含空间位阻侧链取代炔烃的合成及其催化聚合

设计并合成了具有较大空间位阻侧链的取代炔烃2-炔丙氧基-1,4-对苯二甲酸二甲酯单体,分别采用WCl6,WCl6-SnPh4和[Rh(nbd)Cl]2催化体系使其聚合,考察了不同催化剂对聚合的影响.采用红外光谱和核磁共振等技术对单体及聚合物结构进行了表征,并用紫外光谱和荧光光谱研究了所得聚合物的光学性能.结果表明,使用[Rh(nbd)Cl]2催化剂时得到的聚合物是高反式结构,荧光光谱中除了侧基的350 nm发射峰外,还在429 nm处存在较弱的共轭主链发射.使用WCl6-SnPh4催化体系得到的聚合物由于较高的顺式含量,主要是侧基的发射,而较大侧基位阻使主链共轭降低.尽管存在较短的间隔基,引入较大空间位阻侧基仍然迫使聚合物主链扭曲,顺式结构中侧基空间位阻的影响更大.     

含不同柔性链的(甲基)丙烯酸酯类液晶高分子的合成及其液晶行为研究

通过改变侧链中柔性间隔基的长度,合成了一系列含有两个手性中心的侧链液晶（甲基）丙烯酸酯类聚合物.红外、核磁和GPC表征各中间体、单体及聚合物的结构和分子量.通过DSC和热台偏光显微镜系统地研究了单体和聚合物的液晶态织构.结果表明,含有六个碳的柔性间隔基的丙烯酸酯类聚合物表现为近晶SA和手性近晶SC^＊液晶相.     

水溶性磷酸盐功能化的聚芴作为细胞色素c的荧光生物传感器

通过Suzuki偶联反应,在水／DMF体系下制备了一种阴离子水溶性聚芴衍生物——聚[2,7-二溴-9,9-二（6-磷酸基己基）芴-alt-苯基]钠盐（PFHPNa）．聚合物PFHPNa具有良好的水溶性和强的蓝色荧光发射．通过比较不同淬灭剂对PFHPNa和已报道的具有不同侧链长度的聚[2,7-二溴-9,9-二（6-磷酸基己基）芴-alt-苯基]钠盐（PR,PNa）的淬灭效率,研究了侧链长度对荧光传感性能的影响．对于小分子淬灭剂（甲基紫精（MV^2＋）和间5,10,15,20-四（N-甲基-4-吡啶基）卟吩（TMPyP4））而言,聚合物PFHPNa由于较长的侧链长度而表现出较低的灵敏度．     

侧链取代的芴苯共聚物的光电性质及其溶剂化效应研究

采用Suzuki偶联聚合的方法合成了一系列化学结构明确、侧基性质(长度、体积、给/吸电子性质)不同的Hairy-Rod型芴苯共聚物. 通过光谱、电化学和模拟计算等手段研究了苯环上不同性质的侧基取代芴苯聚合物的发光性质、电化学性质和溶剂化效应等, 同时研究了侧基性质的变化对这些物理性质的影响规律. 苯环上烷基侧链长度的改变对取代共聚物的光谱、电化学和发光效率等影响很小|而随着苯环上烷氧基侧链长度的增加, 聚合物的光谱稳定性逐渐增强, 荧光发射光谱中的0-1转变逐渐被抑制, 荧光发射半峰宽减小. 苯环上取代侧基的给/吸电子性质变化对聚合物的光电性能具有全面的影响, 改变取代侧基的给/吸电子性质可调节芴苯共聚物的发光颜色和HOMO, LUMO能级以及HOMO-LUMO能隙等, 因此, 通过引入不同性质的侧基可实现对此类聚合物光物理性能的调控. 溶剂的极性对聚合物溶液的光谱性质具有显著影响, 溶液光谱随溶剂极性的增大逐渐向长波移动. 当聚合物本身带有强极性基团时, 在强极性溶剂中将发生聚合物分子链与溶剂分子间的强极性相互作用, 从而会引起更复杂的结果.     

