Synthesis and properties of organic–inorganic hybrid liquid crystal gels

Organic–inorganic hybrid liquid crystal (LC) gels have been synthesised by the thiol-ene reaction of a multifunctional cyclic siloxane, 1,3,5,7-tetravinyl-1,3,5,7-tetramethylcyclotetrasiloxane (TVMCTS) and alkane dithiols, 1,6-hexanedithiol (HDT) or 1,9-decanedithiol (DDT), in LC matrices, 4-cyano-4?-pentylbiphenyl (5CB) or 4′-n-octyl-4-cyano-biphenyl (8CB). The LC gels were prepared in an isotropic phase at 70°C or mesophases at 25°C using radical initiators. The phase transition temperatures from a mesophase to an isotropic phase of the resulting gels were lower than those of the original LCs. The gels containing 8CB (8CB gels) prepared at 25°C showed two phase transitions: smectic-to-nematic and nematic-to-isotropic transitions. By contrast, the 8CB gels synthesised in the isotropic phase showed only one phase transition from smectic phase directly to isotropic phase. Reaction conversions in the LC gels prepared at 70°C were higher than that in the gels prepared at 25°C. Scanning microscopic light scattering analysis of the LC gels cleared homogeneous small size mesh with a small amount of large defect. Polarisation micrographs of the LC gels showed framed optical textures derived from the LC molecules at room temperature. The LC gels containing more than 90 wt% of LC showed electro-optic response.     

Synthesis,crystal structure and properties of two terbium complexes with 2,2′-bipyridine

Two new complexes {[Tb(2-IBA)₃ · 2,2′-bipy]₂ · C₂H₅OH} (1) and [Tb(2-ClBA)₃ · 2,2′-bipy]₂ (2) (2-IBA = 2-iodobenzoate; 2-ClBA = 2-chlorobenzoate; 2,2′-bipy = 2,2′-bipyridine) were prepared and their crystal structures determined by X-ray diffraction. Complex 1 is composed of two types of binuclear molecules, [Tb(2-IBA)₃ · 2,2′-bipy]₂ (a) and [Tb(2-IBA)₃ · 2,2′-bipy]₂ (b), and an uncoordinated ethanol molecule. In molecule (a), two Tb³⁺ ions are linked by four 2-IBA groups, all bidentate-bridging. In molecule (b), two Tb³⁺ ions are held together by four 2-IBA groups in two coordination modes, bidentate-bridging and chelating-bridging. In the two molecules, each Tb³⁺ ion is further bonded to one chelating 2-IBA group and one chelating 2,2′-bipy molecule, resulting in coordination numbers of eight for (a) and nine for (b). The structural characteristics of 2 are similar to that of molecule (b) in 1. The two complexes, 1 and 2, both emit strong green fluorescence under ultraviolet light with the ⁵D₄ → ⁷F _j (j = 6–3) emission of Tb³⁺ ion observed.     

Synthesis and mesomorphic properties of trifluorobenzoate liquid crystal

Four series of trifluorobenzoate liquid crystals have been synthesized. Their phase transition temperatures have been also measured by texture observation in a polarizing microscope and confirmed by DSC. The influence of the lateral fluoro-substitution and triple bond has been also discussed.     

Synthesis and photophysical properties of europium pentafluorinated β-diketonate complexes

Research on Chemical Intermediates - Two pentafluorinated β-diketone ligands, 4,4,5,5,5-pentafluoro-1-(4-methoxyphenyl)pentane-1,3-dione (PFMP) and 4,4,5,5,5-pentafluoro-1-(4-dimethyl...     

Synthesis and luminescence-spectral properties of benzoheterocyclic β-diketones and their complexes with europium

In order to solve some environmental and biomedical problems, we synthesized fluorinated heterocyclic β-diketones and estimated the luminescence-spectral properties of these compounds complexes with the ions of rare-earth elements as the possible reagents for immunofluorescence analysis.     

