端基含4个丁氧基苯介晶基元光致变色液晶树状物的合成、结构及液晶性研究

合成了周边含4个丁氧基偶氮苯介晶基元(M5)端基新的零代光致变色液晶树状物(D0),并用元素分析、核磁共振、基质辅助激光解吸飞行时间质谱、红外、紫外、偏光显微镜、差示扫描量热(DSC)和广角X射线衍射法(WAXD)表征.D0显示向列相,与M5相同,树状物相态由介晶基元相态所决定,D0的相行为:K138N147I145N118K.对零代(D0)、一代(D1)、二代(D2)和三代(D3)液晶树状物的清亮焓、清亮熵、熔化焓和熔化熵进行了比较.     

Structural evolution in the isotropic channel of a water-nonionic surfactant system that has a disconnected lamellar phase: a 1H NMR self-diffusion study

We showed in a previous study that a water-nonionic surfactant system, where the surfactant is a 9:1 mixture of tetraethylene glycol monodecyl ether (C(10)E(4)) and pentaethylene glycol monodecyl ether (C(10)E(5)), forms a disconnected lamellar (L(α)) phase. Thus, the isotropic phase spans the whole concentration range from the water-rich L(1) region to the surfactant-rich L(2) region of the phase diagram. The L(1) and L(2) regions are connected via an isotropic channel that separates the two regions of the L(α) phase. In this letter, we monitored the structural evolution of the isotropic phase along a path through this isotropic channel via (1)H NMR self-diffusion measurements. We used this technique because it enables us to distinguish between discrete and bicontinuous structures by comparing the relative self-diffusion coefficients (obstruction factors) D/D(0) of the solvents (i.e. of water and surfactant in the present case). We found that the obstruction factor of water decreases whereas the obstruction factor of the surfactant increases with increasing surfactant concentration and increasing temperature. This trend is interpreted as the transition from a water-continuous L(1) region, which contains discrete micelles, to a bicontinuous structure, which may extend to very high surfactant concentrations. Although there is good evidence of bicontinuity over a broad concentration range, there is no evidence of inverse micelles or any other microstructure at the highest concentration studied in the surfactant-rich L(2) phase.     

Molecular insight into the electrostatic membrane surface potential by 14n/31p MAS NMR spectroscopy: nociceptin-lipid association

Exploiting naturally abundant (14)N and (31)P nuclei by high-resolution MAS NMR (magic angle spinning nuclear magnetic resonance) provides a molecular view of the electrostatic potential present at the surface of biological model membranes, the electrostatic charge distribution across the membrane interface, and changes that occur upon peptide association. The spectral resolution in (31)P and (14)N MAS NMR spectra is sufficient to probe directly the negatively charged phosphate and positively charged choline segment of the electrostatic P(-)-O-CH(2)-CH(2)-N(+)(CH(3))(3) headgroup dipole of zwitterionic DMPC (dimyristoylphosphatidylcholine) in mixed-lipid systems. The isotropic shifts report on the size of the potential existing at the phosphate and ammonium group within the lipid headgroup while the chemical shielding anisotropy ((31)P) and anisotropic quadrupolar interaction ((14)N) characterize changes in headgroup orientation in response to surface potential. The (31)P/(14)N isotropic chemical shifts for DMPC show opposing systematic changes in response to changing membrane potential, reflecting the size of the electrostatic potential at opposing ends of the P(-)-N(+) dipole. The orientational response of the DMPC lipid headgroup to electrostatic surface variations is visible in the anisotropic features of (14)N and (31)P NMR spectra. These features are analyzed in terms of a modified "molecular voltmeter" model, with changes in dynamic averaging reflecting the tilt of the C(beta)-N(+)(CH)(3) choline and PO(4)(-) segment. These properties have been exploited to characterize the changes in surface potential upon the binding of nociceptin to negatively charged membranes, a process assumed to proceed its agonistic binding to its opoid G-protein coupled receptor.     