以β-二酮连接的含生色团丙烯酰类单体及其饱和模型化合物的荧光行为

通过合成一系列同一分子中既含有给电子性荧光生色团又含缺电子性碳碳双键的烯类单体, 发现这类单体在相同生色团浓度下的荧光强度均明显低于相应的饱和模型化合物或聚合物[1～3]. 这种现象称为荧光结构自猝灭效应(SSQE), 以区别于浓度自猝灭现象. 对于电子状态与之相反的单体, 即含受电子性荧光生色团的乙烯基醚类单体, 也观察到了SSQE[4,5]. 进一步的研究结果表明, SSQE是光照条件下分子内电子给受体之间电荷转移作用的结果, 分子中电子给受体间的间隔基长度和溶剂的性质等都对SSQE有显著的影响[6]. 以往合成的含给生色团的丙烯酰类单体, 其电子给受体间是通过饱和脂肪链相连, 当生色团和受电子性碳碳双键之间以β-二酮结构相连时, 这类单体的荧光性质如何, 是否发生SSQE是我们的关注所在. 另一方面, β-二酮类化合物在一定波长光照射条件下, 常发生烯醇式与酮式的互变异构化. 虽然已有许多文献报道有关烯醇式-酮式互变异构过程中各种光谱的变化以及用核磁、红外、紫外等光谱手段研究烯醇式-酮式互变异构动力学, 但有关β-二酮类化合物互变异构过程中荧光光谱的变化的报道却很少[7～11]. 本文合成了以β-二酮连接的含二甲氨基苯基生色团的烯类单体, 1-(4-二甲氨基苯基)-4-甲基-4-戊烯-1,3-二酮(DMPDK)及其饱和模型化合物1-(4-二甲氨基苯基)-1,3-丁二酮(DMBDK), 研究了其光谱性质及光致互变异构行为.     

沉淀剂对含有氨侧基的聚苯撑乙炔发光性能的影响

通过单体4-[(2,5-二溴苯)乙炔基]苯胺和1,4-二乙炔基-2,5-二戊氧基苯之间的Sonogashira偶合反应合成了带有p-氨基苯乙炔基共轭侧基的聚对苯撑乙炔（(PAnPE）). 该共轭聚合物的THF溶液（(2××10-－5 mol•·L-－1）)在473和519 nm处呈现两个比较强的荧光发射峰. 通过调节在聚合物PAnPE-THF溶液中所加入三种沉淀剂（(甲醇、乙酸、稀盐酸溶液）)的体积比例, 来改变PAnPE分子链的聚集态结构, 进而研究对其发光性能的影响规律. 实验结果表明: 由于沉淀剂与聚合物PAnPE分子链之间相互作用能力与方式的不同, PAnPE两个荧光峰的发射强度因聚合物分子链聚集结构不同而呈现不同的变化规律, 这有助于实现在化学传感器中的应用.     

疏水作用对光化学和光物理过程的影响 Ⅶ.芘基烷基酮的荧光光谱及其在不良溶剂中的簇集

溶剂的极性对芘基烷基酮的单体荧光和激基缔合物荧光有很大影响,在非极性溶剂中单体荧光很弱,随着溶剂极性增大,单体荧光增强,单体荧光和激基缔合物荧光明显红移。利用芘基烷基酮荧光的这些性质研究了长链分子在二甲基亚砜-水(DMSO-H₂O)中的簇集现象。在浓度非常低的情况下,长链芘基烷基酮发射激基缔合物荧光,单体荧光也明显蓝移,表明芘基烷基酮形成了簇集体。长链饱和烷烃和芘基烷基酮发生共簇集,簇集体内的极性比环己烷的极性稍大。     

含硅宽禁带聚合物的合成及其光电性能研究

采用Suzuki聚合方法合成了以菲并咪唑为侧链的4种含硅宽禁带发光聚合物,并研究了这4种聚合物的光物理、电化学性质与电致发光性能.结果表明四苯基硅基团的引入能够得到宽的带隙,侧基上菲并咪唑的引入可以实现深蓝光发射.其中,基于聚合物P1的电致发光器件最大外量子效率为0.65%,最大发光效率为0.33 cd A~(-1),色坐标为(0.163,0.099).     

