半花菁衍生物分子非线性光学性质的理论研究

采用有限场(FF)/PM3方法对半花菁衍生物的第一超极化率和分子前线轨道性质进行了计算.结果表明,半花菁衍生物分子的第一超极化率主要与D-π-A结构有关,σ-烷基链对分子第一超极化率的影响很小,并且分子第一超极化率与分子前线轨道HOMO和LUMO能级差ΔEHL呈较好的线性关系.     

聚皂凝胶在溶液中的溶胀-消溶胀研究

聚皂是一类疏水改性的聚合物电解质,在其大分子结构中既带有亲水基团又带有疏水基团．通过一定程度的交联,可获得聚皂水凝胶．与近年来颇受关注的智能聚合物水凝胶一样,聚皂凝胶也表现出了相当的环境敏感特性．一般来说,聚合物水凝胶的ｐＨ敏感特性取决于分子链上所含...     

水煤浆添加剂与煤之间的相互作用规律研究 Ⅰ. 复合煤颗粒间的相互作用对水煤浆流变性的影响

使用12种不同分散剂对14种不同变质程度的煤进行了成浆性实验，分析了182个水煤浆(CWS)样品的流变性。结果表明，低变质程度和高灰煤浆多呈屈服假塑性，煤的性质起主导作用；变质程度高且灰分较低煤浆的流变性，主要依赖于分散剂的结构与性质；分子结构单元立体空间效应大，疏水基团与亲水基团呈立体间隔分布的分散剂，易形成屈服假塑性CWS；分子线度长，亲水基团与疏水基团呈线性间隔分布的分散剂，易形成胀塑性CWS。复合煤粒间的相互作用方式是决定CWS流变特性的关键。     

可溶性有机物对绿麦隆水溶解度和正辛醇/水分配系数的影响

土壤中的可溶性有机物(dissolved organic matter,DOM)其组分既具有亲水基团又具有疏水基团,而疏水基团易与有机化合物(如农药)形成一种不稳定的复合物,这种作用能明显的影响农药在土壤中的迁移和扩散。而正辛醇／水分配系数(n-octanol-water partition coefficient,Kow)是衡量有机化合物疏水性的重要依据。本实验选用广泛应用于麦田杂草     

高分子的折叠与聚集

总结了作者有关高分子折叠和聚集方面的工作。最初,作者研究了聚（N-异丙基丙烯酰胺）（PNIPAM）均聚物的折叠或叫做“线团-塌缩球的转变”,然后研究了含有疏水和亲水基团的PNIPAM共聚物的折叠。作者研究了疏水作用和亲水作用对折叠的影响,发现了融化球,有序线团等折叠过程中的中间态。另一方面,作者研究了两亲性高分子在水中的聚集与稳定。作者的结果表明,如果高分子链所形成的稳定聚集体为核-壳结构,则每个亲水基团所占有的面积为一个常数。如聚集体不是核-壳结构,即部分亲水基团分布在聚集体内部,则上述关系不再成立。随亲水基团含量的增加,聚集体将由球状变为超枝化结构。     

荧光素与电子给体/受体LB膜的制备、表征和光电性质

本论文涉及的问题是功能材料的分子设计、合成和按预定分子顺序取向排列的薄膜制备,是当前科学技术的前沿课题之一。合成了一系列荧光素衍生物包括由荧光素和电子给体(葱、吩唾嗓)及电子受体(紫精)组成的模型化合物和二元化合物,其中九种是具有亲水基团和疏水基团的长链烷烃衍生物。并在此基础上制备了LB膜,详细地研究了它们的成膜特性。运用荧光显微镜、透射电子显微镜、原子力显微镜、反射椭圆偏振法、X-射线衍射法、转移折叠法和偏振红外光谱法等多种现代仪器和分析方法,研究了膜的均匀度、平均折射率和厚度、功能团取向与LB膜的结构问题,并讨论了分子结构和取向与性能的关系。     