Synthesis and liquid crystal properties of some 2,6‐disubstituted anthracenes

The synthesis and liquid crystalline properties of some new 2,6‐disubstituted anthracenes are described. Symmetrical alkylphenyl derivatives exhibit smectic mesophases, whereas simpler structures are non‐mesogenic. One unsymmetrically substituted anthracene exhibits a narrow nematic phase. The potential for these molecules to act as phototriggers has been investigated but efficient photodimerisation cannot be achieved.     

Synthesis,characterization and luminescence properties of a coordination polymer based on self-assembly of PrIII with inorganic–organic hybrid bridging ligands

A new coordination polymer having the formula [Pr(μ ₅-S₂O₃)(μ ₄-tp)_0.5(H₂O)] _n (1) (S₂O₃ = thiosulfate dianion; tp = terephthalate dianions) was obtained by in situ reaction of Pr₂(SO₄)₃ · 6H₂O with H₂tp ligands under solvothermal conditions (H₂O/ethanol). The coordination polymer obtained was characterized by elemental analysis, FT-IR, thermogravimetry (TG), fluorescent spectra and single crystal X-ray diffraction analysis. The most intriguing structural feature is that the complex exhibits a 3D open framework resulting from bridge-linking coordination between ligands and praseodymium ions. Additionally, 1 has characteristic emission spectra of Pr^III with good fluorescence properties. This is the first coordination polymer based on thiosulfate/terephthalate ligands and a rare earth metal and has an unprecedented pentadentate-bridge-linking coordination mode of the thiosulfate group.     

Synthesis,properties and crystal structures of volatile dimethylgold(III) complexes based on phenyl-containing β-diketones and β-iminoketone

We have synthesized and studied volatile dimethylgold(III) complexes based on phenyl-containing β-diketones and β-iminoketone, namely (CH₃)₂Au(C₆H₅–CO–CH–CO–CH₃), (CH₃)₂Au(bac) (1); (CH₃)₂Au(C₆H₅–CO–CH–CO–CF₃), (CH₃)₂Au(btfa) (2); and (CH₃)₂Au(C₆H₅–CO–CH–C(NH)–CH₃), (CH₃)₂Au(i-bac) (3). The obtained compounds were identified by elemental analysis, ¹H NMR and IR-spectroscopy, and were characterized by DTA and single-crystal X-ray diffraction studies. In compounds 2 and 3, the Au atom has a square coordination environment AuC₂O₂ and AuC₂NO, respectively.     

Three inorganic–organic hybrid compounds based on Keggin polyoxometalate and transition metal complexes: crystal structures and electrochemical properties

Polyoxometalate (POM)-based coordination polymers, [Cu(L)₂][SiW₁₂O₄₀]·4py·H₂O (1), [Ag(py)₂]₄[SiW₁₂O₄₀] (2) and [Co(L)₃]₂[SiW₁₂O₄₀]·py·7H₂O (3) (L?=?pyridine-2-carboxylic acid, py?=?pyridine), have been obtained hydrothermally and characterized by elemental analyses, IR and single-crystal X-ray diffraction analyses. Electrochemical properties are also investigated.     

Synthesis and characterization of yttrium,europium, terbium and dysprosium complexes containing a novel type of triazolyl–oxazoline ligand

We report the synthesis of a novel type of bidentate chiral ligand which structurally derives from the association of a 1,2,3-triazole ring with a chiral oxazoline. Yttrium and lanthanide nitrato-complexes of the new triazolyl–oxazoline ligand were prepared and characterized. The coordination mode of the ligand was ascertained by means of DFT calculations. Trivalent europium and terbium derivatives resulted appreciably photoluminescent upon excitation with UV light, showing the typical ⁵D₀ → ⁷F_J and ⁵D₄ → ⁷F_J emissions, respectively. These species were successfully used for the preparation of luminescent-doped polymeric materials.     

