Synthesis and characterization of homologous series with chiral (S)-1-methylpropyl terminal substituent

Homologous series of liquid crystalline azoesters and azomethine esters consisting of a (S)-1-methylpropyl group attached in one of the terminal positions have been synthesized and thermally characterized. All twenty-four derivatives from both series, namely, the 4-(4-n-alkoxybenzoyloxy)-4'-1-(S)-methylpropylazobenzenes and 4-(4-n-alkoxybenzoyloxy)benzylidene-4'-1-(S)-methylpropylanilines exhibit mesomorphism. The lower members of the homologous series show a chiral nematic phase while the higher members show smectic C*, smectic A as well as chiral nematic mesophases. The homologues have been characterized using IR, NMR and UV-Visible, spectroscopies, X-ray diffraction and DSC. Their mesomorphic properties are compared with those of structurally related homologous series.     

Synthesis and configuration of diastereomeric 2-substituted 5-oxoquinuclidines

The individual diastereomers of 5-oxoquinuclidine-2-carboyxlic acid and its methyl ester and of 2-benzoyloxymethyl-5-oxoquinuclidine were obtained, and their stereochemistry and assignment to the quinine and quinidine series were given on the basis of the PMR spectra.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1665–1671, December, 1971.     

Synthesis and characterization of two isomeric liquid crystal series with reactive double bonds

Two series of potentially cross-linkable liquid crystal materials derived from p-phenylenebisacrylic (series I, n(P.FB.P), n = 2-10) and p-hydroxycinnamic acid (series II, n(HC.T.HC), n = 2-10) have been synthesized and their thermal and mesomorphic properties studied. All these compounds show enantiotropic mesomorphism over a wide range of temperatures. Compounds with short terminal chains are nematic and when the terminal chain length is increased they show smectic polymorphism-smectic A and C. Most of the compounds are thermally stable over their mesophase ranges.     

Synthesis and characterisation of two homologous series of LC acrylic monomers based on phenolic and resorcinic azobenzene groups

The synthesis and phase characterisation of two homologous series of monomers of acrylic azo-compounds has been presented. The characterisation comprises polarising optical microscopy (POM), differential scanning calorimetry (DSC) and powder X-ray diffractometry (PXRD). All studied monomers exhibit a narrow nematic phase with decrease in temperature range while increasing the alkoxy tail length. For the resorcinic azo benzenes at higher tail lengths, SmA and SmC phases are present. Phenolic azo compounds show only SmA phase. The resorcinic family showed more stable phases, with broader liquid crystalline temperature range than its phenolic equivalent.     

High pressure phase diagrams of two homologous series of Inotropics

The hexagonal-isotropic transition is studied in two homologous series of lyotropic liquid crystals. The high pressure phase diagrams are mapped up to 2 kbar for three homologues from each of the Triton X and Triton N series of non-ionic surfactants. We find that an interesting hexagonal-isotropic re-entrant phenomenon is a common feature of the transition lines of homologues in each series. For each homologue in each series, we report a systematic increase in the average value of dP/dT with decreasing concentration correlated with the presence of the re-entrant phenomenon.     

High pressure phase diagrams of two homologous series of Inotropics

Abstract

The hexagonal-isotropic transition is studied in two homologous series of lyotropic liquid crystals. The high pressure phase diagrams are mapped up to 2 kbar for three homologues from each of the Triton X and Triton N series of non-ionic surfactants. We find that an interesting hexagonal-isotropic re-entrant phenomenon is a common feature of the transition lines of homologues in each series. For each homologue in each series, we report a systematic increase in the average value of dP/dT with decreasing concentration correlated with the presence of the re-entrant phenomenon.     

Synthesis of two naphthyl-containing homologous series of mesogenic ligands and the related metallomesogens containing Cu(II)

