共查询到20条相似文献,搜索用时 31 毫秒
1.
Two series of flavylium triflates carrying alkoxy side chains in the A-ring (benzo unit of chromylium salt) and thioethers in the B ring (phenyl unit) ( O n - Fla - S m ) as well as thioethers at both A and B ring ( S n - Fla - S m ) were synthesized in order to understand the effect of thioether functionalization on their self-assembly and electronic properties. Concentration-dependent and diffusion ordered (DOSY) NMR experiments of O 1 - iV - Fla - S 3 indicate the formation of columnar H-aggregates in solution with antiparallel intracolumnar stacking of the AC unit (chromylium) of the flavylium triflate, in agreement with the solid state structure of O 1 - V - Fla - S 1 . Thioether substitution on the B ring changes the linear optical properties in solution, whereas it has no effect on the A ring. According to differential scanning calorimetry, polarizing optical microscopy and X-ray diffraction bulk self-assembly of these ionic liquid crystals (ILCs) depends on the total number of side chains, yielding SmA and Lam Col phases for ILCs with 2–3 chains and Col ro, Col h phases for ILCs with 3–6 chains. Thus, we demonstrated that thioethers are a useful design tool for ILCs with tailored properties. 相似文献
2.
An alkylamide-substituted (−NHCOC 10H 21) hydrogen-bonded dibenzo[18]crown-6 derivative (1) was prepared to stabilise the ionic channel structure in a discotic hexagonal columnar (Col h) liquid crystal. The introduction of simple M +X − salts such as Na +PF 6− and K +I − into the ionic channel of 1 enhanced the ionic conductivity of the Col h phase of the M +·(1)·X − salts, with the highest ionic conductivity reaching ∼10 −6 S cm −1 for K +·(1)·I − and Na +·(1)·PF 6− at 460 K, which was approximately 5 orders of magnitude higher than that of 1. The introduction of non-ferroelectric 1 into the ferroelectric N, N′, N′′-tri(tetradecyl)-1,3,5-benzenetricarboxamide (3BC) elicited a ferroelectric response from the mixed Col h phase of (3BC) x(1) 1−x with x = 0.9 and 0.8. The further doping of M +X − into the ferroelectric Col h phase of (3BC) 0.9(1) 0.1 enhanced the ferroelectric polarisation assisted by ion displacement in the half-filled ionic channel for the vacant dibenzo[18]crown-6 of (3BC) 0.9[(M +) 0.5·(1)·(X −) 0.5] 0.1.An alkylamide-substituted (−NHCOC 10H 21) hydrogen-bonded dibenzo[18]crown-6 derivative (1) was prepared to stabilise the ionic channel structure in a discotic hexagonal columnar (Col h) liquid crystal. 相似文献
3.
Polystyrene copolymers of the type ( P −H) 1−x( P −(CH 2) n−COOSnR 3) x containing [(1‐oxoalkyl)oxy]triphenylstannane or tributyl[(1‐oxoalkyl)oxy]stannanes as side chains ( P −H=styrene; P −(CH 2) n−COOSnR 3 = para‐substituted styrene‐like monomeric unit with R=Ph ( x=0.1), Bu ( x=0.5); n=2–4) were investigated. The tributyl[(1‐oxoalkyl)oxy]stannane copolymer was prepared by direct conversion of the corresponding copolymeric methyl esters with hexabutyldistannoxane. By contrast, the [(1‐oxoalkyl)oxy]triphenylstannane copolymer could be prepared only by a procedure involving two reaction steps consisting of a preliminary hydrolysis of the related methyl ester ( P −H) 1‐x( P −(CH 2) n−COOMe) x followed by functionalization of the corresponding poly(carboxylic acid) ( P −H) 1‐x( P −(CH 2n−COOH) x with hydroxytriphenylstannane. Attempts to directly convert the methyl ester with hydroxytriphenylstannane or hexaphenyldistannoxane led to the formation of uncompletely functionalized product. The structure of the stannane‐functionalized polymers was investigated in solution and solid state by NMR, IR, and thermal analysis. The tributylstannane and triphenylstannane copolymers were assessed as chloride‐selective anion carriers in polymeric‐liquid‐membrane potentiometric ion‐selective electrodes. 相似文献
4.
