Synthesis and Phase Behavior Studies of Two New Chiral Liquid Crystals of Schiff Base——The Influence of Intramolecular Hydrogen Bond on the Phase Behavior

Two new chiral liquid crystals of schiff-base type have been synthesized.This series of compounds contain α-chloro acidic ester chain prepared from commercially available L-valine.Both of the compounds exhibit tilted smectic phases;their phase transitions were studied using DSC and polarized optical microscopy;the influence of intramolecular hydrogen bonds on the phase behavior was studied as well.

Synthesis and Crystal Structure of Complex of Zinc(Ⅱ) with Schiff Base {Zn[CH_3O(O)-C_6H_3CH_3=NN=C(S)NH_2](DMF)}_2

The title complex is a new binuclear Zn(Ⅱ) with chelate ligand of Schiff base containing S and N atom.The complex crystallizes in the orthorhombicspace group Pccn,with a=12.338(9),b=16.666(8),c=17.503(6),V=3599(6),Mr=723.52,Z=4,Dx=1.34 g/cm3,μ=15.22 cm-1,F(000)=1488.The structure was solved by direct methods and the final R=0.078.The crystal consists of discrete molecules with symmetric center at the center of the fourmembered ring consisting of two Zn atoms and two O atoms.

Synthesis and characterization of lanthanide complexes containing a bulky tridentate [N,N,O] Schiff base ligand

The lanthanide complexes containing a bulky tridentate [N,N,O] Schiff base ligand 3,5-But2-2-（OH）C6H2CH=N-8-C9H6N （HL） were synthesized and characterized. The reaction of anhydrous LnCl3 with NaL formed in situ in a 1：1 molar ratio in THF at room temperature afforded the lanthanide Schiff base dichloride complexes LnLCl2（DME） （Ln=Eu （1）; Sm （2））. Complexes 1 and 2 can be used as precursors for the synthesis of the lanthanide cyclopentadienyl Schiff base derivatives. The reactions of complexes 1 and 2 with one equiv of NaCH3C5H4 in THF provided the desired products LnL（CH3C5H4）CI（THF）.THF （Ln=Eu （3）; Sm （4）） in good isolated yields. These complexes were characterized by elemental analysis, IR spectra, and X-ray structural determination, in the case of complexes 3 and 4. The crystal data of complex 3 are monoclinic, P21/C space group, a=1.3370（2） nm, b=1.5190（2） nm, c=1.8910（3） nm, β=109.846（4）°, V=3.6125（8） nm^3, Z=4, Dc=1.416 mg/m^3,μ=1.847 mm^-1, F（000）=1584, R=0.0707, wR=0.1350. The crystal data of complex 4 are monoclinic, P21/c space group, a=1.3383（1） nm, b=1.5210（2） nm, c=1.8960（2） nm, β =109.878（3）°, V=3.6293（7） nm^3, Z=4, Dc=1.407 mg/m^3, μ=1.728 mm^-1, F（000）= 1580, R=0.0670, wR=0.1385.

Synthesis and Crystal Structure of a Salicylaldehyde Ethylene Diamine Schiff Base Manganese (Ⅲ) Complex

The title compound, [Mn(salen)(salicyl)]?.5H2O ( H2salen = N, N?ethylenebis- (salicylideneaminato), Hsalicyl = salicylaldehyde), has been obtained from the reaction system containing (o-HOC6H4CH=NCH2)2, o-HOC6H4CHO and Mn(ClO4)2?H2O in EtOH solvent and structurally characterized. It crystallizes in the monoclinic, space group P21/c with a = 13.0548(4), b = 13.9254(4), c = 11.6630(1) ? b = 105.199(2)? V = 2046.09(9) ?, Z = 4, C23H22MnN2O5.5, Mr = 469.37, Dc = 1.524 g/cm3, F(000) = 972, m = 0.687mm-1 . R = 0.0630 and wR = 0.1142 for 1901 observed reflections with I >2(I). The Mn(Ⅲ) is coordinated by N(1), N(2), O(1) and O(2) of the Schiff base ligand and phenolate O atom of salicylaldehyde with O(3)Mn distance of 2.050(4) , forming a relatively rare five-coordinate square-pyramidal structure.