（＋）-甲基丙烯酸{2,5-双[4′-（（S）-2-甲基丁氧基）苯基]苯基}酯的合成及其螺旋选择性自由基聚合

设计合成了手性单体（＋）-甲基丙烯酸{2,5-双[4′-（（S）-2-甲基丁氧基）苯基]苯基}酯,并进行了自由基溶液聚合.相比于单体,聚合物的比旋光度有显著的同向增长,且在其圆二色光谱上对应于三联苯侧基以及酯基的吸收区域呈现明显的Cotton效应,说明其主链可能采取某一旋向占优的螺旋构象.研究了聚合条件对聚合物旋光性质的影响.结果表明,采用极性大的芳香族溶剂或增加单体浓度有利于获得旋光度大的聚合物;随聚合温度增加,聚合物旋光度先增加后减小,在80℃时聚合达到最大值.该聚合物比甲基丙烯酸三芳基甲基酯类光学活性螺旋链聚合物具有更好的化学结构稳定性和立体结构稳定性.     

具有温度敏感和荧光特性的侧链查尔酮共聚物的研究

采用2,2′-偶氮二异丁腈作为引发剂,将N-异丙基丙烯酰胺和4-甲基丙烯酰氧基-4′-二甲氨基查尔酮单体,在四氢呋喃溶剂中通过自由基共聚制备了一系列具有溶剂和温度双重敏感荧光特性的侧链查尔酮共聚物,并通过红外光谱、核磁共振氢谱和紫外-可见光谱对其结构进行表征,通过吸光度法测定了共聚物中查尔酮单元的含量.研究了侧链查尔酮共聚物的温敏性以及溶剂极性和温度双重敏感的荧光特性.结果表明,侧链查尔酮共聚物是一类具有最低临界溶解温度(LCST)的温敏性聚合物,其LCST温度随着共聚物中查尔酮含量的增加而降低;随着溶剂极性的增加,侧链查尔酮共聚物的紫外-可见最大吸收波长红移,其荧光发光波长红移并且发光强度先增强后降低,具有溶剂极性敏感的荧光特性;同时对比侧链查尔酮共聚物水溶液低温和高温下的荧光,发现低温下几乎无荧光,高温下其荧光得到明显增强,其荧光具有可逆的温度"开/关"特性。     

A case for using randomly labeled polymers to study long-range polymer chain dynamics by fluorescence

The process of excimer formation was studied for a series of pyrene end-labeled polystyrenes (PS(X)-Py 2 where X is the polymer molecular weight equal to 3, 4.5, 8, 12.7, and 14.6 K) and two series of polystyrenes randomly labeled with pyrene (CoE-PS and CoA-PS) in seven different solvents. The solvent viscosities ranged from 0.41 to 1.92 mPa x s, while the solvent quality ranged from good to poor solvents for polystyrene, as determined by intrinsic viscosity measurements. Steady-state fluorescence spectra of the pyrene-labeled polymers were acquired, and the excimer to monomer ratios showed that excimer formation increased strongly with a decrease in solvent viscosity. The monomer and excimer time-resolved fluorescence decays were also acquired and fitted globally to either the Birks' scheme or the fluorescence blob model (FBM) for the end- or randomly labeled polymers, respectively. All parameters reporting on the long-range polymer chain dynamics (LRPCD) obtained from the analysis of the fluorescence data acquired with the PS(X)-Py 2, CoE-PS, and CoA-PS series yielded virtually identical trends, demonstrating that these fluorescence experiments yield results that are internally consistent with one another. Considering the substantial advantages associated with the preparation and study of randomly labeled polymers, this report presents an appealing case for the use of randomly labeled polymers in the study of LRPCD.     

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.     

Physical Gels of a Syndiotactic Polystyrene Derivative with a Large Side-Chain Group

Summary: Gelation of syndiotactic poly(p-tert-butylstyrene) (sPTBS), a syndiotactic polystyrene (sPS) derivative having a larger side-chain group, was first examined with several solvents. The temperature-concentration phase diagram of sPTBS/trans-decalin gel clearly exhibited that sPTBS formed a polymer-solvent molecular compound with a ratio of 2.7 trans-decalin per one monomer unit. Our polarized fluorescence technique demonstrated that there appeared to exist more spacious free volume among sPTBS chains than sPS in a gel state. A cause determining the morphology of sPTBS with organic solvents was discussed in the present paper.     