Two new naphthyl-containing homologous series of mesogenic ligands, the 4-n-alkoxy-2-hydroxybenzylidene-2'-naphthylamines (series I) and 4(4'-n-alkoxybenzoyloxy)-2-hydroxybenzylidene-2'-naphthylamines (series II), as well as the related metallomesogens of higher homologues containing a Cu(II) atom, have been synthesized. All the ligands and complexes were characterized by a combination of elemental analysis and standard spectroscopic methods. In series I, n-heptyloxy and n-octyloxy derivatives are non-mesogenic whereas the remaining higher members synthesized exhibit a monotropic nematic mesophase. In series II, all the members synthesized exhibit an enantiotropic nematic mesophase. All the metallomesogens of series I synthesized exhibit a monotropic smectic A mesophase, except for the n-octyloxy derivative, which is non-mesogenic, whereas metallomesogens of series II exhibit enantiotropic nematic mesophases up to the n-tetradecyloxy derivatives; the n-tetradecyloxy and n-hexadecyloxy derivatives also exhibit smectic C mesophases. All the members of series II and their metallomesogens exhibit mesophases with wide temperature ranges and greater thermal stability as compared to series I and their metallomesogens, respectively. The mesomorphic properties of both the present series and their metallomesogens are compared with each other and with other structurally related series to evaluate the effect of the naphthalene moiety on mesomorphism.     

Synthesis and mesomorphic behaviours of a homologous series of 2-(4-alkyloxybenzylidenamino)benzothiazoles

The synthesis and characterisation of a series of new rod-shaped liquid crystal (LC), 2-(4-alkyloxybenzylidenamino)benzothiazoles possessing even number of carbon atoms at the alkyloxy chain (C_nH_2n?+?1O-, n = 2, 4, 6, 8, 10, 12, 14, 16, 18) are reported. The molecular structures of title compounds were elucidated using FTIR and nuclear magnetic resonance spectroscopic techniques. The phase behaviour of these new compounds was characterised and studied by differential scanning calorimetry and polarising optical microscopy. Lower members (n = 2, 4 and 6) did not exhibit mesophase. Octyloxy derivative was monotropic LC. Enantiotropic smectic A phase was observed from n-decyloxy derivatives onward to the last homologous synthesised.     

Synthesis of two diastereomeric C1-C22 fragments of spirastrellolide A

The optimisation of a synthetic strategy towards the ABC segment of the cytotoxic macrolide spirastrellolide A is reported, together with its application to the synthesis of two diastereomeric C(1)-C(22) fragments for stereochemical correlation purposes with a putative spirastrellolide degradation product.     

Synthesis and transformations of polysubstituted diastereomeric 5-oxomorpholin-2-carboxylic acids

A series of trans- and cis-3,4-disubstituted 5-oxomorpholine-2-carboxylic acids 5 were prepared by a cyclocondensation between diglycolic anhydride 3 and arylideneamines 4. Transformations of the carboxylic group leading to a peptide bond in the side chain to the morpholinone ring were effected. The relative configurations and the preferred conformations of the substituents at the morpholinone ring in some of the newly prepared derivatives were determined by means of ¹H NMR and X-ray analysis.     

Synthesis and characterization of two series of pressure-sensitive cholesteric liquid crystal elastomers with optical properties

ABSTRACT

We synthesized two series of cholesteric liquid-crystal elastomers by hydrosilylation among monomers MA containing a cholesteryl group, MB (MC) containing a phenolic hydroxyl group and MD as the crosslinker. The chemical structures of all the monomers and LCEs were confirmed by ¹H NMR and FT-IR. We explored the mesomorphic properties and phase behaviours by TGA, DSC, POM, and XRD. All the LCEs presented elasticity, reversible phase transition, and high thermal stability. For two series of LCEs, the glass transition temperature increased slowly, and the isotropic transition temperature increased obviously. PA-I-PA-V and PB-I-PB-IV displayed selective reflection and colourful Grandjean texture, but PA-VI, PB-V, and PB-VI needed external pressure to show them.     

Synthesis of diastereomeric ketoconazole analogs

Syntheses of trans-isomers of ketoconazole, and the corresponding des-acetyl, 1-methyl-, 1-formyl and 1-methanesulfonyl analogs were investigated. These isomers, along with the corresponding cis-diastereomers were characterized by their carbon-13 nmr spectra.     

Odd-even behavior of ferroelectricity and antiferroelectricity in two homologous series of bent-core mesogens

Two chiral bent-core mesogens Pn-O-PIMB(n - 2)* (n = 9 and 10) and their oxygen analogues Pn-O-PIMB(n - 2)*-(n - 4)O (n = 8, 9, and 10) with omega-[(S)-amyloxy]alkoxy terminal groups were prepared, and their phase structures were investigated by means of electro-optic, polarization reversal current and second harmonic generation measurements in order to clarify the effect of the interlayer steric interaction on the emergence of polar orderings. The odd-even behavior for the alternative appearance of ferroelectricity and antiferroelectricity was observed in two homologous series; the bent-core mesogens P10-O-PIMB8*, P8-O-PIMB6*-4O, and P10-O-PIMB8*-6O in addition to the previously reported P6-O-PIMB4* and P8-O-PIMB6*, where the length of chains n is even, exhibited ferroelectric phases. On the contrary, the mesogens P7-O-PIMB5*, P9-O-PIMB7*, and P9-O-PIMB7*-5O, where n is odd, showed antiferroelectric phases. It is obvious that the interlayer steric interaction plays a major role for the emergence of a variety of phase structures.     