聚乙二醇-聚乳酸共聚物药物载体*

本文综述了聚乙二醇与聚乳酸共聚亲水改性的最新进展, 包括嵌段和星型结构聚乙二醇-聚乳酸共聚物(PEG-PLA)及其端基化衍生物的合成。同时概述了该共聚物以胶束、微粒、水凝胶和囊泡形式担载亲水、疏水及蛋白质类药物的应用,特别介绍了静电纺丝制备的PEG-PLA超细纤维载体及其释药特性。     

兼具有强阴离子性与疏水缔合性的丙烯酰胺三元共聚物

在微乳液介质中实施了丙烯酰胺 (AM)、苯乙烯 (St)、2 丙烯酰胺基 2 甲基丙磺酸钠 (NaAMPS)的共聚合 ,制备了既含有强阴离子性基团 (—SO3Na)又含有疏水基团 (St)的丙烯酰胺三元共聚物AM NaAMPS St;通过红外光谱法、紫外分光光度法及元素分析法对共聚物的结构及组成进行了表征 ;稀释外推粘度法测定了共聚物的特性粘数 ;测定了共聚物纯水溶液及盐水溶液的表观粘度 ;荧光探针法考察了三元共聚物的疏水缔合性以及离子基团对疏水缔合性的影响规律 .实验结果表明 ,在聚丙烯酰胺 (PAM )分子主链上同时引入强阴离子性基团与疏水基团后 ,阴离子的电粘效应与疏水基团的疏水缔合作用相互协同 ,会使共聚物水溶液的黏度显著提高 ;盐溶液对疏水缔合作用的增强效应与强阴离子基团对盐的较大容忍度相互结合 ,会使共聚物水溶液的抗盐性能明显得以提高 ;大分子链上的强阴离子基团磺酸根的存在 ,在一定程度上会削弱疏水基团之间的疏水缔合作用 ,即对疏水基团的疏水缔合行为会产生一定的负性影响 .     

二维紧密蛋白质链折叠序列的特性研究

采用完全计数法,研究了二维紧密蛋白质链在不同HP序列时的构象性质,特别是具有唯一基态能量的折叠序列的性质.对于具有N个单体的紧密蛋白质链,发现有一定比例的序列为折叠序列.在这些折叠序列中,疏水基团(H)的数目比亲水基团(P)多20%,并同200种真实蛋白质分子的疏水基团和亲水基团的结果进行了比较.对于不同的折叠序列,根据序列中其疏水基团的数目,把具有相同疏水基团数目的序列归在同一类,发现这样的序列在总的序列中的相对含量满足高斯分布.同时还对序列中H(或者P)团族大小及其分别进行了研究,发现折叠序列与无规随机序列不同.还研究了不同折叠序列在不同链长时的比热情况,发现其相转变温度TC主要与链长有关,与折叠序列无关.     

壳聚糖及其疏水衍生物自缔合行为*

过去几十年里,有关疏水改性聚电解质的理论和应用研究取得了长足的进展,通常认为其不同寻常的流变及溶解特性是由疏水基团的分子间或分子内相互作用产生的.本文综述了近年来有关壳聚糖及脱氧胆酸、烷基化和棕榈酰改性壳聚糖衍生物自缔合性质的研究进展,并简要介绍它们在药物释放和转基因领域的应用研究.     

三种双偶极半菁衍生物与H3PMo12O40自组装多层膜的研究

近几年来,静电自组装成膜材料的合成、薄膜的制备、表征和功能研究已得到了迅速发展[1～6],但对成膜材料分子结构与薄膜性质间构效关系的研究报道则较少[6].杂多化合物具有特殊的结构特征和氧化还原性质,而半菁化合物是备受关注的二阶非线性光学和光电转换材料[7,8],二者形成的     

A comparison of crystalline- and graft polymer-based chemosensors

Herein, we report a highly sensitive luminescent thin film chemosensor constructed out of a small-molecule donor/acceptor system. Two types of films were compared: one using a small-molecule crystalline donor/acceptor pair and the other using a donor-graft polymer/small-molecule acceptor pair. The acceptor selected for this proof of concept responds to acid, causing its absorption and emission bands to red-shift, which increases spectral overlap with the donor. This increase in overlap greatly enhances energy transfer from the acceptor to the donor. Signal amplification was ascertained by measuring the ratio of acceptor fluorescence when the donor was excited versus direct excitation of the acceptor. Both types of films exhibited large amplification. For the polymeric system, the mechanism of energy migration was investigated by the use of steady-state fluorescence spectroscopy. The mechanism was determined to be dominated by an exciton-hopping process.     

