Liquid Crystal Complexes Research Articles

Induction of Liquid Crystalline Phases and Influence of Chain Length of Fatty Acids in Linear Hydrogen-Bonded Liquid Crystal Complexes

A novel series of linear hydrogen-bonded liquid crystals (HBLCs), viz., Py14BA:nFAs synthesized from nonmesogenic moieties, such as an N(p-n-pyridene carboxaldehyde), p-n-tetradecyl aniline, and the long-chain-bearing aliphatic acids (nFAs for n = 10, 12, 14, 16, and 18), are reported. The chemical stability, purity of the sample, and the presence of hydrogen bonding (HB) are confirmed by polarized thermal microscopy and 1H NMR and IR spectroscopy. The LC phase abundance is characterized by polarized optical microscopy (POM) and differential scanning calorimetry (DSC) techniques. Py14BA:nFAs are found to exhibit BF liquid crystalline phase variance. The Iso–SmBcryst and SmBcryst–SmF transitions are found to be of first-order nature. Phase diagram for Py14BA:nFAs infers the induction and enhancement of LC phase stability. The growth of tilted LC phases due to HB interaction is discussed. Analysis of the influence of chain length (n) on LC phase stability, viz., ΔTLC and ΔTTilt, suggests for a tunable molecular pair potential given by U12(n) = [A × eαn − 1]. The tilted LC phase stability is found to grow with a relative exponential strength in Py14BA:nFA series.

Synthesis and Mesomorphic Properties of Two Series of Hydrogen-Bonded Liquid Crystals Based on Laterally Fluorinated Benzoic Acid and 4, 4′-Bipyridine With a Molar Ratio of 2:1

Two series of hydrogen-bonded liquid crystal complexes have been obtained from binary mixtures of 4, 4′-bipyridine and 2-fluoro-6-X-4-alkoxybenzoic acids (where X = H or F) with a molar ratio of 2:1. The fluorinated proton donors were synthesized firstly and then their chemical structures measured by EA, FTIR, 1H NMR and 13C NMR. The existences of hydrogen bonds between the proton donors and acceptors were identified by FTIR. The liquid crystalline properties of these complexes were investigated by differential scanning calorimeter (DSC), polarizing optical microscopy (POM), and X-ray diffraction (XRD). The results indicated that these complexes with different alkoxy chains and numbers of lateral fluorine atoms exhibited different phase properties. Especially, when the alkoxy chains were short enough, the mesophase of the complexes disappeared.

Mesogenic and Luminescent Properties of Lyotropic Liquid Crystals Containing Eu(III) and Tb(III) Ions

Lyotropic metallomesogens containing trivalent rare-earth metal ions have unique attractive behavior due to the combination of some specific properties of the lanthanide ions with anisotropic supramolecular organization liquid crystal and provide new promises in biochemistry and materials science. In this article, we have studied the liquid crystal and luminescence properties of lyotropic systems containing Eu(III) and Tb(III) ions based on nonionic surfactants. The type, the structural parameters of the mesophases, and the structure of a liquid crystal complex have been investigated using polarized optical microscopy (POM), X-ray diffraction, and Fourier transform infrared. In addition, on the basis of the luminescence lifetime, the structure of the first coordination sphere was determined. The results obtained based on time-resolved spectroscopy data are discussed in the light of the influence ligand environment, ion type, and the type of supramolecular organization on the luminescence efficiency of lyotropic lanthanide containing systems. The first time was reported for Eu(III) complexes increasing the luminescence efficiency in the hexagonal phase compared to the lamellar mesophase.

Synthesis and optical behaviour of hydrogen-bonded liquid crystals based on a chiral pyridine derivative

Three series of cholesteryl-containing supramolecular hydrogen-bonded (H-bonded) liquid crystal (LC) complexes with different number of fluoro-substituent were synthesised and characterised. Cholesteryl isonicotinate as proton acceptor and 4-n-alkoxybenzoic acids with or without fluoro-substituent as proton donor had been mixed in tetrahydrofuran to obtain H-bonded LC complexes. The effect of lateral substitution and the length of terminal chain in the H-bonded precursors on the formation of the supramolecular complexes had been examined. It was found that the introduction of fluoro substituent on the induced mesogens could widen the molecular width and thus reduce the molecular aspect ratio of the complexes, therefore it could lead to compress the formation of the LCs. However, the fluoro substituent played a positive role in enhancing the intermolecular interactions and stabilising the H-bond structure of the complexes. The influence of terminal length on the mesogenic behaviours is also discussed. On increasing the spacer length, the clear point and the thermal range of induced mesophase-like cholesteric phase decreased, and an induced chiral smectic phase began to appear in some complexes with long terminal tails.