Synthesis of diastereomeric trianglamine-β-cyclodextrin-[2]-catenanes

The synthesis of novel diastereomeric [2]-catenanes derived from β-cyclodextrin and an enantiomeric trianglamine is described using a [3+3] cyclocondensation reaction.     

Synthesis and stability of a homologous series of triynol natural products and their analogues

A series of polyyne natural products 1, 13, and 31 and analogues 14, 21, and 22 are synthesized in six steps. The key step is a Fritsch-Buttenberg-Wiechell rearrangement in which a triyne framework is formed from the appropriate dibromoolefin precursor. Terminal conjugated triynes 13 and 14 are obtained as highly unstable products that rapidly decompose under ambient conditions. The stability of triynols increases via either the addition of methylene units (i.e., 6 --> 31 --> 1) or addition of terminal substituents (i.e., 13 --> 21 or 31).     

Synthesis and characterization of a series of modified polyacrylamide

We present the synthesis and the characterization of a new class of modified polyacrylamides (MPAM) with the unusual trait of strong emulsification ability, viscosity enhancement capacity, and significant salt tolerance. Besides, the synthesized polymers have the peculiar aggregation behaviors in aqueous solution. The synthesis was carried out by polymerizing the monomers such as acrylamide (AM), acrylic acid (AA), unsaturated amphiphilic functional moieties, and high steric hindrance functional units. Their aggregation behaviors were investigated by using a scanning electron microscope (SEM). The emulsion, formed by 10 ml of MPAM (with the polymer concentration of 1,000 mg/L) and the 10 ml of crude oil, was very stable, which indicates that the synthesized polymers have unique emulsification properties. The strong hydrophobic interaction between molecules and the three-dimensional network formed in aqueous solution were exhibited by the experimental results of steady fluorescence and SEM experiments. It could be concluded that the performance of polymers for enhanced oil recovery (EOR) can be remarkably enhanced by introducing functional monomers to polymer backbone, which allows the new class of modified polymers to have more promising application in enhanced oil recovery.     

Synthesis and characterization of a series of homooligopeptide peroxyesters

A homologous series of stable N(alpha)-phthaloyl peptide peroxyesters based on alpha-aminoisobutyric acid residues was prepared. In each of the six oligomers synthesized, the chain of alpha-amino acids is separated from the peroxyester function by a beta-amino acid. [structure: see text]     

两个噻吩并萘并吡喃类化合物的合成及结构表征

以2,7-萘二酚为原料分别经六步反应合成了两个新的角型噻吩并萘并吡喃化合物6和8。两个目标化合物及所有新中间体的结构均经^1HNMR、MS、IR、元素分析充分表征。测定了化合物6的单晶分子结构,其特殊的分子平面刚性和α-吡喃与噻吩部分的活泼双键间的空间结构使之成为更有效的单官能团DNA嵌入剂。     

Synthesis and phase behaviour of a homologous series of polymethacrylate-based side-chain liquid crystal polymers

The homologous series of side chain liquid crystal polymers, the poly[ω-(4-methoxyazobenzene-4′-oxy)alkyl methacrylate]s, has been prepared in which the length of the flexible alkyl spacer has been varied from 3 to 11 methylene units. All the polymers exhibit liquid crystalline behaviour. The propyl and butyl members show exclusively nematic behaviour. The pentyl, hexyl, octyl and decyl members show a nematic and a smectic A phase while the heptyl, nonyl and undecyl homologues exhibit only a smectic A phase. The smectic A phase has been studied using X-ray diffraction and assigned as a smectic A₁ phase in which the side chains are fully overlapped and the backbones are confined to lie between the smectic layers. For the nonyl member an incommensurate smectic phase is observed. The dependence of the transition temperatures on the length of the flexible spacer is understood in terms of the average shapes of the side chains.