Two dimethyldioctadecylammonium (DODA +) salts of a new keplerate with the general formula [Mo 132O 312S 60(SO 4) x(H 2O) 132–2x] (12 + 2x)? and abbreviated DODAn?Mo132S60 ( n = 44, 56) were synthesised and characterised. Both clusters were fully characterised by the combination of Polarised Optical Microscopy, Differential Scanning Calorimetry and Small-angle X-Ray Diffraction showing self-organisation in lamellar (L) liquid crystalline phases. We demonstrated that the lamellar periodicity h of the mesophases can be controlled with the number of DODA + associated to the clusters. Finally, these new results were compared to those gained from a previously published analogue, the fully oxo keplerate noted DODA 36?Mo 132 that also self-organise with temperature, but in a slightly more structured lamellar liquid crystalline phase. 相似文献
5.
Series of new Ni(II) metalomesogens of triangular molecular shape and forming Col h liquid crystalline (LC) phase were synthesised and described. Using in the molecular core the barbituric moieties that contain carbonyl or thiocarbonyl groups causes strong polarisation of the molecules and creates a permanent dipole moment μ, which was confirmed by quantum mechanical calculations. The relationship between molecular dipole moment and self-organisation of molecules into the columnar phase was considered. The position of alkyl and alkoxy chains substituted at phenyl ring that affects LC phase formation seems to be connected with planar conformation of the attached chains. These can broaden the mesogenic core and stabilise the Col h mesophase. 相似文献
6.
盘状液晶分子能自组装成高度有序的六方柱状介晶相. 其各向异性的载流子高速迁移率使其成为较理想的有机光电子材料. 采用分子间氢键锚定柱状相, 获得介晶相温度范围宽、有序度高的苯并菲盘状液晶是本研究的目的. 本文通过分子设计, 合成了3个系列, 共18个有两种不同软链的苯并菲盘状液晶化合物C 18H 6(OR) 5(OCH 2COOEt), C 18H 6(OR) 5(OCH 2COOBu)和C 18H 6(OR) 5(OCH 2CONHBu), 其中R=C nH 2n+1, n=4~9. 化合物的纯度和结构通过 1H NMR和元素分析确证. 化合物热稳定性通过热重分析(TGA)测定, 并显示出较高的热稳定性. 通过偏光显微镜(POM)和差示扫描量热法(DSC)对这些化合物的热致液晶性进行了研究. 结果显示对于分子中含有酰胺基的苯并菲液晶化合物C 18H 6(OR) 5(OCH 2CONHBu), 与具有同样软链长度的分子中不含酰胺键的化合物系列C 18H 6(OR) 5(OCH 2COOBu)相比较, 前者由于柱内分子间氢键的形成, 具有更高的熔点和清亮点. 相似文献
7.
The change in the valence state of nanocluster can induce remarkable changes in the properties and structure. However, achieving the valence state changes in nanoclusters is still a challenge. In this work, we use Cu 2+ as dopant to “oxidize” [Ag 62S 12(SBu t) 32] 2+ (4 free electrons) to obtain the new nanocluster: [Ag 62−xCu xS 12(SBu t) 32] 4+ with 2 free electrons. As revealed by its structure, the [Ag 62−xCu xS 12(SBu t) 32] 4+ (x=10∼21) has a similar structure to that of [Ag 62S 12(SBu t) 32] 2+ precursor and all the Cu atoms occupy the surface site of nanocluster. It′s worth noting that with the Cu atoms doping, the [Ag 62−xCu xS 12(SBu t) 32] 4+ nanocluster is more stable than [Ag 62S 12(SBu t) 32] 2+ at higher temperature and in electrochemical cycle. This result has laid a foundation for the subsequent application and exploration. Overall, this work reveals crystals structure of a new Ag−Cu nanocluster and offers a new insight into the electron reduction/oxidation of nanocluster. 相似文献
8.
A homologous series of disc-like 1,3,6-trisubstituted benzo[ e][1,2,4]triazin-4-yls 1[n] was synthesized and their structural, thermal, optical, magnetic, and electric properties were investigated. The results demonstrate that all members of the series display a Colh phase with clearing temperatures depending on the length of the alkoxy chains at the N(1) position, hence the shape of the disc. Powder XRD and magnetic data indicate a gradual change in the column diameter and magnetic behavior in the series in transition from half-disc in 1[0] (antiferromagnetic interactions) to full-disc geometry in the 1[12] homologue (ferromagnetic interactions with J/ kB=+7.5 K). Studies of binary systems revealed that a 1 : 1 mixture of 1[0] and 1[12] exhibits modest stabilization of the Colh phase with an expanded range, and magnetic behavior typical for 1[0] in the rigid phase obtained from the melt. Electric measurements demonstrated hole mobility of ∼10 −3 cm 2 V −1 s −1 and dark conductivity of ∼10 −11 Scm −1 in the mixture and individual compounds. The latter is enhanced up to 4 times by simultaneous illumination with UV light. 相似文献
9.