Synthesis and liquid crystalline properties of a series of cholesterol‐based dimesogenic compounds

The synthesis and mesomorphic properties of a series of novel dimesogenic compounds containing the cholesteryl ester unit and a phenyl benzoate group are reported. The two mesogenic units of these compounds are linked through dicarboxylic ester bonds, with alkylene spacer lengths of 2, 4, 6 and 8 methylene units. The chemical structures and liquid crystalline properties of this series of compounds were characterized by FTIR, ¹H NMR, hot stage‐coupled polarizing microscopy and DSC. The results show that this series of compounds are cholesteric liquid crystals over a wide range, both during heating and cooling, and they exhibit iridescent colours in the liquid crystalline state.     

Synthesis,crystal structures,and photoluminescence of two new zinc complexes based on 2,2′-thiodibenzoic acid

{[Zn₂(tdba)₂(phen)₂(H₂O)₂]?·?2H₂O?·?2DMF} _n (1) and [Zn(tdba)(bpy)] _n (2) (H₂tdba?=?2,2′-thiodibenzoic acid, phen?=?1,10-phenanthroline, bpy?=?2,2′-bipyridine, DMF?=?dimethylformamide) were hydrothermally synthesized, and characterized by single-crystal X-ray diffraction analysis, FT-IR, and elemental analysis. The obtained complexes exhibit different structures. Compound 1 is 0-D with tdba connecting two Zn ions in a μ ₁–η ¹/μ ₁–η ¹ coordination forming a dinuclear molecule. Each molecule is further connected with neighbors via hydrogen-bonding and π?···?π interactions. Compound 2 displays a 1-D structure in which Zn²⁺ centers are connected via tdba anions into 1-D chains propagating along the a-axis; these chains are further packed via π?···?π interactions. In addition, photoluminescence for 1 and 2 has been investigated.     

Synthesis and luminescence properties of Eu(III)-doped silica nanorods based on the sol–gel process

Uniform Eu³⁺-doped SiO₂ nanorods were synthesized through a simple sol–gel method using cetyltrimethylammonium bromide (CTAB) as surfactant template and tetraethylorthosilicate as silicon source. X-ray diffraction, energy-dispersive X-ray spectroscopy, Fourier transform infrared spectrum, scanning electron microscope (SEM), transmission electron microscopy, and photoluminescence spectra were employed to characterize the products in detail. The nanorods have good uniformity and their diameters and lengths are in the range of 200–300 and 500–700 nm through the SEM images, respectively. The formation of the nanorods was studied by taking SEM images after different aging time. The experimental results indicate that CTAB plays a crucial role in the formation of the silica nanorods. The luminescence of Eu³⁺-doped SiO₂ nanorods is dominated by red-emission around 612 nm due to intra-atomic 4f → 4f (⁵D₀ → ⁷F₂₎ transition of Eu³⁺ ions. Furthermore, the effect of doping concentrations of Eu³⁺ ions on the luminescence was investigated.     

Synthesis,crystal structures,luminescence and thermal properties of lanthanide complexes containing 2,5-dichlorobenzoic acid and 2,2:6′,2″-terpyridine

Journal of Thermal Analysis and Calorimetry - Three novel ternary lanthanide complexes [Ln(2,5-DClBA)3(terpy)(H2O)] (Ln = Eu (1), Tb (2), Ho (3),...     

Synthesis and antiadrenergic properties of β-substituted alcohols based on 6-hydroxymethylpyridoxine

An approach to the synthesis of epoxides based on 6-hydroxymethylpyridoxine acetals was developed. The epoxides obtained were involved in the ring opening reactions by nitrogen-, oxygen-, and sulfur-containing nucleophiles. Cytotoxicity and antiadrenergic properties of some synthesized compounds were studied on the models in situ and in vivo.     