Supramolecular Liquid Crystals Induced by Intermolecular Hydrogen Bonding

A series of new hydrogen-bonded liquid-crystal complexes formed between para-substitued alkoxybenzoic acids (OBAm, where m denotes the number of the carbon in the alkoxy group, m = 4, 5, 6, 7, 8, 10) and 4′-pyridylazophenyl-4-alkoxybenzoate (PEAPn, where n represents the number of the carbon in the alkoxy group, n = 5, 6, 7 8, 10, 12, 14, 16) have been investigated by Fourier transform infrared (FTIR) Spectroscopy, differential scanning calorimetry (DSC), Polarizing optical microscopy (POM), and variable-temperature X-ray diffraction analysis. All PEAPn themselves are smectic mesogens and the hydrogen-bonded complexes show entiotropic smectic phases. The hydrogen bonding can raise the clear points of the complexes and, at the same time, decrease the melting points. The complexes were found to possess a much wider mesophase range than their corresponding individual components. The influence of the terminal chain lengths of OBAm and PEAPn on the phase transition temperatures is discussed. The results indicate that mostly the mesogenic behavior of the hydrogen-bonded assemblies exhibits a slight odd–even effect.

Tris(β-diketonates) lanthanum nematic adducts

A series of new liquid-crystalline adducts of lanthanum tris(β-diketonates) displaying nematic and smectic mesomorphism was synthesised and investigated. The temperatures and thermodynamic parameters of the phase transitions were determined. Even–odd alternation of the nematic–isotropic transition was observed in the series of synthesised complexes. It was found that films of the obtained liquid-crystal complexes are vitrified when cooling, and packings of molecules, formed in the mesophase, are retained. Interlayer distances were determined and a model of packing of molecules in the mesophase was suggested based on data obtained by a small-angle X-ray scattering method.

Enhancement of the Kerr response in polymer-dispersed liquid crystal complexes due to incorporation of BiB3O6 nanocrystallites

Abstract We have established a substantial enhancement of Kerr coefficients for 1150 nm cw He–Ne laser wavelength using BiB 3 O 6 (BiBO) nanocrystallites (NC) incorporated into polymer-dispersed liquid crystal composites (PDLC). For this reason we have used 3% and 5.2% in weighting units of BiBO NC possessing sizes varying within the 60–90 nm. It was discovered that BiBO NC may be used for effective gain of Kerr electro-optical susceptibilities varying by the content of the NC at T = 77 K. Moreover, an increase of the Kerr coefficients correlates with decreasing dc-current under applied voltage. The maximally achieved value of the Kerr coefficients were equal to about 1.2·10 − 9 m V − 2 ( λ = 1150 nm) corresponding to BiBO content equal to about 3%. Such polymer nanocomposites may be considered as perspective materials for the electro-optical Kerr modulators.

Kerr modulators based on polymer-dispersed liquid crystal complexes

We have demonstrated a possibility to design light modulator based on Kerr effect using borate La2CaB10O19 (LCBO) nanocrystallites incorporated into two different polymer-dispersed liquid crystal composites (PDLC). For this reason we have used different amount of the LCBO nanocrystallites to find the optimal conditions for the Kerr modulators. It was established that for the both PDLC systems the borate nanocrystals may be used for effective operation by elecrooptical susceptibilities varying the content of the nanocrystals. At the same time the frequency shift of the Kerr coefficient seems to be sensitive only for the LCBO nanocrystals content about 5% by weight. The maximal value of the Kerr coefficients were varied within the 4 × 10−9 to 6 × 10−10 m V−2.

