Mesogenic 4-alkoxy-2-hydroxy-4’-formylazobenzenes

Homologous 4-alkoxy-2-hydroxy-4’-formylazobenzenes (Alk = C₃H₇, C₆H₁₁, C₈H₁₇) were synthesized and were shown to produce monotropic nematic liquid crystalline phase. The products were characterized by electron absorption and ¹H and ¹³C NMR spectra. The effect of lateral hydroxy group on their mesomorphic properties was analyzed.     

The effect of olefinic terminal chains on the mesomorphic properties of 4,4′-disubstituted diphenyldiacetylenes

New diphenyldiacetylenes of the type with A, B = H and/or F; m = 0, 1; n = 1–4; and X = C _n H_2n+1, F, CF₃ or CN were synthesized and their mesomorphic properties determined by hot stage polarizing microscopy and DSC. When m = 0, all of these compounds showed only a nematic phase except when X = CF₃ when both nematic and smectic A phases were seen. Both clearing and melting temperatures were higher than those reported for substitution with the corresponding alkyl chains but the much larger increase in clearing temperatures produced considerably wider nematic phases. Eutectic mixtures of a few of these olefins yielded nematic materials also having much wider temperature ranges and higher clearing temperatures than the eutectic mixtures of the alkyl compounds, while retaining their high birefringence and low viscosities. Such materials are of interest for beam-steering devices. Four of the diacetylenes with m = 1 (A, B = H) were also prepared (X = C₆H₁₃, F, n= 2, 3). When X was C₆H₁₃ (n=2), the nematic range was smaller in the 2- than in the 1-olefin but wider than in the alkyl series. When X=F, either no nematic phase or a monotropic one was observed, whereas the 1-olefins gave a much wider nematic phase. Both transition temperatures were lower than those for the corresponding 1-olefin and alkyl analogues. The compound with X=C₆H₁₃ and n=2 had a melting temperature below room temperature.     

Shape‐Assisted Self‐Organization in Highly Disordered Liquid Crystal Phases

In achiral rod‐like molecules, a nematic phase is the most disordered liquid crystal phase, which only has one‐directional order in the direction of the molecular long axis. A dumbbell‐shaped molecule (compound 3 : R−C₆H₁₀−CH=CH−C₆H₄−CH=CH−C₆H₁₀−R, (R=n C₅H₁₁)), and its liquid crystal phase (X phase) are reported, which exhibit high scattering without thermal fluctuation between two nematic phases under a polarized light optical microscope. The X phase was investigated by X‐ray diffraction, scanning electron microscopy, atomic force microscopy, and molecular dynamics simulation. A layered structure was ascertained for which a molecular self‐organization mechanism was postulated in which the super‐structure is based on lateral intermolecular interlocking. A second nematic phase above the X phase consisted of “rice grain”‐shaped particles.     

Water-Soluble Polymeric Complexes of Cobalt(II) and Nickel(II) with Azolate Anions

N-Unsubstituted azoles (1,2,4-triazole, 3-amino-1,2,4-triazole) and 5-R-tetrazoles (R = H, CH₃, C₂H₅, C₄H₉, CH = CH₂, C₆H₅, p-CH₃C₆H₄, NH₂) form water-soluble polymeric complexes in systems containing certain transition metal salts. The data obtained and the results of MP2/6-31G^{* *} calculations of the electronic structures of 5-R-tetrazolate anions show that the ability of azoles for formation of polymeric complexes with transition metal ions is mostly determined by the acid-base properties of azoles. The geometric structure of a polymeric chain with the Co²⁺ ion having the coordination number 6 and the 5-methyltetrazolate anion being a bridging ligand was examined at the STO-3G level. It was shown that the coordination by the 2- and 3-nitrogen atoms of the tetrazole ring is most favored by energy.     

Reduction of α,β unsaturated carbonyl compounds by Ni–BH4

The reduction of α,β unsaturated carbonyl compounds by sodiumborohydride is catalysed by Ni(bpy)Cl₂ (bpy=2,2′-bipyridine). Various carbonyl compounds having the general formula R₁CH=CHCRO [where R₁, R=C₆H₅, H; p-MeO---C₆H₄---,C₆H₄; p-CH₃---C₆H₄, C₆H₅; (m-OMe---)(p-OMe---)C₆H₃, C₆H₅; C₆H₅, (CH₃)₂CH---; CH₃, H; m-Br---C₆H₄---, C₆H₅] are reduced to corresponding allylicalcohol [R₁CH=CHCRHOH] at 25°C within half an hour. During these reductions the double bond is partially reduced to give saturated alcohols as minor products having the molecular formula R₁CH₂CH₂CRHOH. The reduction of trans-3-phenyl-2-propenal with NaBH₄ and catalytic amounts of Ni(bpy)Cl₂ in solvents containing active deuterium (D₂O, CD₃OD), leads to the partial incorporation of deuterium at the α and γ positions to give C---D bonded alcohols.     