NMR investigation of the dynamics of banana shaped molecules in the isotropic phase: a comparison with calamitic mesogens behaviour

The first translational self-diffusion NMR measurements in the isotropic phase of banana-shaped liquid crystals are reported. In this paper, two banana-shaped mesogens, having a similar molecular structure and showing a nematic phase, have been investigated by means of translational self-diffusion NMR, (2)H NMR spin-spin and (1)H NMR spin-lattice relaxation measurements in the isotropic phase. While (1)H diffusion and (2)H relaxation times reveal a peculiar slow dynamic behaviour of banana-shaped mesogens compared with calamitic mesogens, the (1)H relaxation times seem to be affected by fast dynamics only. The origin of these dynamic features is discussed in terms of overall and internal molecular motions, in the frame of recent speculations concerning the formation of molecular clusters or aggregates in the isotropic phase of banana-shaped liquid crystals.     

端基含108个己氧基偶氮苯介晶基元三代树状碳硅烷液晶研究

用发散法合成以四碳硅烷为核心,周边含108个己氧基偶氮苯介晶基元(M3)端基的三代树状碳硅烷(D3)液晶,并用元素分析、核磁共振、激光解吸电离飞行时间质谱、红外光谱、紫外光谱、偏光显微镜、差示扫描量热(DSC)和X射线衍射法(WAXD)进行表征.D3为向列相液晶,与M3相同,三代(D3)、二代(D2)和一代(D1)树状物的相态由介晶基元的相态决定.D3的液晶态相行为是K79N136I132N,D3的熔点比M3的低19℃,D3的清亮点比M3的增加16℃,D3液晶态温区比M3宽35℃.     

Thermal behaviour under pressure of the thermotropic cubic mesogen 4'- n -alkoxy-3'-nitrobiphenyl-4-carboxylic acids

The thermal behaviour of members of a homologous series which exhibits the optically isotropic cubic phase, the 4'- n -alkoxy-3'-nitrobiphenyl-4-carboxylic acids having alkoxy chains containing 16, 20 and 22 carbon atoms (referred to as ANBC-16, -20 and -22, respectively) was investigated under pressures up to 200-400 MPa by high pressure differential thermal analysis. In the phase diagram of ANBC-16 obtained on heating, a triple point was estimated at 54 ±1 MPa and 205 ±1°C for the SmC, Cub and SmA phases. It was found that the X phase is formed on cooling under all pressures, while appearing on heating at high pressures above about 54 MPa. Thus the X phase appears monotropically between the SmA and Cub phases in the low pressure region and enantiotropically between the SmA and SmC phases under higher pressures. It is strongly suggested that the X phase is a columnar mesophase. For ANBC-20 and -22, the cubic phase tends to be destabilized with increasing pressure. The temperature region of the cubic phase of ANBC-20 becomes narrower with increasing pressure and a triple point for the SmC, Cub and I phases is estimated to be at about 309 MPa. On the other hand, the cubic phase of ANBC-22 is still observed at the highest pressure examined.     

Mesomorphic phase transitions of a series of D-phase compounds

Mesomorphic phase transitions of 4'-n-alkoxy-3'-nitrobiphenyl-4-carboxylic acids (ANBC) with numbers of carbons (n) in the alkoxy group ranging from 11 to 22 have been studied by differential scanning calorimetry (DSC) and polarizing optical microscopy. The D phase, a mesophase of particular interest through its being optically isotropic, was observed for the n = 17, 19, 20, 21, and 22 members of the ANBCs, as well as for the n = 16 and 18 members, as reported previously. The S_c-D phase transition temperature decreased with increasing n, so that the temperature range of the D phase extended over 64° at n = 22. In the n = 15 member, the D phase was certainly observed on first heating, but was not seen on subsequent cooling and second heating processes.     