Synthesis and characterization of side-chain liquid-crystalline poly(ether ester)s having p-substituted biphenyl mesogenic side groups

Several novel mesogenic spiro-orthoester monomers such as 1,6,10-trioxaspiro[4,5]decanes 4 , containing biphenyl mesogens at the C-8 positions of the five- and six-membered spirocyclic ring, through the alkylene spacers of different lengths were prepared by condensation reaction of the corresponding biphenyl mesogenic 1,3-propanediol 3 with 2,2-diethoxytetrahydrofuran, with 50–75% yields. Through cationic double ring-opening polymerization, carried out with boron trifluoride etherate as an initiator (5 mol % vs. monomer) in bulk at 150°C, spiro-orthoester monomers 4 afforded a novel class of side-chain thermotropic LC polymers with a poly(ether ester) as the main chain 8 . The liquid-crystalline properties of the spiro-orthoester monomers and the resulting polymers were examined by differential scanning calorimetry and optical polarized microscopy. Biphase separation was observed in the side-chain liquid-crystalline poly(ether ester)s upon annealing in the broad isotropic region. © 1998 John Wiley & Sons, Inc. J. Polym. Sci. A Polym. Chem. 36: 2439–2455, 1998     

Solvent effect on thermal degradation of plasticized para-substituted polystyrenes

The thermal effect on stability of a series of para-substituted polystyrenes with methyl, methoxy and α-methyl substituents in various solvents was studied in the temperature range of 298-363 K. They gave a monomer fluorescence as a minor part and excimer fluorescence as a major part. Thermal heating of para-substituted polystyrenes shows a decrease in both monomer and excimer fluorescences in all used solvents. Thermal heating causes a small fluorescence quenching effect at lower temperatures in solution but becomes very dominant at higher temperatures. Added terephthalate and phthalate plasticizers to these para-substituted polystyrenes caused a quenching of both monomer and excimer fluorescences without the formation of exciplex emission. The thermal quenching processes of the plasticized polymers were accompanied by a change in the structure of the fluorescence spectra at high heating temperatures. This may indicate that thermodestruction of these polymers starts from a random chain scission. The change in solvent polarity has considerable effect on fluorescence quenching but it has a minor effect on the thermal degradation of these polymers. The binding energies for excimer formation were calculated in the used solvents.     

How To Reach Intense Luminescence for Compounds Capable of Excited‐State Intramolecular Proton Transfer?

Photoinduced intramolecular direct arylation allows structurally unique compounds containing phenanthro[9′,10′:4,5]imidazo[1,2‐f]phenanthridine and imidazo[1,2‐f]phenanthridine skeletons, which mediate excited‐state intramolecular proton transfer (ESIPT), to be efficiently synthesized. The developed polycyclic aromatics demonstrate that the combination of five‐membered ring structures with a rigid arrangement between a proton donor and a proton acceptor provides a means for attaining large fluorescence quantum yields, exceeding 0.5, even in protic solvents. Steady‐state and time‐resolved UV/Vis spectroscopy reveals that, upon photoexcitation, the prepared protic heteroaromatics undergo ESIPT, converting them efficiently into their excited‐state keto tautomers, which have lifetimes ranging from about 5 to 10 ns. The rigidity of their structures, which suppresses nonradiative decay pathways, is believed to be the underlying reason for the nanosecond lifetimes of these singlet excited states and the observed high fluorescence quantum yields. Hydrogen bonding with protic solvents does not interfere with the excited‐state dynamics and, as a result, there is no difference between the occurrences of ESIPT processes in MeOH versus cyclohexane. Acidic media has a more dramatic effect on suppressing ESIPT by protonating the proton acceptor. As a result, in the presence of an acid, a larger proportion of the fluorescence of ESIPT‐capable compounds originates from their enol excited states.     