The nematic-isotropic two phase region in mixtures of quasi-spherical solutes in alkylcyanobiphenyls: An E.S.R. study using tempone as probe

The transitional behaviour of binary mixtures, each containing a non-mesomorphic quasi-spherical solute at a low mole fraction in a nematogenic solvent, has been investigated by E.S.R. spectroscopy using 4-oxo-2,2,6,6-tetramethyl-4-piperidinyl-1-oxy (tempone) as a spin probe. This approach makes use of the smaller coupling constant obtained for the spin probe in the orientationally ordered nematic phase relative to that obtained in the isotropic phase. The solutes included Et₄C (tetraethylmethane) and R ₄Sn (R = C^b2bH₅, n-C_{3 H 7} and nC_b4H₉). The solvents were 4-n-pentyl-4′-cyanobiphenyl (5CB) 4-n-hexyl-4′-cyanobiphenyl (6CB) and 4-n-heptyl-4′-cyanobiphenyl (7CB). This fast approach compares favourably with other studies. In addition it provides the tempone spectral parameter, f, which is a relative measure of the fraction of the nematic phase at different temperatures within the two phase region.     

Theoretical Investigations on Fluorine-Substituted Ethylene Dications C2HnF4-n 2+(n = 0–4)

The optimized geometries and energies of fluorine-substituted ethylene dications C₂H_nF_4-n ²⁺ (n = 0–4) have been investigated by means of ab initio methods. At the MP3/6-31G**//6-31G* + zero-point energy level of theory, the results predict that C₂F₄²⁺ and C₂HF₃²⁺ are planar, while C₂H₄²⁺, C₂H₃F²⁺ and 1,1—C₂H₂F₂²⁺ prefer a perpendicular geometry. For 1,2—C₂H₂F₂²⁺ an energy difference of only 0.3 kcal/mol is found between the (trans) planar and perpendicular structure. The stabilizations attributed to hyperconjugation, fluorine lone-pair donation, and (C? F) double-bond conjugation are discussed. A comparison is made for the C? C and C? F stretching frequencies determined at 6-31G*//6-31G* between the neutral and dicationic species. The theoretically determined ionization energies for the vertical process N⁺ → N²⁺ at the MP3/6-31G*//3-21G level are compared with experimental Q_min values.     

Synthesis,characterization and in vitro antitumor activity of some arylantimony ferrocenecarboxylates and crystal structures of C5H5FeC5H4CO2SbPh4 and (C5H5FeC5H4CO2)2Sb(4‐CH3C6H4)3

A series of arylantimony ferrocenecarboxylates with the formula (C₅H₅FeC₅H₄CO₂)_nSbAr_(5?n) (n = 1, 2; Ar = C₆H₅, 4‐CH₃C₆H₄, 3‐CH₃C₆H₄, 2‐CH₃C₆H₄, 4‐ClC₆H₄, 4‐FC₆H₄) were synthesized and characterized by elemental analysis, IR, ¹H NMR and mass spectra. The crystal structures of (C₅H₅FeC₅H₄CO₂)₂Sb(4‐CH₃C₆H₄)₃ and C₅H₅FeC₅H₄CO₂SbPh₄ were determined by X‐ray diffraction. Four human neoplastic cell lines (HL‐60, Bel‐7402, KB and Hela) were used to screen these compounds. The results indicate that these compounds at 10 µM show certain in vitro antitumor activities. Copyright © 2003 John Wiley & Sons, Ltd.     