Study of chemically inequivalent N(CH3)4 ions in [N(CH3)4]2ZnBr4 near the phase transition temperature using 1H MAS NMR, 13C CP/MAS NMR,and 14N NMR

The temperature dependences of the chemical shifts and intensities of ¹H, ¹³C, and ¹⁴N nuclei in tetramethylammonium tetrabromozincate, [N(CH₃)₄]₂ZnBr₄, were investigated using single-crystal nuclear magnetic resonance (NMR) and magic angle spinning (MAS) NMR spectroscopy to elucidate the structural geometry near the phase transition temperature. Based on the analysis of the ¹³C cross-polarization (CP)/MAS NMR and ¹⁴N NMR spectra, the two chemically inequivalent N(1) (CH₃)₄ and N(2) (CH₃)₄ ions were distinguished. Furthermore, the ¹⁴N NMR spectrum at the phase transition temperature indicated the existence of the ferroelastic characteristics of the N(CH₃)₄ ions.     

Phase behavior of an extended surfactant in water and a detailed characterization of the concentrated phases

The formation of microemulsions with triglycerides at ambient conditions can be improved by increasing the surfactant-water and surfactant-oil interactions. Therefore, extended surfactants were developed, which contain hydrophilic/lipophilic linkers. They have the ability to stretch further into the oil and water phase and enhance the solubility of oil in water. In this work, the phase behavior of a chosen extended surfactant (C(12-14)-PO(16)-EO(2)-SO(4)Na, X-AES) in H(2)O/D(2)O at high surfactant concentrations (30-100 wt %) and at temperatures between 0 and 90 °C is studied for the first time. The lyotropic liquid crystals formed were determined by optical microscopy, small-angle X-ray scattering (SAXS), and (2)H and (23)Na NMR, and a detailed phase diagram of the concentrated area is given. The obtained mesophases are a hexagonal phase (H(1)), at low temperatures and small concentrations, a lamellar phase (L(α)) at high temperatures or concentrations, a bicontinuous cubic phase (V(2)) as well as a reverse hexagonal phase (H(2)). To our knowledge, this is the first surfactant that forms both H(1) and H(2) phases without the addition of a third compound. From the (2)H NMR quadrupole splittings of D(2)O, we have examined water binding in the L(α) and the H(2) phases. There is no marked difference in the bound water between the two phases. Where sufficient water is present, the number of bound water molecules per X-AES is estimated to be ca. 18 with only small changes at different temperatures. Similar results were obtained from the (23)Na NMR data, which again showed little difference in the ion binding between the L(α) and the H(2) phases. The X-ray diffraction data show that X-AES has a much smaller average length in the L(α) phase compared to the all-trans length than in the case for conventional surfactants. At very high surfactant concentrations an inverse isotropic solution (L(2)), containing a small fraction of solid particles, is formed. This isotropic solution is clearly identified and the size of the reversed micelles was determined using (1)H NMR measurements. Furthermore, the solid particles within the L(2) phase and the neat surfactant were analyzed. The observed results were compared to common conventional surfactants (e.g., sodium dodecyl sulfate, sodium lauryl ether sulfate, and sodium dodecyl-p-benzene sulfonate), and the influence of the hydrophilic/lipophilic linkers on the phase behavior was discussed.     

Dielectric,viscous and elastic properties of nematogenic 1-(4- trans -propylcyclohexyl)-2-(4-cyanophenyl)ethane

This paper presents the results of measurements of the static and dynamic electric permittivity, the shear viscosity of a freely flowing sample, and the splay and bend elastic constants for 1-(4-trans -propylcyclohexyl)-2-(4-cyanophenyl)ethane (C3H7-CyHx-CH2CH2-Ph-C=N) (3CCPE). The static permittivity of the isotropic phase shows pre-nematic critical behaviour which is discussed in the frame of the fluid-like model of Mukherjee. From the temperature dependence of the dielectric relaxation time (corresponding to the molecular rotation around the short axis) and the shear viscosity, the strength of the nematic potential and the effective length of the 3CCPE molecule (in the isotropic phase), were estimated. The splay and bend elastic constants were determined from the voltage dependence of the capacitance of a planar nematic cell.     