Supramolecular Hydrogen-Bonded Liquid Crystals Formed from 4-(4′-Pyridylazophenyl)-4″-alkoxy Benzoates and 4-Substituted Benzoic Acids

Four pyridine-based derivatives (I 10, I 12, I 14, and I 18) with molecular formula CnH2n+1O-C6H4COOC6H4-N = N-C5H4N, that differ from each other in the number of carbon atoms, n, were prepared and characterized for their mesophase behavior. The number of carbons in the alkoxy chain varies between 10, 12, 14, to 18 atoms, respectively. Liquid crystalline properties were studied for two series of hydrogen-bonded liquid crystal complexes, consisting of the central 4-pyridylazophenyl benzoate and substituted benzoic acids. In the first series of the supramolecular complexes (group A), the lengths of the alkoxy chains on both of the azo pyridine and the benzoic acid components have varied between 10, 12, 14, and 18 carbons. In the second series (group B), the same proton-acceptors, i.e., the pyridyl azo derivatives, were used but with benzoic acids para-substituted with small compact polar groups, X. All of the newly prepared pyridine-based derivatives and their hydrogen-bonded complexes were found to be mesomorphic. The newly prepared pyridine-based derivatives and their supramolecular complexes in both groups were characterized for their mesophase behavior by differential scanning calorimetry, DSC, and polarized light microscopy, PLM. Four 4-alkoxybenzoic acids (CmH2m+1OC6H4COOH, II 10, II 12, II 14, and II 18) were used in group A series; the number of carbons (m) of their alkoxy groups also varies between 10, 12, 14, and 18, respectively. Substituents on the other group of acids (III a−f) in group B series vary, respectively, between CH3O, CH3, H, Br, CN, and NO2. Smectic C mesophase is induced in most of the binary mixtures investigated.

Symmetric bi-pyridyl banana-shaped molecule and its intermolecular hydrogen bonding liquid-crystalline complexes

A new symmetric bi-pyridyl banana-shaped molecule 1,3-phenylene diisonicotinate (PDI) was designed and synthesized. Its molecular structure was confirmed by FTIR, Elemental analysis and 1H NMR. X-ray crystallographic study reveals that there is an angle of approximate 118° among the centroids of the three rings (pyridyl–phenyl–pyridyl) in each PDI molecule indicating a desired banana shape. In addition, a series of liquid crystal complexes nBA:PDI:nBA induced by intermolecular hydrogen bonding between PDI (proton acceptor) and 4-alkoxybenzoic acids (nBA, proton donor) were synthesized and characterized. The mesomorphism properties and optical textures of the complex of nBA:PDI:nBA were investigated by differential scanning calorimetry, polarizing optical microscope and X-ray diffraction.

Influence of hydrogen bonding on phase abundance in ferroelectric liquid crystals

The synthesis and characterization of five hydrogen-bonded ferroelectric liquid crystal complexes (HBFLCs) prepared from mesogenic p-n-alkoxy benzoic acids and non-mesogenic propionic/butyric acids with different chiral centres are reported. Complementary intermolecular hydrogen bonding is confirmed through IR study. HBFLCs are found to exhibit chiral nematic (N*), smectic C* (SmC*) and smectic G* (monotropic) phases in their cooling profiles during polarizing thermal microscopy and differential scanning calorimetry. Phase coexistence regions are observed above the IN* transition. The chiral nematic to smectic C* transition is found to be of first order. The temperature variation of spontaneous polarization exhibited by these HBFLC complexes in their SmC* phase is presented. The effect of non-covalent interaction imparted by the soft hydrogen bonding in these LC complexes on enhanced or induced thermal stability of tilted LC phases is discussed.

Induced Crystal-G Phase through Intermolecular Hydrogen Bonding Part XIV: Influence of Alkyl Carbons of p-Hydroxybenzoates on Phase Distribution of Induced Phase

Two novel series of intermolecular hydrogen-bonded liquid crystal complexes resulting from equimolar combinations of p-n-alkoxybenzoic acids (nABA) (where n represents alkoxy carbon numbers 3 to10 and 12) and non-mesogens viz. ethyl-p-hydroxybenzoate (EHB) and propyl-p-hydroxybenzoate (PHB) have been synthesized. The formation and stabilization of the hydrogen bonding is confirmed by infrared spectral study, which reveals the terminal functionalities, -COOH and -OH moieties are complementary to each other by acting as both proton donor and acceptor. The results of comparative thermal and phase analyses of both the series are discussed in conjunction with free- p-n-alkoxybenzoic acids. The induction of crystal-G phase with wide thermal spans is observed in the present complexes.