Novel liquid crystal materials based on 1,3,5-benzenetrisamide derivatives with three pendant 2-phenyl-5-(mono-, di-, and/or tri- n-alkoxyphenyl)-1,3,4-oxadiazole arms ( Ia–c, IIa–c) were prepared. The mesomorphic properties of these compounds were characterised and studied by differential scanning calorimetry, polarising optical microscopy and X-ray diffraction. The formation of a columnar mesophase was found to be dependent on the number of alkoxy side chains. The compounds Ib and IIb, with a total of six alkoxy chains, and compounds Ic and IIc, with nine alkoxy chains, exhibited an enantiotropic hexagonal columnar ( Colh ) phase with high isotropisation temperatures; however, compounds Ia and IIa with a total of three alkoxy chains formed a crystalline phase. Compounds IIb and c were room temperature liquid crystals. 相似文献
10.
Two polycatenar materials composed of a four‐aromatic‐ring core with a perfluorinated moiety attached in one terminal position through either butylene‐ or pentylene spacer groups, and three tetradecyloxy chains at the other end (abbreviated as 14PC 4F and 14PC 5F), were investigated to study the effect of pressure on the phase transition behaviour. A polarizing optical microscope equipped with a high pressure optical hot stage, was used for the purpose. The T vs. P phase diagrams of 14PC 4F and 14PC 5F were constructed in the pressure region up to 100 MPa. 14PC 4F showed the stable crystal (Cr 1)–columnar tetragonal (Col tet)–smectic A (SmA)–columnar hexagonal (Col h)–isoropic liquid (I) phase transition sequence under all pressures. 14PC 5F exhibited the phase sequence metastable crystal (Cr 2)–cubic (Cub)–Col tet–SmA–I in a melt‐cooled sample on heating under pressure. But when the melt‐cooled Cr 2 sample was annealed at 52–54°C for 2–3 h, the stable crystal (Cr 1) was formed slowly, giving a stable Cr 1–Cub–Col tet–SmA–I phase sequence. The temperature region of the stable cubic phase broadened with increasing pressure. Furthermore a new mesophase of 14PC 5F was pressure‐induced between the I and SmA phases on cooling at pressures above about 16 MPa. Since the monotropic mesophase exhibited a texture very similar to that of the high temperature Col h phase of 14PC 4F with planar orientation, the new phase was assigned at a high temperature columnar hexagonal phase of 14PC 5F. 相似文献
11.
We report on our serendipitous finding of the anomalous behavior of a novel liquid crystalline (LC) molecule U H/H , containing a U‐shaped handle. While U H/H itself shows a bicontinuous cubic (Cub bi) phase, U H/H in the presence of pyrene molecules as an external guest forms a hexagonal columnar (Col h) phase without phase separation. Interestingly, even when the pyrene molecules were covalently attached to U H/H ( U Py/Py ), the molecule exhibited a Col h phase, with a similar columnar geometry to that of U H/H mixed with pyrene molecules (1–4 equiv.). This result means that no matter how the pyrene moieties are incorporated in the LC system, the resultant material exhibited a similar molecular assembly with a columnar geometry. This finding is interesting because U H/H and pyrene molecules do not seem to have specific interactions or shape complementarity to form a columnar assembly, as in the case of U Py/Py . © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019 , 57, 342–351 相似文献
12.
Small change in chemical structure of discotic liquid crystals can cause big difference in their mesomorphism. Replacing of the alkoxy peripheral chains of triphenylene by oxygen-atom containing ester chains would result in novel mesomorphism. A series of mixed tail triphenylenes containing propoxyacetyloxy and alkoxy, abbreviated as C18H6(OCnH2n+1)3(OCOCH2OC3H7)3, n=4-8, and hexa(propyloxyacetyloxy)triphenylene, C18H6(OCOCH2OC3H7)6 were synthesized. Thermal gravimetry analysis (TGA) of three discogens showed that they had good thermal stability till 350 ℃. The mesomorphism was investigated through differential scanning calorimetry (DSC) and polarized optical microscopy (POM). The preliminary X-ray diffraction (XRD) results of one compound showed that it exhibited ordered hexagonal columnar (Colho) mesophase. These mixed tail triphenylene derivatives possessed much stable Colho mesophase and wider mesophase ranges than their hexaalkoxytriphenylene C18H6(OR)6 and hexaalkanoyloxytriphenylene C18H6(OCOR')6 analogues. The asymmetrical compounds 2,6,11-trialkoxy-3,7,10-tri(2-propyloxyacetyloxy)triphenylenes with n=5-8 displayed higher clearing points and wider temperature ranges than their symmetrical isomers 2,6,10-trialkoxy-3,7,11-tri(2-propyloxyacetyloxy)- triphenylenes, while C18H6(OCOCH2OC3H7)6 had the highest clearing point due to the β-oxygen-atom effect. 相似文献
13.