Synthesis and Crystal Structure of a New 2D O-bridged Copper(Ⅱ) Coordination Polymer Constructed from Sulfonate-derived Schiff Base

A new chain-like coordination polymer, namely, [CuL]n （1, Na2L = 2-[（2-hydroxy- benzylidene）-amino]-benzenesulfonic acid sodium salt）, has been synthesized and characterized by single-crystal X-ray diffraction, IR spectroscopy and elemental analysis. Complex 1 crystallizes in monoclinic system, space group P21/c with a = 9.2296（16）, b = 10.4754（18）, c = 12.200（2） A, β = 102.392（2）°, V = 1152.0（3）A3, CI3H9CuNOaN, Mr = 338.83, Dc = 1.953 g/cm3, Z = 4, F（000） = 684, p = 2.089 mm-1, the final R = 0.0376 and wR = 0.0956. X-ray diffraction analyses indicate that 1 displays a square-pyramidal metal center with NO4 donor sets. The sulfonate-derived Schiff base serves as a common N,O,O＇-tridentate and a unique O-bridged ligand connecting the metals. Dinuclear copper complexes serve as secondary building blocks （SBUs） to construct an unusual 2D coordination network. In the crystal, the components form a stable 3D supramolecular architecture by C-H...O interactions and to-stacking

Synthesis and Crystal Structures of Schiff Bases Bearing Ferrocenylphenyl Groups

The Schiff bases bearing ferrocenylphenyl and diferrocenylphenyl groups were synthesized by the reactions of m-ferrocenylaniline with salicylaldehyde or 1, 4-bis (2′-formyl- phenyl)-1, 4-dioxabutane. The title compounds were characterized by elemental analysis, IR, 1H NMR and X-ray structural determination.

Synthesis and Crystal Structure of a Di-μ_2-phenolic Bridged Binuclear Manganese(Ⅲ) Schiff Base Complex

A new complex [Mn（L）（NCS）]2·0.5CH3CN （H2L = N,N＇-bis（chlorosalicylidene）-1,2-diaminoethane） has been synthesized,and its structure （C70H51Cl8Mn4N13O8S4,Mr = 1833.84） was determined by single-crystal X-ray diffraction analysis. The crystal belongs to the monoclinic system,space group C2/c with a = 25.883（2）,b = 12.3320（13）,c = 13.5951（16） ,β = 112.906（2）,V = 3997.2（7） 3,Z = 2,Dc = 1.524 g/cm3,μ（MoKα） = 1.050mm-1,F（000） = 1852,S = 1.098,the final R = 0.0630 and wR = 0.1847 for 2542 reflections with Ⅰ 〉 2σ（Ⅰ）. The centrosymmetric title complex contains a dimer in which two distorted octahedral Mn（Ⅲ） centers are bridged equatorially by phenolic oxygen of the Schiff base ligand. The units of the complex are linked via weak C-H···N hydrogen bonds,leading to the formation of 1D chains along the b axis. The weak π-π packing interactions and weak intermolecular C（3）-H（3）···N（3） hydrogen bonds stabilize the crystal structure.

Synthesis and Crystal Structure of Lanthanide Schiff Base Complex [2-OC_6H_4CHN(2,6-i-Pr_2C_6H_3)]_2ErCl(THF)

The lanthanide Schiff base complex [2-OC6H4CHN(2,6-i-Pr2C6H3)]2ErCl(THF) (C42H52ClErN2O3) has been prepared by the reaction of anhydrous LnCl3 with 2 equiv. of the sodium salt of the bidentate Schiff base N-(2,6-diisopropylphenyl)salicylaldimine in THF. The crystal structure was determined by X-ray diffraction analysis. The crystal belongs to triclinic, space group P1 with a = 9.200(1), b = 13.637(2), c = 16.705(2) ? a = 74.493(7), b = 77.979(8), g = 81.306(8), V = 1965.2(4) ?, Z = 2, Mr = 835.60, Dc = 1.412 g/cm3, F(000) = 854, T = 193 K, l(MoKa) = 0.7107 ?and m = 22.38 cm-1. The final R = 0.052 and wR = 0.076 for 8386 observed reflections with I ≥ 2s(I).

Synthesis and mesomorphic properties of Schiff base esters possessing terminal chloro substituent

A homologous series of Schiff base esters,4-chlorobenzylidene-4'-n-alkanoyloxyanilines,containing even number of carbons at the end groups of the molecules(C_(n-1)H_(2n-1)COO-,n=4,6,8,10,12,14,16) were synthesized.The mesomorphic properties were investigated by differential scanning calorimetry(DSC) and polarizing optical microscopy(POM).It was found that the end groups of the molecules had an effect on the mesomorphic properties.n-Butanoyloxy was found non-mesogenic,whilst n-hexanoyloxy exhibited monotropic smectic phase.The higher members in this homologous series were enantiotropic smectogens.

Synthesis and mesomorphic properties of new Schiff base esters with different alkyl chains

A new series of Schiff base esters, 4-（dimethylamino）benzylidene-4＇-alkanoyloxyanilines containing even number of carbons at the end group of the molecules （Cn-1H2n-1COO, n = 6, 8, 10, 12, 14, 16, 18） were synthesized. The present compounds were monotropic liquid crystals. It was also found that the end groups of the molecules had effect on the mesomorphic properties. C 2009 Sie Tiong Ha. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.