Emulsifying potency of new amino acid-type surfactant (II): stable water-in-oil (W/O) emulsions containing 85 wt% inner water phase.

The ternary phase diagram for N-[3-lauryloxy-2-hydroxypropyl]-L-arginine L-glutamate (C12HEA-Glu), a new amino acid-type surfactant, /oleic acid (OA)/water system was established. The liquid crystal and gel complex formations between C12HEA-Glu and OA were applied to a preparation of water-in-oil (W/O) emulsions. Stable W/O emulsions containing liquid paraffin (LP) as the oil and a mixture of C12HEA-Glu and OA as the emulsifier were formed. The preparation of stable W/O emulsions containing 85 wt% water phase was also possible, in which water droplets would be polygonally transformed and closely packed, since the maximum percentage of inner phase is 74% assuming uniformly spherical droplets. Water droplets would be taken into the liquid crystalline phase (or the gel complex) and the immovable water droplets would stabilize the W/O emulsion system. The viscosity of emulsions abruptly increased above the 75 wt% water phase (dispersed phase). The stability of W/O emulsions with a lower weight ratio of OA to C12HEA-Glu and a higher ratio of water phase was greater. This unusual phenomenon may be related to the formation of a liquid crystalline phase between C12HEA-Glu and OA, and the stability of the liquid crystal at a lower ratio of oil (continuous phase). W/O and oil-in-water (O/W) emulsions containing LP were selectively prepared using a mixture of C12HEA-Glu and OA since the desirable hydrophile-lipophile balance (HLB) number for the emulsification was obtainable by mixing the two emulsifiers.

Synthesis, Characterization of Cu(II) and Ni(II) Liquid Crystal Complexes of an Unsymmetrical β-Diketone Containing a Terminal Double Bond

The unsymmetrical β-diketone-type ligand [H(DK-11-12)] containing a terminal double bond derived from 4-dodecyloxy-acetophenone (A) and methyl 4-undecenyloxybenzoate (B) and its complexes [M(DK-11-12)2] (M = Cu, Ni) were synthesized and characterized by elemental analyses, molar conductivity, IR, electronic spectra, 1H NMR and magnetic susceptibility measurements. The ligand functions as an uninegative bidentate and bonds through the two oxygen atoms of the cw-enol moiety. The two complexes are non-electrolytes and have square-planar geometry. The mesogenic behaviors of the β-diketone-type ligand and the complexes were determined via a combination of observation on a hot-stage polarized microscope and DSC measurements. The ligand has no liquid crystallinity. The complexes are liquid crystals whose mesogenic textures are a type of broken-fan. The transition processes of the complexes were tentatively proposed to be K→S→I.

Palladium-catalyzed condensation of symmetrical diaryliodonium salts with phenylacetylene in aqueous media

liarities of the effect observed for birefringence (the non-quadratic dependence of the effect, exceeding the molecular effect by 4 orders of magnitude), note that it is proportional to the magnetic anisotropy of supramolecular structures AZ, at least a weak magnetic field. The molar constants of the effect of magnetic birefringence 3 mP 0 ~ AczAz approximated to a zero magnetic field are equal to 6.3 9 10 -11, 7.3 9 10 -11, 1.5.10 -7 cm 3 mo1-1 for La, Gd and Dy derivatives, respectively. The similar chemical properties of rare-earth ions, along with the IR and N M R data for solutions and for the condensed phase suggest that the solutions of the complexes studied have the same structure, and, hence, the same anisotropy of electronic polarizability (Am) of their objects. Thus the ratio of the anisotropy for the magnetic susceptibilities of the associates, and, in the approximation of axial symmetry, of the remaining complexes (AXm) is approximately equal to the ratio of the mP 0 constants: AXm(La)/AXm(Gd)/AXm(DY ) = 1/1.2/2.4" 103 . Analogous results were obtained for solutions of the complexes in chloroform and benzene. The liquid crystal complexes of diamagnetic lanthanum and paramagnetic (S = 7/2, Pelf = 7.9 M.B.) gadolinium (in S state), which have similar compositions and structures, possess magnetic anisotropy typical of mesogenes. The paramagnetic complex of Dy is characterized by magnetic anisotropy, significantly exceeding the anisotropy of known organic and metal-containing mesogenes.