Dielectric, viscous and elastic properties of nematogenic 1-(4- trans -propylcyclohexyl)-2-(4-cyanophenyl)ethane

This paper presents the results of measurements of the static and dynamic electric permittivity, the shear viscosity of a freely flowing sample, and the splay and bend elastic constants for 1-(4- trans -propylcyclohexyl)-2-(4-cyanophenyl)ethane (C 3 H 7 -CyHx-CH 2 CH 2 -Ph-C=N) (3CCPE). The static permittivity of the isotropic phase shows pre-nematic critical behaviour which is discussed in the frame of the fluid-like model of Mukherjee. From the temperature dependence of the dielectric relaxation time (corresponding to the molecular rotation around the short axis) and the shear viscosity, the strength of the nematic potential and the effective length of the 3CCPE molecule (in the isotropic phase), were estimated. The splay and bend elastic constants were determined from the voltage dependence of the capacitance of a planar nematic cell.     

Phosphorus-nitrogen compounds. Part 13. Syntheses, crystal structures, spectroscopic, stereogenic, and anisochronic properties of novel spiro-ansa-spiro-, spiro-bino-spiro-, and spiro-crypta phosphazene derivatives

The condensation reactions of N2Ox (x = 2, 3) donor-type aminopodand (4) and dibenzo-diaza-crown ethers (5, 6, and 9) with hexachlorocyclotriphosphazatriene, N3P3Cl6, produce two kinds of partially substituted novel phosphazene derivatives, namely, spiro-bino-spiro- (19) and spiro-crypta (21, 22, and 25) phosphazenes. The partially substituted spiro-ansa-spiro-phosphazene (11) reacted with pyrrolidine and 1,4-dioxa-8-azaspiro[4,5]decane (DASD) give the corresponding new fully substituted phosphazenes (14 and 16). Unexpectedly, the reactions of 23 and 24 with pyrrolidine result in only geminal crypta phosphazenes (26 and 27). The solid-state structures of 16 and 22 have been determined by X-ray diffraction techniques. The relative inner hole-size of the macrocycle in the radii of 22 is 1.27 A. The relationship between the exocyclic NPN (alpha') and endocyclic (alpha) bond angles for spiro-crypta phosphazenes and exocyclic OPN (alpha') bond angles for spiro-ansa-spiro- and spiro-bino-spiro-phosphazenes with 31P NMR chemical shifts of NPN and OPN phosphorus atoms, respectively, have been investigated. The structures of 10, 14, 16, 19, 21, 22, and 25-27 have also been examined by FTIR, 1H, 13C, and 31P NMR, HETCOR, MS, and elemental analyses. The 31P NMR spectra of 10, 21, 22, and 25 indicate that the compounds have anisochrony. In compounds 16 and 22, the spirocyclic nitrogen atoms have pyramidal geometries resulting in stereogenic properties.     

Dielectric studies of trans-4-n-octyl-(4-cyanophenyl)cyclohexane (8PCH) at ambient and high pressure

Dielectric relaxation studies have been performed on trans -4- n -octyl-(4-cyanophenyl)is cyclohexane (8PCH) at ambient and high pressure (0.1-175MPa). Two experimental set-ups were applied: a time domain spectrometer (TDS) covering the frequency range 10 MHz-5 GHz, was used to study the relaxation processes in the isotropic phase (at ambient pressure); an impedance analyser (1 kHz-13MHz) was used for high pressure measurements on both the nematic (N) and isotropic (I) phases. The low frequency (l.f.) relaxation process connected with molecular rotations about the short axis is hindered by the activation enthalpy of 70 kJ mol-1 and 32.6kJ mol-1 in the N and I phases, respectively, whereas the high frequency process (rotations about the long axis) has an activation enthalpy of 22.6kJ mol-1 (isotropic phase). From the pressure and temperature dependencies of the l.f. relaxation time tau, the activation volume, enthalpy and energy were calculated. It was found that the energy barrier hindering the molecular rotations around the short axis in the nematic phase is influenced to about one half by the volume effects. The nematic potential q was estimated at various pressures and comprises 10 20% of the total energy barrier. The pressure dependence of q enabled the calculation of the order parameter S (p) with the aid of old (Maier and Saupe) as well as recent (Coffey et al.) theoretical formulae.     

