SYNTHESIS AND PROPERITIES OF SHISH-KEBAB-TYPE LIQUID CRYSTALLINE POLY（p-PHENYLENE）S

Abstract The novel shish-kebab-type liquid crystalline poly（p-phenylene）s were synthesized through Suzuki coupling reaction from 2,5-bis[（4-n-alkoxyl）benzoyloxy]1,4-dibromobenzene （monomer 1） and 1,4-benzenediboronic acid bistrimethylene cyclic ester （monomer 2）. Their structure and properties were characterized by GPC, DSC, X-ray diffraction and polarizing optical microscope （POM）. It was found that the polymers turned to liquid crystalline phase above their melting point. The melting point （Tm） of the polymers decreases when the length of the alkoxy tails of the mesogenic units increases. The mesophase was identified by X-ray diffraction method. The polymers could dissolve in common organic solvents and show strong blue fluorescence. The maximum absorption bands of polymers prepared from annealed films have large red-shift due to the spontaneous orientation of the liquid crystalline side chains. The same phenomena were also observed in the fluorescence spectra.     

PREPARATION AND CHARACTERIZATION OF SHISH-KEBAB TYPE LIQUID CRYSTALLINE POLY（p-PHENYLENEVINYLENE）

Novel shish-kebab type liquid crystalline poly（p-phenylenevinylene） derivatives were synthesized by Stille coupling reaction from 2,5-bis[（4-n-alkoxyl）benzoyloxy]1,4-dibromobenzene （monomer l） and 1,2-bis（tributylstannyl） ethylene （monomer 2）. The polymers with alkoxy groups are soluble in common organic solvents and exhibit blue fluorescence. Both the cast film and the annealed film have large red-shifts in fluorescence spectra and show yellow fluorescence. The polymers with CN and NO2 groups show poor solubility and green fluorescence. All the polymers possess liquid crystalline smectic phases. The melting point （Tm） of the polymers decreases when the length of the alkoxy tails of the mesogenic units increases. The polymers are easily aligned under a magnetic field of 10 Tesla. It is found that the conjugated backbone and LC side chain are aligned perpendicular and parallel to the magnetic field, respectively. The polymers show optical dichroism in fluorescence spectra, suggesting that they are available for advance materials with linear optical polarization.     

1-（（12-Bromododecyl）oxy）-4-（（4-（4-pentylcyclohexyl） phenyl）ethynyl） benzene：Liquid crystal with aggregation-induced emission characteristics

The luminescent liquid crystals （LLCs） are expected to solve the conflicts between the aggregation caused quenching and the requirement of aggregation or self-organization for LCs. Herein, we developed a new strategy of applying aggregation-induced emission （AIE） phenomenon to the molecular design of LCs towards LLCs. In this report, a calamitic liquid crystal based on tolane with AIE characteristics was successfully synthesized and the chemical structure was characterized by 1H, 13C NMR, and matrix-assisted laser desorption/ionization time-of-flight （MALDI-TOF） high-resolution mass spectra. The fluorescence behavior was studied by fluorescence spectroscopy and the liquid crystal phase behaviors were investigated by differential scanning calorimetry （DSC）, polarized optical microscopy （POM）. The crystal structure was obtained by X-ray diffraction crystallography with P1 space group. Results demonstrated that the sample was AIE active and the LC phases sequence during cooling was nematic, smectic C and smectic B phase.     

Photochromism of 36-Armed Liquid Crystalline Dendrimer

The photochromism of a 36-armed liquid crystalline dendrimer D6 was briefly described in this paper. The molar absorption coefficient, photoisomerization and photo back-isomerization of D6 in solution were investigated by UV/Vis absorption spectra. The results indicate that the photochromism and photo back-isomerization of D6 in chloroform （CHC13） and tetrahydrofuran （THF） solutions are in accordance with the ftrst order kinetics. The photochromism rate constants of D6 are 101 sI, it is 107 times larger than that of side-chain liquid crystalline polymers containing the same azobenzene moieties.     