Liquid-crystal complexes of some lanthanides with a nonmesogenic ?-enaminoketone

Liquid-crystal complexes of some lanthanides with a nonmesogenic ?-enaminoketone

Isomorphous mixing of mesogenic anions and uncharged analogues in organised poly(ehtylene oxide)‐alkali salt complexes

AbstractThe preparation and characterisation of novel ionic polymer liquid crystal complexes of poly(ethylene oxide)–Na+ with mesogenic anions and their uncharged structural analogues in homogeneous mixtures are described. The systems discused most fully are the anion of the phenolic mesogen 4‐n‐hexyloxybenzylidene‐4‐hydroxy aniline (1) with its uncharged analogue 4‐n‐hexyloxybenzylidene aniline (1a) and the anion of 5‐(4‐n‐octyloxy‐2,3‐dicyanophenyleneoxycarbonyl)benzimidazo‐le (2) and its uncharged analogue 4‐octyloxy‐2,3‐dicyanophenyloxybenzoyl (2). Differential scanning calorimetry, wide angle x‐ray diffraction and polarised light microscopy show that PEO–Na1/1a and PEO–Na2/2a are homogeneous mesogenic phases when Na1 or Na2 are present at 50% or less of the stoichiometric composition in complexes (EO : salt = 3 : 1) and the shortfall is made up from 1a or 2a uncharged analogues of 1a and related systems substituted by methoxy rather than hydrogen do not form homogeneous mixtures.

Paramagnetic liquid crystal complex of iron(III) with a schiff base

Chloro-bis[dodecyliminomethyl-(4-heptyloxybenzoyloxv-4'-phenyl-2-olate)]iron. A solution of 0.178 g (1.1"10 -3 mole) anhydrous FeCI 3 in ethanol was added to an ethanolic solution of 1.086 g (2.10 -a mole) dodecyliminomethyl-(4-heptyloxybenzoyloxy-4'-phenyl-2-ol) at 650C. The mixture was cooled. The red-brown crystalline precipitate formed was filtered off, washed with cold ethanol, and dried in vacuum to give 0.7 g (60%) product. IR spectrum (v, cm -I, vaseline): 1605 (C----N), 1725 (C----O). Found: C 69.70; H 8.48; N 2.39; CI 3.23; Fe 4.98%. Calculated for Cs6H96CIFeOsN2: C 69.75; H 8.98; N 2.47; CI 3.13; Fe 4.93%.

Iridium liquid crystal complexes by co-ordination of non-mesogenic orgainic ligands

The first family of iridium liquid crystal complexes [lrCl(CO)2L](L = NC5H4–CHN–C6H4R) formed by complexation of a non-mesogenic organic ligand directly to the metal is described.

ChemInform Abstract: LIQUID‐CRYSTAL COMPLEXES OF COPPER WITH SCHIFF BASES

Chemischer InformationsdienstVolume 16, Issue 15 Organoelement Compounds ChemInform Abstract: LIQUID-CRYSTAL COMPLEXES OF COPPER WITH SCHIFF BASES YU. G. GALYAMETDINOV, YU. G. GALYAMETDINOVSearch for more papers by this authorI. V. OVCHINNIKOV, I. V. OVCHINNIKOVSearch for more papers by this authorB. M. BOLOTIN, B. M. BOLOTINSearch for more papers by this authorN. B. ETINGEN, N. B. ETINGENSearch for more papers by this authorG. I. IVANOVA, G. I. IVANOVASearch for more papers by this authorL. M. YAGFAROVA, L. M. YAGFAROVASearch for more papers by this author YU. G. GALYAMETDINOV, YU. G. GALYAMETDINOVSearch for more papers by this authorI. V. OVCHINNIKOV, I. V. OVCHINNIKOVSearch for more papers by this authorB. M. BOLOTIN, B. M. BOLOTINSearch for more papers by this authorN. B. ETINGEN, N. B. ETINGENSearch for more papers by this authorG. I. IVANOVA, G. I. IVANOVASearch for more papers by this authorL. M. YAGFAROVA, L. M. YAGFAROVASearch for more papers by this author First published: April 16, 1985 https://doi.org/10.1002/chin.198515312Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume16, Issue15April 16, 1985 RelatedInformation