三种双偶极半菁衍生物与H3PM012040自组装多层膜的研究

近几年来，静电自组装成膜材料的合成、薄膜的制备、表征和功能研究已得到了迅速发展^[1-6]，但对成膜材料分子结构与薄膜性质间构效关系的研究报道则较少^[6]。杂多化合物具有特殊的结构特征和氧化还原性质，而半菁化合物是备受关注的二阶非线性光学和光电转换材料^[7，8]，二者形成的静电自组装薄膜是一类在光、电和催化等众多领域中有着潜在应用前景的纳米材料^[4]。本文报道了3种含磷钼酸根和不同结构的半菁阳离子的静电自组装膜，旨在探索不同阳离子对薄膜性质的影响。     

Biomolecular photodiode consisting of cytochrome c-adsorbed hetero-Langmuir–Blodgett films

Photoinduced electron transfer in biomolecular photodiode consisting of protein-adsorbed hetero-Langmuir–Blodgett (LB) films was investigated. Four kinds of functional molecules, cytochrome c, viologen, flavin, and ferrocene, were used as a second electron acceptor, a first electron acceptor, an electron sensitizer, and an electron donor, respectively. The hetero-LB film was fabricated by subsequently depositing ferrocene, flavin, and viologen onto the pretreated ITO glass. Cytochrome c-adsorbed hetero-LB films were prepared by soaking the hetero-LB films into the phosphate buffer solution containing cytochrome c. To verify the optimal adsorption conditions of cytochrome c molecules onto the viologen LB layers, the UV-absorption spectrum and atomic force microscopy observations of LB films were performed. Finally, the metal/insulator/metal structured molecular device was constructed by depositing aluminum onto the surface of the cytochrome c-adsorbed hetero-LB films. For photoelectric response properties, the current–voltage characteristic and photoswitching effect of the proposed molecular photodiode were investigated. To verify the charge shift, transient photocurrent of the molecular photodiode was measured.     

基于四硫富瓦烯衍生物导电LB膜研究概况

四硫富瓦烯(TTF)是具有可逆氧化还原性质的强电子给体, 由其衍生物制备的导电Langmuir-Blodgett (LB)膜可应用于分子材料及分子电子器件方面的研究. 简要综述了近年来具有代表性的基于TTF衍生物的导电LB膜及其可能用途.     

Proton translocation in monomolecular Langmuir-Blodgett films including 2-naphthol and 1,4-anthraquinone derivatives

The scope of the present work is the investigation of proton transport through monomolecular Langmuir-Blodgett (LB) films. The films were formed from amphiphilic molecules: 2-naphtholo-6-sulfonamide of dodecylamine (N) and 1,4-anthraquinono-2 sulfonamide of dodecylamine (A). The 2-naphthol derivative can act as a proton donor due to excited state proton transfer (ESPT) and the 1,4-anthraquinone group can play the role of proton acceptor because of protonation of the reduced form if it is present. Absorption and emission spectra of LB films containing N and A were registered and separated into component bands. Individual absorption and emission peaks observed were assigned to given forms of chromophores. The behavior of different component bands reflects the state of anthraquinone dependent on proton concentration. A correlation of rate and efficiency of ESPT, with changes of the spectra of A, may be expected to yield information concerning the transport of protons from N to A. The influence of the donor-acceptor distance, sample humidity, film arrangement and the presence of protonophores (Gramicidin A) on proton transfer is studied. Our results indicate that the proton can be transported through the film but its concentration vanishes at the distance greater than 30 A. The efficiency of proton transfer depends strongly on water content, film structure and the presence of ion channels.     