SYNTHESIS AND CHARACTERIZATION OF LIQUID CRYSTAL POLYESTERS WITH T-SHAPED TWO-DIMENSIONAL MESOGENIC UNITS(Ⅲ)*

A new series of liquid crystal polyesters with T-shaped two-dimensional mesogenic units weresynthesized by melt polycondensation of the diacetates of 2-(4'-alkoxy -phenyl)-hydroquinones with 4,4'-alkylenedioxydibenzoic acid. The polymers were characterized by using polarized microscopy, DSC and X-ray diffraction. It was realized that all the polymers have nematic thermotropic liquid crystallinecharacteristics. The melting temperature (T_m) and isotropization temperature (T_i) of the polymers changeregularly with varying lengths of the alkoxy side group and the length of the alkylene group in the main chainin company with an even-odd effect. The mesophase temperature range also varies regularly with the polymerstructure. It is shown that the mesophase range has been widened.     

Spectral studies of the interaction between sanguinarine and guanosine

The interaction between sanguinarine and guanosine was investigated by using UV-vis and fluorescence spectra at pH 7.2. The binding of sanguinarine to guanosine was substantiated by the hypochromism and bathochromism in the absorption spectra and the emission quenching in fluorescence spectra. The fluorescence lifetime results, the varieties of the fluorophore absorption spectra and the decrease of the binding constant with the increasing temperature all indicate that the fluorescence quenching is static. The ratio and constant of the binding cytidine to sanguinarine are 2 and 6.44 × 10^7, respectively. The result shows that the binding of sanguinarine to guanosine is not only exothermic but also entropy-driven with △H=-8.53kJ/mol, AS = 0.12 kJ/（molK）, and AG =-44.57 kJ/mol at 298.15 K.     

Poly（meta-phenylene） Derivative with Rigid Twisted Biphenyl Units in Backbone： Synthesis, Structural Characterization, Photophysical Properties and Electroluminescence

A soluble poly(meta-phenylene)derivative with rigid twisted biphenyl unit was synthesized by the Yamamoto coupling reaction.The polymer is soluble in common organic solvents,and the number-average molecular weight is about 6500.The UV-Vis and quantum chemical calculation indicate that the different conformation segments named "conformers" exist in the polymer backbones;it was also further confirmed by the single crystal X-ray diffraction study of the dimeric model compound.The π-π transition of biphenyl segments of twisted and planar conformations made the polymer exhibit a strong absorption around 256 nm and a weak absorption at about 300 nm.Furthermore,the polymer exhibits a strong UV photoluminescence at 372 nm when the excitation wavelengths are longer than 300 nm.The ultraviolet-emitting electroluminescence(EL)device with the single layer structure shows EL λmax of the derivative at 370 nm.     

STUDY ON LIQUID CRYSTALLINITY OF POLY(N-VINYLCARBAZOLE)

The liquid crystallinity of poly(N-vinylcarbazole) was studied by using powder X-ray diffraction, polarized opticalmicroscopy, and differential scanning calorimetry. The results show that the lower molecular weight fractions of this polymerdo not form a liquid crystalline phase, while the samples of sufficiently high molecular weight do form a mesophase attemperatures above the glass transition. The lowest value of the degree of polymerization for PVK to form a stable liquidcrystalline phase was found to be in the range of 150 to 200, significantly higher than the value of 50 for most conventionalside chain liquid crystaline polymers.     

PREPARATION OF LOW MOLECULAR WEIGHT POLY（GLYCIDYL METHACRYLATE） BY PHOTOPOLYMERIZATION

Low molecular weight poly（glycidyl methacrylate）s （PGMAs） were prepared by photopolymerization in ethyl acetate, with benzophenone （BP） as photoinitiator, and triethylamine （TEA） as hydrogen donor. The existence of semipinacol dormant end groups in PGMA was confirmed by FT-IR and ^1H-NMR, and the content of the semipinacol dormant groups was determined quantitatively by ^1H-NMR measurement. The effects of various thctors, such as reaction time, BP concentration and monomer concentration on the synthesis of the polymers were investigated systematically. The molecular weights of the polymers were also investigated with GPC. It is shown that increasing BP concentration and decreasing irradiation time and monomer concentration led to a significant decrease of the molecular weights.     