Syntheses,crystal structures and photochemistry of two new organic–inorganic hybrid compounds based on copper–glycin complexes and paradodecatungstates

Two organic–inorganic hybrid materials built from copper–glycin complexes and paradodecatungstates, Na₆[{Cu(gly)(H₂O)}]₂[{Cu(H₂O)}(H₂W₁₂O₄₂)] ? 21H₂O (1) and Na{Na(H₂O)₆}{Na(H₂O)₄}₃[{Cu(gly)₂}]₂{H₅(H₂W₁₂O₄₂)} ? 8.5H₂O (gly = glycin) (2), have been synthesized in aqueous solution and characterized by IR, UV, TG, elemental analysis, electrochemistry, and single-crystal X-ray analyses. In 1, [H₂W₁₂O₄₂]^10? building block connects two neighboring clusters with [Cu(H₂O)]²⁺ groups to produce an infinite 1-D chain; then these chains are linked through [Cu(gly)(H₂O)]⁺ groups to form a 2-D layer structure, which is further joined by Na⁺ to form a 3-D network. In 2, [H₂W₁₂O₄₂]^10? decorated by two [Cu(gly)₂] moieties connects four adjacent clusters with six Na⁺ into a 2-D layer. In addition, luminescence and photocatalysis properties of these compounds have been investigated.     

Synthesis and mesomorphic properties of new azine-type liquid crystals

A series of symmetrical azine-type liquid crystals were synthesized. The characteristic of these liquid crystals is that they had high clearing point ( ～320 ℃) and broad thermal range of nematic phase ( ～154 ℃). It was also found that the end groups of the liquid crystals had effect on the mesomorphic properties.     

Synthesis and crystal structures of dichlorocyclopentadienyl β-diketonate titanium complexes

Complexes of acetylacetonatodichlorocyclopentadienyltitanium(IV) (1) and dichlorocyclopentadienyl(2,2,6,6-tetramethyl-3,5-heptanedionato)titanium(IV) (2) have been prepared and their crystal structures determined by X-ray diffraction methods. Complex 1 crystallizes in space group P2₁/m with a?=?7.1893(10), b?=?11.7680(17), c?=?7.6129(11) Å, β?=?109.901(12)°; complex 2 crystallizes in space group P2₁/n with a?=?10.065(2), b?=?16.322(3), c?=?12.219(2) Å, β?=?110.99(3)°. The molecular structures of 1 and 2 can be described as square-based pyramidal, with the centroid of the C₅H₅ ring occupying the apical site and the bidentate β-diketonate and two chloride ligands occupying the basal positions. The average distances between titanium and oxygen atoms are 1.991(2) and 1.967(3) Å in compounds 1 and 2, respectively.     

Hydrothermal synthesis, crystal structure, and properties of two novel binuclear complexes based on Zaltoprofen and 2,2′-bipyridine ligands

Two novel binuclear metal-organic coordination complexes [M₂(Zaltoprofen)₂(Bipy)₂] [M = Cd (I), Zn (II); Zaltoprofen = 5-(1-carboxyethyl)-2-(phenylthio)phenylacetic acid, Bipy = 2,2′-bipyridine) have been synthesized under hydrothermal conditions and characterized by single crystal X-ray diffraction, elemental analysis, IR and electronic spectroscopy, powder X-ray diffraction, and fluorescent properties. Complexes I, II crystallize isomorphously in the monoclinic space group P2₁/c. Structural analysis shows that the M(II) atom of I and II is coordinated with four oxygen atoms from the carboxyl group of the Zaltoprofen together with two nitrogen atoms from the Bipy. The 3D structures of the complexes are stabilized by π-π stacking interactions.     

Synthesis and structure of new europium(ɪɪɪ) and terbium(ɪɪɪ) coordination polymers with trans-1,4-cyclohexanedicarboxylic acid

Russian Chemical Bulletin - Two new metal-organic frameworks of composition [Eu2(phen)2Cl2(chdc)2] ? 1.1DMF? ?0.7diox (1?1.1DMF?0.7diox, phen is 1,10-phenanthroline,...