Possibility of isostructural condensed states of matter in the D phase of ANBC and the cubic mesophase of BABH: heat capacity of 4'-n-octadecyloxy-3'-nitrobiphenyl-4-carboxlic acid, ANBC(18)

Heat capacity measurements have been made on ANBC(18) at temperatures from 8 to 490 K by adiabatic calorimetry. All known phases were detected. The temperatures, enthalpies and entropies of transition were determined for the phase transitions observed. On the basis of the entropy of transition to the SmC phase from the D or cubic phases, it is pointed out that the D phase of ANBC and the cubic phase of BABH might be identical in nature. It is shown that the arrangement of 'molecular' cores has a higher degree of order in the isotropic (D and cubic) phases than in the SmC phase, whereas the terminal alkoxy chains are more disordered in the isotropic phases than in the SmC phase. The degrees of disorder in the D and cubic phases relative to the SmC phase are very similar in terms of the entropy of transition per methylene group. The inverted phase sequence in ANBC (SmC D on heating) and BABH (cubic SmC) can be accounted for in terms of the competing roles in the entropy between the molecular core and the chains.     

端基含12个己氧基偶氮苯介晶基元的树状碳硅烷液晶的合成

用发散法合成了周边含12个己氧基偶氮苯介晶基元(M3)端基的树状碳硅烷(D1),并用元素分析、氢谱、激光质谱、红外光谱、紫外-可见光谱、偏光显微镜、DSC和WAXD对产物进行表征.结果表明,D1为向列相,与M3相同,树状物相态由介晶基元相态决定,D1的液晶态相行为:K92N126I124N78K,D1熔点比M3降低了24～30℃,D1清亮点比M3提高了6～8℃,D1液晶态温区比M3加宽30～38℃,在树状物中观察到S=+2的高强向错.     

Dynamic properties of bicellar lipid mixtures observed by rheometry and quadrupole echo decay

In bicellar dispersions of 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) and 1,2-dihexanoyl-sn-glycero-3-phosphocholine (DHPC), the transition from isotropic reorientation to partial orientational order, on warming, is known to coincide with a sharp increase in viscosity. In this work, cone-and-plate rheometry, (2)H NMR spectroscopy, and quadrupole echo decay observations have been used to obtain new insights into the dynamics of phases observed in bicellar DMPC/DHPC mixtures. Samples with 25% of the DMPC component deuterated were used to correlate rheological measurements with phase behavior observed by (2)H NMR spectroscopy. Mixtures containing only normal DMPC (DMPC/DHPC) or only chain perdeuterated DMPC (DMPC-d(54)/DHPC) were used to refine rheology and quadrupole echo decay measurements respectively. The viscosity peaked at 4-9 Pa·s, just above the isotropic-to-nematic transition, and then dropped as samples were warmed through the nematic-to-lamellar transition. Quadrupole echo decay times above the nematic-to-lamellar transition were significantly longer than typically observed in the liquid crystalline phase of saturated lipid multilamellar vesicles. This may indicate a damping of slow bilayer undulations resulting from the coupling of opposite bilayer surfaces by DHPC-lined pores.     

The Silicides M4Si4 with M = Na,K, Rb,Cs, and Ba2Si4 – NMR Spectroscopy and Quantum Mechanical Calculations