Synthesis and liquid crystalline behavior of a series of ferrocene 1,1′-bis-azino-derivatives

A series of liquid-crystalline ferrocene derivatives, Fe{C₅H₄-C(CH₃)=N-N=CH-C₆H₃(X)-OOC-C₆H₄-OC _n H_2n+1}₂ (X = H, OH;n = 3 to 12), were obtained by the condensation of 1,1 -bishydrazondiacetylferrocene withp-alkoxybenzoyloxybenzaldehides. According to DSC and polythermic microscopy, all of the compounds exhibit an enantiotropic nematic mesophase in the 150–230 °C temperature range. A polycrystalline transition precedes the nematic transition. The liquid crystalline properties of the obtained compounds were investigated with respect to the number of carbon atoms in the terminal alkyl chain and the terminal hydroxyl group. The composition and structure of the obtained compounds were determined by elemental analysis and IR and NMR spectroscopy.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 358–361, February, 1995.This work was carried out with financial support from the Russian Fundation for Basic Research (Project No. 94-03-08978).     

Synthesis of liquid crystal ferrocene derivatives and their complexes with Cu2+

A series of liquid crystal ferrocene-containing Schiff bases of general formula C₅H₅FeC₅H₄-C₆H₄-N=CN-(X)C₆H₃-O(O)-C₆H₄-OC_nH_2n+1 (X=H, OH, n=3–12) was obtained, together with several analogs, 1,1-bis-substituted at the ferrocene fragment, having a thermotropic nematic mesophases. Derivatives with X=OH were used to obtain Cu²⁺ chelate complexes, of which the compounds with n=10 and n=12 displayed nematic liquid crystalline properties.Physicotechnical Institute, Kazan Scientific Center, Russian Academy of Sciences, 420083 Kazan. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 2, pp. 402–407, February, 1992.     

Quantum-Chemical Study of Electronic and Steric Structure of Vinyltetrazoles: I. 2-Substituted 5-Vinyltetrazoles

The total Mulliken charges on the carbon atoms of the vinyl group, populations of S-trans-(N¹)conformers, and internal rotation energies were calculated ab initio (HF/6-31G**, MP2/6-31G**, and MP2/6-31G**//AM1) for a series of 2R-5-vinyltetrazoles (R = CH₃, C₂H₅, i-C₃H₇, t-C₄H₉, C₆H₅). The calculation results were compared to the available experimental data.     

Synthesis and mesomorphic properties oftrans-[1,4-bis(5-R-pyrimidin-2-yl]-cyclohexanes and 1,2-bis-(5-R-pyrimidin-2-yl)ethanes

New trans-bis(5-R-pyrimidin-2-yl)-1,4-cyclohexanes and-1,2-ethanes (R=C₇H₁₅, C₆H₄OR¹, where R¹=H, COCH₃, C₄H₉, C₅H₁₁, C₈H₁₇) have been synthesized. Only nematic mesophases are found from a study of their mesomorphic properties, except for bis[5-(4-octyloxyphenyl)- and-(4-acetoxyphenyl)pyrimidin-2-yl)-cyclohexanes, which also exhibit smectic properties.Novosibirsk Institute of Organic Chemistry of the Siberian Division of the Russian Academy of Sciences, Novosibirsk 630090, Russia; e-mail: benzol@nioch.nsc.ru. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 355–360, March, 1999.     

Rate constants for the elementary reactions between CN radicals and CH4, C2H6, C2H4, C3H6, and C2H2 in the range: 295 ⩽ T/K ⩽ 700

Pulsed laser photolysis, time-resolved laser-induced fluorescence experiments have been carried out on the reactions of CN radicals with CH₄, C₂H₆, C₂H₄, C₃H₆, and C₂H₂. They have yielded rate constants for these five reactions at temperatures between 295 and 700 K. The data for the reactions with methane and ethane have been combined with other recent results and fitted to modified Arrhenius expressions, k(T) = A′(298) (T/298)ⁿ exp(?θ/T), yielding: for CH₄, A′(298) = 7.0 × 10^?13 cm³ molecule^?1 s^?1, n = 2.3, and θ = ?16 K; and for C₂H₆, A′(298) = 5.6 × 10^?12 cm³ molecule^?1 s^?1, n = 1.8, and θ = ?500 K. The rate constants for the reactions with C₂H₄, C₃H₆, and C₂H₂ all decrease monotonically with temperature and have been fitted to expressions of the form, k(T) = k(298) (T/298)ⁿ with k(298) = 2.5 × 10^?10 cm³ molecule^?1 s^?1, n = ?0.24 for CN + C₂H₄; k(298) = 3.4 × 10^?10 cm³ molecule^?1 s^?1, n = ?0.19 for CN + C₃H₆; and k(298) = 2.9 × 10^?10 cm³ molecule^?1 s^?1, n = ?0.53 for CN + C₂H₂. These reactions almost certainly proceed via addition-elimination yielding an unsaturated cyanide and an H-atom. Our kinetic results for reactions of CN are compared with those for reactions of the same hydrocarbons with other simple free radical species. © John Wiley & Sons, Inc.     