New mesogenic Schiff base esters comprising benzothiazole moiety:Synthesis and mesomorphic properties

A homologous series of Schiff base esters, 6-methoxy-2-（2-hydroxy-4-alkanoyloxybenzylidenamino）benzothiazoles, compris- ing a benzothiazole moiety as the core was synthesized. All the members of this series exhibited an enantiotropic nematic phase. The azomethine linkage along with the lateral hydroxyl and terminal methoxyl groups were found to exert an effect on the mesomorphic properties. 2009 Sie Tiong Ha. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.

Synthesis and mesomorphic properties of fluorinated Schiff's base liquid crystals containing vinyl end groups

Three kinds of fluorinated Schiff＇s base esters, 4-allyloxy-2-X-6-X-benzoic acid 4-[（2, 3, 4-trifluorophenylimino）methyl]phenyl ester, where X=H or F, were synthesized and characterized. Their chemical structures were identified by Fourier transform infrared spectroscopy （FTIR） and ^1H nuclear magnetic resonance （^1H NMR）. Their mesomorphic properties were studied by polarized optical microscopy （POM） and differential scanning calorimetry （DSC）. It was found that all the three compounds exhibited enantiotropic nematic phases only. And their cleating point temperature and thermal range of mesophase decreased with the number of fluorine atoms on the rigid core of the compounds; while their melting point temperature showed no distinct regularity.

Synthesis and mesomorphic behavior of benzothiazole-based liquid crystals having terminal methoxyl group

A homologous series of benzothiazole derivatives, 6-methoxy-2-（4-alkanoyloxybenzylidenamino）benzothiazoles, were synthesized and characterized using FT-IR, ^1H and ^13C NMR, mass spectrometry and elemental analysis. Enantiotropic nematic phase was observed throughout the entire series. Smectic C phase only emerged from the decanoyloxy derivative onwards. The terminal methoxyl group and the ester linkage influenced the mesomorphic behavior of the present series.

SYNTHESIS AND CHARACTERIZATION OF NOVEL CHIRAL SMECTIC C(Sc~*) PHASE SHISH-KEBAB TYPE LIQUID CRYSTALLINE BLOCK COPOLYMERS

A new series of chiral shish-kebab type liquid crystal block copolymers that form the smectic C(Sc*) phase was synthesized by solution polycondensation. The copolymers were characterized by GPC, DSC, TG, POM, X-ray diffraction and polarimeter. The copolymers 7 entered into liquid crystal phase whin they were heated to their melting temperatures (T-m) and the copolymers 8 were in liquid crystal phase at room temperature with low viscosities. The smectic sanded texture or focal-conic texture were observed on POM. All the chiral block copolymers showed high optical activity. No racemization has happened. Temperature-variable X-ray diffraction study together with POM and polarimetric analysis realized that they are chiral smectic C(Sc*) phase. Thus we offer in this report the first example of shish-kebab type liquid crystal block copolymers that form a chiral smectic C(Sc*) phase. The variation of melting and isotropization temperatures with molecular structure was also discussed.

SYNTHESIS OF DIAZA CROWN ETHER CHIRAL LIQUID CRYSTAL

A chiral liquid crystal crown ether containing diaza-18-crown-6 was synthesized with the help of CPK atomic model and in the meantime a nonchiral liquid crystal crown ether of alike structure was also synthesized for comparison, indicating that only the former was asymmetric. The present work represents the first attempt of the investigation in chiral liquid crystal crown ether, thus providing basis for further research into problems as such.

Synthesis and Crystal Structure of Complex of Zinc（Ⅱ） with Schiff Base—{Zn［CH3O（O）－C6H3CH3＝NN＝C（S）NH2］（DMF）}2

The title complex is a new binuclear Zn(Ⅱ) with chelate ligand of Schiff base containing S and N atom.The complex crystallizes in the orthorhombicspace group Pccn,with a=12.338(9),b=16.666(8),c=17.503(6),V=3599(6),Mr=723.52,Z=4,Dx=1.34 g/cm3,μ=15.22 cm-1,F(000)=1488.The structure was solved by direct methods and the final R=0.078.The crystal consists of discrete molecules with symmetric center at the center of the fourmembered ring consisting of two Zn atoms and two O atoms.