Preparation and Characterization of Aromatic Polybenzoxazoles Copolymers Containing 2,6-Naphthalene Units

A series of polybenzoxazoles(co)polymers bearing crankshaft units in the main chain was synthesized by the conventional solution polycondensation of 4,6-diaminorescinol dihydrochloride, terephthalic acid (TA) and 2,6-naphthalene dicarboxylic acid(NDA). All of the polymers show lyotropic liquid crystal behavior in polyphosphoric acid (PPA) and methanesulfonic acid (MSA). The polybenzoxazoles exhibit an excellent thermal resistance although the crankshaft monomer has been introduced into the polymer backbone. The temperature for the 5% weight loss of all the polymers is above 600 ℃. The X-ray diffraction analysis results show that the series of the polymers has a high crystallinity. The introduction of NDA makes a slight decrease in the thermal resistance of the polymers. The maximum absorption peak in the UV-Vis spectra can be adjusted according to the amount of 2,6-naphthalene units in the polymers, which indicates the potential application of the polymers as optoelectrie materials.     

聚苯类共轭聚合物的合成及荧光特性研究

聚苯类共轭聚合物的合成及荧光特性研究李建科阳明书漆宗能王佛松（中国科学院化学研究所工程塑料国家重点实验室北京１０００８０）关键词聚对苯，共轭聚合物，吸收光谱，荧光光谱，发光共轭聚合物在非线性光学、光电化学池、二次电池等方面有着广泛的应用前景，近...     

Linearly polarized white fluorescence from shish-kebab type liquid crystalline poly(P-phenylenevinvlene)s with (P-phenylene)s as kebab

Liquid crystalline(LC) polymers with a shish-kebab-type moiety on their cross-conjugated(p-phenylene)s-poly(p-phenylenevinylene) s main chains were synthesized through Gilch polymerization in order to develop a kind of polymers available for linearly polarized white-light-emitting from single chain.In this system,the 2,5-bis(4’-alkoxyphenyl)benzene as the "kebabs" connects with poly(p-phenylenevinylene)(PPV) main chain backbone using its molecular gravity center and the PPV as the "shish" or "skewer"(the "shish-kebab").The polymers possess desirable properties such as excellent solubility and liquid crystalline properties.To drop the "kebabs" of the 2,5-bis(4’-alkoxyphenyl)benzene into the orientation microgroove of aligned polyimide film,not only the "shish" of polymer main chain can be aligned by the virtue of orientation of "kebabs" but also the uniform cross-conjugated structure between the "kebabs" and "shish" can be broken. Then,the alignment of the polymer main chain showed yellow light emission and was also accompanied by orientation of the LC side chains showing blue light emission,this gave rise to a notable linearly polarized white fluorescence.     

一类含萘环结构的聚酯酰亚胺液晶聚合物的结构与性能研究

利用Higashi芳香聚酯直接缩聚法的原理,采用分步投料的方法,以N,N′-1,6-亚己基-双苯偏三酸酰亚胺二酸(IA6)、6-羟基-乙-萘甲酸(HNA)和4,4′-二羟基二苯酮(DHBP)为单体原料,合成了一系列聚酯酰亚胺共聚物.用核磁共振(NMR)、差热分析(DSC)、偏光显微镜(PLM)、广角X射线衍射(WAXD)、热重分析(TGA)等手段对所合成的聚酯酰亚胺的液晶行为、结构以及热性能进行了表征.研究结果表明,当HNA投料量占单体总投料量高于33mol%时,所得聚合物均呈明显的向列型热致液晶特性.但是,此类液晶聚合物仅在升温过程中出现液晶的相转变,而在降温过程中并未观察到液晶的相转变行为.由DSC结果分析可知,此类聚合物具有较高的玻璃化转变温度(Tg)和较低的熔融温度(Tm),有望成为一类既具有较低加工温度又有较高使用温度的液晶聚合物材料.     