Novel liquid crystal materials based on 3,4-di- n-alkoxybenzoylthiosemicarbazides ( 3a– h, n = 5–10, 12, 14) were synthesised. The mesomorphic properties of these compounds were characterised and studied by differential scanning calorimetry, polarising optical microscopy and X-ray diffraction. Compound 3a did not show mesomorphic properties; 3b shows a monotropic hexagonal columnar (Col h) phase. Compounds 3c– h display an enantiotropic Col h phase. The mesomorphic properties were found to be dependent on the length of alkoxy side chains. In N, N-dimethylformamide solution, all the compounds displayed a room temperature emission with λ max at 361–332 nm. A thermogravimetric analysis also was performed. 相似文献
14.
The crystal structures of [1,3‐bis(diphenylphosphino)ethane‐κ 2P, P′](pyridine‐2‐sulfinato‐κ 2N, S)(pyridine‐2‐thiolato‐κ 2N, S)ruthenium(II), [Ru(C 5H 4NO 2S) 0.33(C 5H 4NS) 1.67(C 26H 24P 2)] or [Ru(pySO 2) 1−x(pyS) 1+x(dppe)] ( x = 0.67), (I), and [1,3‐bis(diphenylphosphino)propane‐κ 2P, P′](pyridine‐2‐sulfinato‐κ 2N, S)(pyridine‐2‐thiolato‐κ 2N, S)ruthenium(II), [Ru(C 5H 4NO 2S) 0.355(C 5H 4NS) 1.645(C 27H 26P 2)] or [Ru(pySO 2) 1−x(pyS) 1+x(dppp)] ( x = 0.645), (II), are composed of neutral distorted octahedral Ru II complexes with chelating pyridine‐2‐thiolate, pyridine‐2‐sulfinate and biphosphine ligands. The S atoms are trans to each other, while pairs of P and N atoms are in cis positions. Partial double‐bond character is observed for C—S. The crystal packing consists of monolayers stabilized by C—H⋯O and C—H⋯S interactions, and is affected by the alkyl‐chain lengths. 相似文献
15.
UO 2F 2 abstracts F − anions from TlF in liquid ammonia solution and the compound [Tl 2(NH 3) 6][{UO 2F 2(NH 3)} 2(μ-F) 2] is formed. The compound has been characterized by single crystal X-ray diffraction, Raman spectroscopy and quantum-chemical calculations for the solid state. Quantum-chemical investigation of the [{UO 2F 2(NH 3)} 2(μ-F) 2] 2− anion showed that the U−(μ-F)−U σ-3c-4e-bond is essentially ionic. The [Tl 2(NH 3) 6] 2+ cation shows a thallophilic Tl⋅⋅⋅Tl interaction. Fluoride ion affinities (FIAs) were calculated for different UO 22+ species [UO 2F x] 2−x and [UO 2F x(NH 3) 5−x] 2−x with x=0 to 4. 相似文献
16.
The reaction of Fe(NO 3) 3⋅9 H 2O with KOH under hydroflux conditions at about 200 °C produces red crystals of K 2−xFe 4O 7−x(OH) x in a quantitative yield. In the crystal structure, edge-sharing [FeO 6] octahedra form Fe 2O 6] honeycomb nets. Pillars consisting of pairs of vertex-sharing [FeO 4] tetrahedra link the honeycomb layers and form columnar halls in which the potassium ions are located. The trigonal ( P 1 m) and the hexagonal ( P6 3/ mcm) polytypes of K 2−xFe 4O 7−x(OH) x show oriented intergrowth. The sub-stoichiometric potassium content ( x≈0.3) is compensated by hydroxide ions. K 2−xFe 4O 7−x(OH) x is an antiferromagnet above 2 K and its magnetic structure was determined by neutron powder diffraction. Under ambient conditions, K 2−xFe 4O 7−x(OH) x hydrolyzes and K 2CO 3 ⋅ H 2O forms gradually on the surface of the K 2−xFe 4O 7−x(OH) x crystals. Upon annealing at air at about 500 °C, the potassium atoms in the columnar halls start to order into a superstructure. The thermal decomposition of K 2−xFe 4O 7−x(OH) x proceeds via a topotactic transformation into K 1+x′Fe 11O 17, adopting the rhombohedral β’’ or the hexagonal β-aluminate-type structure, before γ-Fe 2O 3 is formed above 950 °C, which then converts into thermodynamically stable α-Fe 2O 3. 相似文献
17.