有玻璃态和液晶态的胆甾烯基苯并菲的合成及介晶性

将盘状液晶基元苯并菲与手性向列型液晶基元胆甾烯基结合的化合物, 可望出现全新的性质. 合成了含有胆甾烯基的苯并菲化合物C₁₈H₆(OC₅H₁₁)₅(OC₅H₁₀COOCh) (2), 2,7-C₁₈H₆(OC₅H₁₁)₄(OC₅H₁₀COOCh)₂ (4), C₁₈H₆(OR)₃(OC_nH_{2nCOO- Ch)3 (R＝C5H11, C7H15, C9H19, C11H23, n＝1, 5, 10) (6a～6f), C18H6(OC5H10COOCh)6 (Ch: cholesteryl) (8). 偏光显微镜和差示扫描量热法对这些化合物的热致介晶性研究结果显示, 化合物 4, 6a～6e具有手性盘状向列相和玻璃态, 8呈现近晶B相(SB)和玻璃态. 随间隔基长度n和烷基链R碳原子数的增加, 化合物玻璃化温度和清亮点呈下降趋势. 随着胆甾烯基数目减少, 化合物的玻璃化温度和清亮点降低.}     

Liquid-crystalline CuII and PdII complexes with nonmesogenic ferrocene-containing β-aminovinyl ketone

New liquid-crystalline heteropolynuclear complexes L₂M (M=Cu²⁺ (2a), Pd²⁺ (2b)) were synthesized by the reactions of C₅H₅FeC₅H₄−C₆H₄NH−C₂H₂−(CO)−C₆H₄OC₁₂H₂₅ (1, LH) with copper(ii) and palladium(ii) acetates. Compound2b was found to possess monotropic nematic and smectic phases;2a exhibits the monotropic nematic phase and a phenomenon of “double melting”. The compositions and structures of compounds1 and2a,b were established by elemental analysis,¹H and¹³C NMR, ESR, and IR spectroscopy. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 381–383, February, 1999.     

Bowl-shaped hydrocarbons related to C60

Ab initio studies at the HF/6-31G* and B3LYP/6-31G* levels are reported for two bowl-shaped hydrocarbons related to C₆₀: C₃₀H₁₂ and C₃₆H₁₂, of C₃ and C_3v symmetry, respectively. The former has an approximate heat of formation of 211 kcal/mol. Bowl-to-bowl interconversion may occur through a planar (C_3h) form of ca. 64 kcal/mol greater energy having one imaginary vibrational frequency. The larger C₃₆H₁₂ bowl has a calculated ΔH°_f of 265 kcal/mol. Its HF/6-31G*, B3LYP/6-31G*, and MM3 bond lengths are in good agreement with a recent X-ray structure. Chemical shifts for both compounds calculated by the GIAO method are in good agreement with the measured NMR spectra. The observed ¹³C chemical shifts increase with the extent of pyramidalization. © 1998 John Wiley & Sons, Inc. J Comput Chem 19: 189–194, 1998     

Crystal Structures of [Mn2(H2O)4(phen)2(C4H4O4)2] · 2 H2O and [Mn(phen)2(H2O)2][Mn(phen)2(C4H4O4)](C4H4O4) · 7 H2O

