备聚醚醚酮醚酮（ＰＥＥＫＥＫ）的报道较少［２］．本文以二苯醚和４－氟苯甲酰氯为主要反应试剂，采取付氏酰基化...     

含氟聚醚醚酮酮的制备及其性能

以邻氟对苯二酚和4,4′-二氟三苯二甲酮为原料通过亲核缩聚反应,合成含氟聚醚醚酮酮(FPEEKK)材料。 用FTIR、1H NMR和WAXD进行了结构表征,用DSC、TGA测试了热性能,并研究了聚合物的溶解性、吸水性、介电性能及光学性能。 结果表明,含氟聚醚醚酮酮具有较好的热性能（N2气气氛中,5%热分解温度为505 ℃）;能溶于氯仿、四氢呋喃和N,N-二甲基甲酰胺等有机溶剂;具有较低的吸水率(0.24%)和介电常数（ε=3.0）;在近红外区1300和1550 nm处吸收非常弱。     

Synthesis and mesomorphic properties of chiral liquid crystals derived from (S)-2-(6-hydroxy-2-naphthyl)propionic acid with a methyleneoxy linking group

Three homologous series of chiral materials derived from (S)-2-(6-hydroxy-2-naphthly)propionic acid with a methyleneoxy linking group were synthesized for the investigation of mesomorphic properties. All the materials displayed enantiotropic SmA* and SmC* phases. The spontaneous polarization (P _s) and optical tilt angles in the SmC* phase of the chiral materials were measured. The maximum spontaneous polarizations are in the range 12.3-19.1 nC cm^-2. No significant difference could be found in the P _s values with respect to the various alkyl chiral chain lengths, n. The maximum optical tilt angles are in the range 25-30°. The optical tilt angles decrease with the increase in alkyl chain length, n.     

Synthesis, characterization and crystal structures of two polyphilic mesogenic compounds

Three homologous series of semi-perfluorinated liquid crystals: 4-(2,2,3,3,4,4,4-heptafluoro-butyloxycarbonyl)phenyl, 4-(2,2,3,3,4,4,5,5-octafluoropentyloxycarbonyl)phenyl and 4-(3,3,4,4,5,5,6,6,7,7,8,8,8-tridecafluorooctyloxycarbonyl)phenyl 4-[(n-perfluoroalkyl)alkyloxy]benzoates have been synthesized. Their mesomorphic properties were studied by DSC, microscopic observation and X-ray diffraction. Their layer spacings are smaller than the molecular length (L). The ratio d_SA/L is about 0.7. The crystal structure of two derivatives of the first family have also been investigated. In both structures the molecules pack in smectic C-like sheets where neighbouring molecules are antiparallel, interacting through dipolar and van der Waals forces. The interactions between contiguous sheets, through the ends of perfluorinated chains are very weak. The X-ray diffraction results on the mesophases and on the crystalline structures of two compounds of the first family are compared. From this, we propose a model of the smectic phases with a zig-zag structure.     

Synthesis and properties of mesogenic laterally fluorinated compounds containing benzoxazole unit

Series of mesogenic laterally fluorinated compounds, 2-(2′,3′-difluoro-4′-alkoxybiphenyl-4-yl)-benzoxazole derivatives (nB-Fx) bearing different substituents (H, CH₃, Cl, NO₂, coded as nB-FH, nB-FM, nB-FC and nB-FN, respectively) at 5-position, were prepared and characterised. Their phase transition behaviour was investigated by differential scanning calorimetry and polarising optical microscopy. nB-Fx with alkoxy chain lengths of 2 to 10 carbons exhibited enantiotropic mesophases, for which the mesophase ranges were 0°C–58°C and 0°C–71°C on heating and cooling for nB-FH, 41°C–93°C and 66°C–140°C for nB-FM, 44°C–133°C and 87°C–155°C for nB-FC, and 0°C–76°C and 0°C–95°C for nB-FN, respectively. Compared to non-fluorinated analogues, with the exception of nB-FC, fluorinated nB-Fx mainly exhibited nematic mesophase both in heating and cooling, which were attributed to the disruption of the side-to-side intermolecular packing caused by the two ortho-lateral fluoro substituents. For nB-Fx series, nB-FM, nB-FC and nB-FN exhibited a much wider mesophase range than the corresponding nB-FH series, which indicated that the substituent at benzoxazole moiety was helpful in increasing the mesophase stability. With the exception of nB-FN, the nB-Fx series displayed intense photoluminescence emission at 379–383 nm in methylene chloride solution, when it was excited at its absorption maxima.