The Zintl phases M₄Si₄ with M = Na, K, Rb, Cs, and Ba₂Si₄ feature a common structural unit, the Si₄^4– anion. The coordination of the anions by the cations varies significantly. This allows a systematic investigation of the bonding situation of the anions by ²⁹Si NMR spectroscopy. The compounds were characterized by powder X‐ray diffraction, differential thermal analysis, magnetic susceptibility measurements, ²³Na, ²⁹Si, ⁸⁷Rb, ¹³³Cs NMR spectroscopy, and quantum mechanical calculation of the NMR coupling parameter. The chemical bonding was investigated by quantum mechanical calculations of the electron localizability indicator (ELI). Synthesis of the compounds results for all of them in single phase material. A systematic increase of the isotropic ²⁹Si NMR signal shift with increasing atomic number of the cations is observed by NMR experiments and quantum mechanical calculation of the NMR coupling parameter. The agreement of experimental and theoretical results is very good allowing an unambiguous assignment of the NMR signals to the atomic sites. Quantum mechanical modelling of the NMR shift parameter indicates a dominant influence of the cations on the isotropic ²⁹Si NMR signal shift. In contrast to this a negligible influence of the geometry of the anions on the NMR signal shift is obtained by these model calculations. The origin of the systematic variation of the isotropic NMR signal shift is not yet clear although an influence of the charge transfer estimated by calculation using the QTAIM approach is indicated.     

季铵盐型双子表面活性剂C14-s-C14·2Br的聚集行为

用1H NMR弛豫、2D NOESY研究了双子表面活性剂14-s-14胶束在重水溶液中的聚集行为. 1H NMR自旋-晶格、自旋-自旋弛豫实验表明, 联结基团质子及其邻近的亚甲基质子的运动受到严重限制, 表明这些质子形成胶束疏水核的壳层；而远离极性头的疏水质子的运动则相对自由, 说明其位于胶束的内部. 14-s-14系列(s=2, 3, 4)的弛豫实验结果还表明, 联结基团越短, 分子的碳氢链在疏水核中的排列越紧密. 与14-4-14的对应单链表面活性剂TTAB相比, 它们的分子运动更受限制. 14-4-14的2D NOESY 谱给出了与16-4-16类似的交叉峰信息, 这表明14-4-14同16-4-16一样, 形成了表面不平滑的球形胶束. 因此, 烷烃链的长短对胶束中分子的排列方式没有影响.     

Synthesis, Crystal Structure and Antibacterial Activities of 3-[（2-Hydroxy-4-diethylamino-phenyl）methylenehydrazinocarbonyl]-4-hydroxy-6-methyl-2（1H）-pyridinones

1 INTRODUCTION Recently, compounds containing pyrazole, imida- zole, triazole (including benzotriazole), pyridine, tetrazole and indole have attracted much interest because of their fungicidal activity, plant-growth regulating activity and antibacterial activity[1～3]. Schiff bases also constitute a good type of biolo- gically active substructures[4～7]. Studies of pyri- dine Schiff base-type fungicides have been repor- ted[8]. However, some structures of pyridine com- pounds containing h…     

Influence of alkoxy tail length on the self‐organization of hairy‐rod polymers based on mesogen‐jacketed liquid crystalline polymers

A series of hairy‐rod polymers, poly{2,5‐bis[(4‐alkoxyphenyl)oxycarbonyl]styrenes} (P‐OCm, m = 1, 2, 4, 6, 8, 10, 12, 14, 16, and 18) were designed and successfully synthesized via free radical polymerization. The chemical structure of the monomers was confirmed by elemental analysis, ¹H NMR and ¹³C NMR. The molecular characterizations of the polymers were performed with ¹H NMR and gel permeation chromatography. The phase structures and transitions of the polymers were investigated by the combination of techniques including differential scanning calorimetry, wide‐angle X‐ray diffraction, polarized optical microscopy, and rheological measurement. The experimental results revealed that the self‐assembly behaviors of P‐OCm changed with the increase in m. First, the P‐OCm (m = 1, 2) showed only a stable liquid crystalline phase above T_g. Second, with the increasing length of alkoxy tails, the P‐OCm (m = 4, 6, 8) presented a re‐entrant isotropic phase above T_g and a liquid crystalline phase at higher temperature. Third, the P‐OCm (m = 10, 12, 14, 16, 18) exhibited an unusual re‐entrant isotropic phase which was separating SmA (in low temperature) and columnar phases (in high temperature). It was the first time that mesogen‐jacketed liquid crystalline polymers formed smectic phase, re‐entrant isotropic phase, and columnar phases in one polymer due to the microphase separation and the driving force of the entropy. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012