Reactions of 1,10‐phenanthroline monohydrate, Na₂C₄H₄O₄ · 6 H₂O and MnSO₄ · H₂O in CH₃OH/H₂O yielded a mixture of [Mn₂(H₂O)₄(phen)₂(C₄H₄O₄)₂] · 2 H₂O ( 1 ) and [Mn(phen)₂(H₂O)₂][Mn(phen)₂(C₄H₄O₄)](C₄H₄O₄) · 7 H₂O ( 2 ). The crystal structure of 1 (P1 (no. 2), a = 8.257(1) Å, b = 8.395(1) Å, c = 12.879(2) Å, α = 95.33(1)°, β = 104.56(1)°, γ = 106.76(1)°, V = 814.1(2) ų, Z = 1) consists of the dinuclear [Mn₂(H₂O)₄(phen)₂(C₄H₄O₄)₂] molecules and hydrogen bonded H₂O molecules. The centrosymmetric dinuclear molecules, in which the Mn atoms are octahedrally coordinated by two N atoms of one phen ligand and four O atoms from two H₂O molecules and two bis‐monodentate succinato ligands, are assembled via π‐π stacking interactions into 2 D supramolecular layers parallel to (101) (d(Mn–O) = 2.123–2.265 Å, d(Mn–N) = 2.307 Å). The crystal structure of 2 (P1 (no. 2), a = 14.289(2) Å, b = 15.182(2) Å, c = 15.913(2) Å, α = 67.108(7)°, β = 87.27(1)°, γ = 68.216(8)°, V = 2934.2(7) ų, Z = 2) is composed of the [Mn(phen)₂(H₂O)₂]²⁺ cations, [Mn(phen)₂(C₄H₄O₄)] complex molecules, (C₄H₄O₄)^2– anions, and H₂O molecules. The (C₄H₄O₄)^2– anions and H₂O molecules form 3 D hydrogen bonded network and the cations and complex molecules in the tunnels along [001] and [011], respectively, are assembled via the π‐π stacking interactions into 1 D supramolecular chains. The Mn atoms are octahedrally coordinated by four N atoms of two bidentate chelating phen ligands and two water O atoms or two carboxyl O atoms (d(Mn–O) = 2.088–2.129 Å, d(Mn–N) = 2.277–2.355 Å). Interestingly, the succinato ligands in the complex molecules assume gauche conformation bidentately to chelate the Mn atoms into seven‐membered rings.     

Molecular dynamics in the nematic,SA and SC phases of 8S5 and 9S5 as studied by dielectric methods

Abstract

Two experimental techniques—time domain spectroscopy (TDS) and a steady state frequency method—have been used to study dielectric spectra for the isotropic, nematic, S_A, S_C and S_Y phases of two thioesters (4-n-pentylphenyl-4′-n-octyloxy-and 4′-n-nonyloxythiobenzoates (C _n H_2n+1 O?C₆ H₄?COS?C₆H₄?C₅H₁₁, where n = 8 and n = 9) known as 8S5 and 9S5, in the frequency range from 10 Hz to 10 GHz. In the case of 8S5 a deuteriated sample (8S5-d ₂₈) has been used to study relaxation processes in the nematic and smectic phases.     

Organometallic chiral liquid crystals: bis{4-[ω-(cholest-5-en-3-yloxycarbonyl)alkoxy]phenylethynyl}mercury complexes

We report the synthesis and thermal behaviour of the first chiral organometallic trimesogens having bis[(4-phenyl)ethynyl]mercury as the central core connected on either side to cholesteryl ester moieties through either even-even (C₄) or odd-odd (C₃, C₅ and C₇) central alkylene spacers. All the organomercury trimesogens exhibit a chiral nematic phase. These mercury complexes are extremely sensitive to heat, in a manner reminiscent of other reports.     

Influence of the smectic A-nematic transitional order on the formation of the smectic phases of 4-n-hexyloxybenzylidene-4′-n-butyIaniline and 4-n-butyloxybenzylidene-4′-n-octyIaniline from an electrically deformed nematic phase

Abstract

The crucial role of the smectic A-nematic transitional order for the formation of the smectic A, B and G phases from an electrically deformed nematic phase of the liquid crystal 4-n-hexyloxy-benzylidene-4′-n-butylaniline (6O.4) with a typical smectic A-nematic first order transition and the formation of the smectic A and B phases from an electrically deformed nematic phase of the liquid crystal (4-n-butyloxy-benzylidene-4′-n-octylaniline (40.8) with a smectic A-nematic second order transition has been demonstrated. The nematic phase was deformed by an AC voltage of 2U,_th 5U _th and 10U _th, where U _th is the threshold voltage which causes the appearance of the Fréedericksz transition in the homeotropic nematic layer. The smectic textures have been observed on free cooling of the nematic phase or after the use of an oven. The smectic A phase of the liquid crystal 60.4 was observed with the formation of a clear smectic A-nematic phase boundary while the smectic A phase of the liquid crystal 40.8 has been formed from intermediate pretransitional stripes, observed by Cladis and Torza [1]. The homeotropic anchoring of the direction was crucial for the formation of the smectic phases of the liquid crystal 40.8 but not significant for the liquid crystal 60.4.