Photophysical properties of DASPMI as revealed by spectrally resolved fluorescence decays

Photophysical properties of 2-(4-(dimethylamino)styryl)-1-methylpyridinium iodide (DASPMI) in various solvents were investigated using time- and space-correlated single photon counting. DASPMI is known to selectively stain mitochondria in living cells.1,2 The uptake and fluorescence intensity of DASPMI in mitochondria is a dynamic measure of membrane potential. Hence, an endeavor has been made to elucidate the mechanism of DASPMI fluorescence by obtaining spectrally resolved fluorescence decays in different solvents. A biexponential decay model was sufficient to globally describe the wavelength-dependent fluorescence in ethanol and chloroform. While in glycerol, a three-exponential decay model was necessary for global analysis. In the polar low-viscous solvent water, a monoexponential decay model fitted the decay data. The sensitivity of DASPMI to solvent viscosity was analyzed using various proportions of glycerol-ethanol mixtures. The lifetimes were found to increase with increasing solvent viscosity. The negative amplitudes of the short lifetime component found in chloroform and glycerol at the longer wavelengths validated the formation of new excited-state species from the initially excited state. Time-resolved emission spectra in chloroform and glycerol showed a biphasic increase of spectral width and emission maxima. The spectral width had an initial fast increase within 150 ps and a near constant thereafter. A three-state model of generalized scheme, on the basis of successive formation of locally excited state (LE), intramolecular charge transfer state (ICT), and twisted intramolecular charge transfer (TICT) state, has been proposed to explain the excited-state kinetics. The presumed role of solvation dynamics of ICT and TICT states leading to the asymmetrical broadening and structureless fluorescence has been substantiated by the decomposition of time-resolved emission spectra in chloroform, glycerol, and ethanol/glycerol mixtures.     

Femtosecond time resolved fluorescence dynamics of a cationic water-soluble poly(fluorenevinylene-co-phenylenevinylene)

A recently synthesized cationic water-soluble poly(fluorenevinylene-co-phenylenevinylene) was studied by means of steady state and femtosecond time resolved upconversion spectroscopy in aqueous and EtOH solutions. Steady state spectroscopic measurements showed that the polymer emits at the blue-green spectral region and that aggregates are formed in concentrated polymer solutions. The fluorescence dynamics of the polymer in concentrated solutions, studied at a range of emission wavelengths, exhibited a wavelength dependent and multiexponential decay, indicating the existence of various decay mechanisms. Specifically, a rapid decay at short emission wavelengths and a slow rise at long wavelengths were observed. Both features reveal an energy transfer process from isolated to aggregated chains. The contribution of the energy transfer process as well as of the isolated chains and the aggregates on the overall fluorescence decay of the polymer was determined. The dependence of the energy transfer rate and efficiency on polymer concentration was also examined.     

溶剂对镓Corrole光谱性质的影响

合成了一系列周边取代的Corrole(1, 2, 3, 4)及其镓配合物1-Ga(Py)、2-Ga(Py)、3-Ga(Py)、4-Ga(Py),通过核磁共振氢谱(¹H NMR), 紫外-可见光谱, 电喷雾离子质谱(ESI-MS)的方法对其进行了表征. 研究了不同溶剂对这一系列自由Corrole 及镓Corrole 的紫外-可见(UV-Vis)吸收光谱, 稳态荧光和时间分辨荧光光谱, 将获得的荧光衰减动力学曲线采用单指数拟合并进行解卷积处理获得荧光的寿命值. 非（弱)极性溶剂对镓Corrole 紫外光谱的影响服从Bayliss 方程, 且镓Corrole 非辐射能量损失hc(ν¹_A-ν_F)与F(n)呈线性相关.     

Multicolor Emission from Non‐conjugated Polymers Based on a Single Switchable Boron Chromophore

Multicolor emissive and responsive materials are highly attractive owing to their potential applications in various fields, and polymers are preferred for their good processability and high stability. Herein, we report a series of new polymers based on a methacrylate monomer containing a switchable boron chromophore. In spite of their unconjugated nature, interestingly, the homopolymers from this monomer display rare multicolor fluorescence in solution that is highly dependent on the degree of polymerization (DP). With an increasing DP, the local concentration of the chromophore increases, leading to a higher propensity for switching the blue‐emitting tricoordinate boron chromophore to the red‐emitting tetracoordinate one. The homopolymers also display temperature‐ and solvent‐dependent emission color change. Furthermore, pure white‐light emission could be achieved in various solvents by precisely tuning the homopolymer molecular weight, or in films/solid state by copolymerizing the emissive boron monomer with non‐emissive monomers in an appropriate ratio.