含电子给体-受体的交叉共轭聚合物合成及其离子传感性能

在芴苯结构主链中引入苯并噻唑作为电子受体、侧链上引入N,N-二丁基苯胺作为电子给体,通过Suzuki反应制备了新型交叉共轭聚合物P1,同时合成主链中不含苯并噻唑的芴苯类共聚物P2作为对比;对两者的化学结构和光物理性质进行了表征,并研究了聚合物对离子的光学传感性能.实验和模拟计算结果均表明,P1中存在着强的分子内电荷转移效应;引入电子给体和受体(D-A)能够有效地调控交叉共轭聚合物的光学特性,这种D-A型交叉共轭聚合物是一类潜在的具有荧光增强性能的化学传感材料.     

H2Pc-VOPc二元体系的制备和表征

八十年代,国外Canon,IBM,HP,Ricoh,Xerox等公司开发出由计算机控制、数字扫描、激光成像的高分辨激光打印机,并逐渐占领市场。这种激光打印机具有印刷质量高、寿命长、印刷速度快、版面可任意调制、噪音小等特点。     

双-(磷酸二甲酯)合铜的红外光谱与晶体结构

合成了单元化学式为-Cu[(CH_3O)_2PO_2]_2-的铜(Ⅱ)与磷酸二甲酯的配位聚合物。测定了4000—100 cm~(-1)谱区内的红外光谱, 讨论了某些谱带的归属, 解释了配位化合物形成后的光谱变化。由单晶X-射线衍射法确定此配合物的晶体属单斜晶系,空间群为P2_1/c, 晶胞参数a=1.0704(4), b=0.5093(2), c=1.9737(6) nm; β=96.23(3)°; V=1.0696(6) nm~3; Z=4. M=313.5, F(000)=636e, D_c=1.943 g·cm~(-3)。铜与五个配体中的五个非酯氧配位成四角锥体, 相邻两铜原子以对称的“O—P—O”桥和不对你的“O—P—O”桥相连, 形成一维链状配位聚合物。     

铜(Ⅱ)离子与神经红蛋白的相互作用

利用紫外可见吸收光谱、荧光光谱、同步荧光光谱及圆二色(CD)光谱研究了铜髤离子与神经红蛋白(NGB)的相互作用。结果表明,Cu2+离子使NGB在280nm处的紫外吸收增强,说明Cu2+与NGB发生了相互作用;Cu2+使NGB内源性荧光发生猝灭,其猝灭机制为静态猝灭;同步荧光光谱表明,Cu2+使色氨酸微环境的疏水性有所降低,Cu2+对NGB的作用位点更接近于色氨酸;CD光谱显示Cu2+没有引起NGB二级结构明显的变化。     

含液晶基团的聚对亚苯基亚乙炔基类交替共聚物的合成、表征及性能研究

合成了两种含氰基联苯液晶基团的新型聚对亚苯基亚乙炔基(PPE)类交替共聚物,并对其进行了结构表征和性能研究.示差扫描量热仪(DSC)和偏光显微镜(POM)的结果证明了在液晶单元含量较大时聚合物才会出现明显的液晶形态.荧光光谱表明,在降温前后液晶聚合物的发光光谱发生了明显的变化.同时,对聚合物进行能量转移研究发现随着溶液浓度的增加,Frster能量转移更加完全;另外,利用原子力显微镜(AFM)对聚合物降温前后的形态变化进行了观察.结果表明,液晶性质可以导致聚合物形态的变化进而带来发光光谱的改变,为今后制备液晶可控型发光聚合物提供了理论依据.     

SYNTHESIS AND CHARACTERIZATION OF LIQUID CRYSTAL POLYMERS WITH T-SHAPED TWO-DIMENSIONAL MESOGENIC UNITS (Ⅱ)*

A series of liquid crystalline polymers with T-shaped two-dimensional mesogenic unitswere synthesized via low temperature solution polycondensation of 2-(4'-alkoxy-phenyl)hydroquinone with various diacyl dichlorides. The polymers were found to be nematic andshown thermotropic liquid crystalline behaviors through observations using DSC, polarizedmicroscopy and X-ray diffraction. The melting temperature T_m and the isotropizationtemperature T_i of the polymers change regularly with varying of the monomer structures.