Syntheses, Crystal Structures and Antibacterial Activities of Two Heterocyclic Schiff Base Compounds

Two heterocyclic Schiff bases were synthesized via the condensation reactions of primary amines with carbonyl compounds. 2-[（4-pyridylmethylene）-amino] phenol （compound 1） was synthesized by the interaction of 4-pyridinecarboxaldehyde with o-aminophenol in ethanol solvent; N,N＇-bis（3-（furan-2-yl）allylidene）benzene-1,4-diamin （compound 2） was synthesized by the interaction of 3-（2-furyl）acrolein with p-phenylenediamine in ethanol medium. The compounds were characterized by elemental analysis, IR, MS and single-crystal X-ray diffraction. Compound 1 （C12H10N2O） crystallizes in the monoclinic system, space group P21/c with α = 7.0771（7）, b = 7.2820（7）, c = 19.849（2）, b = 96.3390（10）°, V = 1016.66（17） ？3, Z = 4, Mr = 198.22, Dc = 1.295 g/cm3, F（000） = 416, GOOF = 1.060, m = 0.085 mm-1, the final R = 0.0371 and wR = 0.0929 for 1497 observed reflections with I 〉 2σ（I）. Compound 2 （C20H16N2O2） crystallizes in the orthorhombic system, space group Fdd2 with α = 26.344（15）, b = 48.50（3）, c = 5.293（3）, V = 6764（7） ？3, Z = 16, Mr = 316.35, Dc = 1.243 g/cm3, F（000） = 2656, GOOF = 1.043, m = 0.081 mm-1, the final R = 0.0526 and wR = 0.1267 for 2059 observed reflections with I 〉 2σ（I）. 1 and 2 molecules are connected through hydrogen bonds to generate a 2D network and a 1D chain structure, respectively. The preliminary antibacterial activity results showed that the title compounds display excellent antibacterial activities to Escherichia coli, Staphylococcus aureus and Bacillus subtilis.

Synthesis of Schiff Base-type Liquid Crystalline Crown Ethers Containing Dibenzo-18-Crown-6 Unit

The synthesis and characterization of novel Schiff base liquid crystalline crown ethers prepared from the inter-mediates 4-(4-alkoxylbiphenyl-4-carbonyl)benzaldehyde, cis- and trans-4,4-diaminodibenzo-18-crown-6 are de-scribed. The structure of these compounds have been well characterized by elemental analysis, IR, 1H NMR and MS spectroscopy. The liquid-crystalline behavior of these compounds was also inverstigated by differential scanning calorimetry (DSC), polarizing optical microscopy (POM) with a heating stage and polarimetric analysis.

Syntheses,Crystal Structures and Property Studies on Cu(Ⅱ) and Co(Ⅱ) Complexes with 1,8-Naphthalimid Schiff Base

The ligand of N-（2-hydroxybenzylideneamino）-1,8-naphthalimide （HL） and its metal complexes of CuL2 （1） and CoL2 （2） have been synthesized. Elemental analysis, IR and X-ray single-crystal diffraction characterizations for 1 and 2 have been carried out. In the complexes of 1 and 2, the central metallic ions of Cu^2＋ and Co^2＋ coordinate with two deprotonated ligands of L-, respectively and adopt distorted square planar geometries. The thermal analysis result shows that the two complexes undergo two similar decomposition processes because of their similar geometric configurations. For the two complexes, fluorescence spectra measurements indicate that complex CoL2 emits stronger blue fluorescence than HL and the complex CuL2 does not emit fluorescence at all.

Syntheses, Crystal Structures and Fluorescent Properties of Two New Imidazolidino Schiff Base Compounds

Two new imidazolidino Schiff base compounds, （E）-N-（（quinoxalin-2-yl）methylene）- 2-（2-（quinoxalin-3-yl）imidazolidin-1-yl）ethanamine 1 and 2-（1-（2-（2-（quinoxalin-3-yl）imidazolidin- 1-yl）ethyl）imidazolidin-2-yl）quinoxaline 2, have been synthesized and characterized by elemental analysis, ^1H NMR, IR, MS and single-crystal X-ray diffraction. Crystallographic data for 1： C22H21N7, Mr = 383.46, monoclinic, space group P21, a = 7.0036（14）, b = 6.9151（14）, c = 19.701（4）A, β = 96.57（3）°, Z = 2, V = 947.9（3）A^3, Dc = 1.344 g/cm^3, F（000） = 404, μ = 0.085 mm^-1, Flack parameter = 0（2）, R = 0.0464 and wR = 0.1055; and those for 2： C24H26N8, Mr = 426.53, triclinic, space group PI, a = 9.6680（19）, b = 10.334（2）, c = 11.389（2）A, α= 104.12（3）, β = 102.95（3）, γ= 100.48（3）°, Z= 2, V = 1041.2（4）A3, Dc= 1.361 g/cm^3, F（000） = 452, μ = 0.086 mm^-1, R = 0.0373 and wR = 0.1155. For the two compounds, the five-membered imidazolidine rings all adopt envelope conformation. Moreover, the title compounds show one-dimensional layered and three-dimensional supramolecular chainlike structures, respectively. Fluorescent properties of the two compounds have been investigated in the solid state at room temperature. Compound 1 exhibits strong fluorescence and thus may serve as excellent candidates of green fluorescent materials.