Chebyshev polynomials Ψ
q
(x) orthogonal on a finite arbitrary system of points x
i
(i = 1−N) are used to interpolate changes in nematic-isotropic liquid phase transition temperatures t
c(x) in homologous series of liquid crystals (x = 1/n, where n is the number of the homologue). The expansion of the t
c(x) function into a series in Ψ
q
(x) polynomials was found to be very effective. Already at q ≤ 3, this series describes the known types of the t
c(x) dependences with high accuracy and very small root-mean-square deviations for mesogenic molecules of various chemical structures and dimensions. The dependence of the limiting t
l
= t
c(0) value on the form of X-shaped molecules and linear dimensions of N-mers with N rigid aromatic fragments linked with each other by flexible spacer chains was studied. 相似文献
18.
New liquid crystals having a non‐conventional structure have been synthesised from a six‐armed cyclotriphosphazene core, [N 3P 3(OC 6H 4OH‐4) 6], which was condensed with polycatenar acids. Reactions were monitored by 31P{ 1H} and 1H NMR spectroscopy and the chemical structure of the resulting materials was confirmed by different spectroscopic techniques and mass spectrometry (MALDI‐TOF). Results were in accordance with monodisperse, fully functionalised cyclotriphosphazenes. Thermal and mesomorphic properties were studied by optical microscopy, differential scanning calorimetry and X‐ray diffraction. All of the synthesised phosphazenes, substituted with benzyl ether chains, show a high thermal stability and exhibit mesomorphic properties, which depend on the number and type of alkyl terminal chains located at the periphery of the mesogens. Mesomorphic properties range from Col h for cph‐A1 and cph‐A2 to a cubic phase detected for cph‐A3 , which has the larger number of alkyl chains. Furthermore, helical order was detected on X‐ray data of cph‐A2 , which has chiral branched chains. Circular dichroism spectra of annealed films at mesophase temperature show a signal attributed to the chiral helical arrangement of the mesogenic chromophores. 相似文献
19.
A simple and versatile method for general synthesis of uniform one‐dimensional (1D) M xCo 3−xS 4 (M=Ni, Mn, Zn) hollow tubular structures (HTSs), using soft polymeric nanofibers as a template, is described. Fibrous core–shell polymer@M‐Co acetate hydroxide precursors with a controllable molar ratio of M/Co are first prepared, followed by a sulfidation process to obtain core–shell polymer@M xCo 3−xS 4 composite nanofibers. The as‐made M xCo 3−xS 4 HTSs have a high surface area and exhibit exceptional electrochemical performance as electrode materials for hybrid supercapacitors. For example, the MnCo 2S 4 HTS electrode can deliver specific capacitance of 1094 F g −1 at 10 A g −1, and the cycling stability is remarkable, with only about 6 % loss over 20 000 cycles. 相似文献
20.
Ionic liquid crystals (ILCs) are a class of materials that present a large and varied form of applicability and whose properties can change dramatically with small modifications in their molecular structure. It is, therefore, of great importance to improve the knowledge about the property–molecular structure relationship. In this study, we present the synthesis and characterisation of 7 new rod- and wedge-shaped ILCs, whose liquid crystalline behaviour variation is related to the variations in the number of alkoxy chains and/or in the spacer chain length. All compounds have a rigid core constituted by a tolane group and a 1,2,3-triazole heterocycle, which is connected to a pendant 1-methylimidazolium through a alkyl spacer chain. The mesomorphic properties were studied by DSC, thermogravimetric analysis, polarising optical microscopy, wide angle X-ray diffraction and SAXS with synchrotron radiation. The increase in the number of long alkoxy chains changed the molecular self-assembly from bilayered SmA 2 and SmC 2 to hexagonal columnar, passing through oblique columnar, bicontinuous cubic and hexagonal close-packed mesophase. On the other hand, the increase in the alkyl spacer chain length has an especially significant effect for the compounds with two terminal alkoxy chains, where a Col o/Col h – Cub v – HCP phase sequences were observed. 相似文献
|