Langmuir-Blodgett films of a cationic zinc porphyrin-imidazole-functionalized fullerene dyad: formation and photoelectrochemical studies

Electron donor-acceptor dyad ensembles of a water-soluble cationic zinc porphyrin (viz., zinc tetrakis(N-methylpyridinium)porphyrin tetrachloride, Zn(TMPyP)) and a C60 derivative that bears an imidazole ligand (viz., 2-(phenylimidazolyl)fulleropyrrolidine, C60im) were assembled during the formation of Langmuir and then Langmuir-Blodgett (LB) films. Surface pressure versus surface area isotherms and surface pressure time profiles, as well as Brewster angle microscopic images documented that the Langmuir films formed were remarkably stable. Subsequently, these Langmuir films were transferred onto different solid substrates, by using the LB technique, for spectroscopic and photoelectrochemical characterization. The UV-vis spectroscopic investigations confirmed that the water-soluble Zn(TMPyP) was, indeed, transferred together with C60im in the LB films. Upon visible light illumination of these LB films, deposited on the ITO transparent conductive supports, a photocurrent generated in the C60im-Zn(TMPyP) system is ascribed to an efficient photoinduced electron transfer from the electron donor, porphyrin singlet excited-state to the electron acceptor, C60. Overall, internal photon-to-current efficiency, IPCE, of the photoanodic current generation (with ascorbate as a sacrificial electron donor) in the ITO/C60im-Zn(TMPyP)/ascorbate/Pt construct is over 5x larger than that of the photocathodic system (with methyl viologen, MV2+, as a sacrificial electron acceptor) in the ITO/Zn(TMPyP)-C60im/MV2+/Pt construct. Highly ordered film stacking favors vectorial electron transfer within the dyad, giving rise to the highest IPCE values of 2.5% determined for a photoanode that was composed of around 20 monolayer films.     

半花菁分子在LB多层膜中的取向研究

Polarized UV-visible absorption spectroscopy was used to investigate the inplane orientation of the hemicyanine molecules in Y-type Langmuir-Blodgett(LB) multilayers. We demonstrated for the first time that the dipping-induced molecular alignment was enhanced significantly with increasing the layer number due to the interlayer interactions. Polarized UV nanosecond pulses were used to control the photoinduced reorientation of the hemicyanine molecules. Thermal-isotropic process was accompaniedd by dissocition of the H-aggregate in hemicyanine LB multilayers.     

Molecular optical gating devices based on polymer nanosheets assemblies

We describe here a polymer nanosheet assembly that serves as a molecular photoswitching and optical exclusive OR (EXOR) logic gate. Separate polymer nanosheets (monolayers) containing phenanthrene, anthracene, and dinitrobenzene chromophore were prepared by the Langmuir-Blodgett technique (LB films). A bilayer-couple, consisting of phenanthrene (sensitizer) monolayer and dinitrobenzene (acceptor) monolayer, and the other couple, of anthracene monolayer and dinitrobenzene monolayer, were confirmed to function as a photodiode showing current rectification on light irradiation. The two photodiodes are connected as each photocurrent direction becomes opposite. In the polymer photodiode array (LB films), anodic photocurrent was observed when the anthracene was selectively excited. On the other hand, cathodic photocurrent was observed by selective excitation of the phenanthrene. Moreover, the output photocurrent displayed a very small value when the phenanthrene and anthracene were excited simultaneously. The performance is discussed for this gate's application to an optical EXOR logic gate.     

Exceptional Blueshifted and Enhanced Aggregation‐Induced Emission of Conjugated Asymmetric Triazines and Their Applications in Superamplified Detection of Explosives

A novel conjugated asymmetric donor–acceptor (CADA) strategy for preventing the redshift in photoluminescence, as well as preserving the merits of donor–acceptor architectures, was proposed and demonstrated for two triazine derivatives, which showed highly efficient, narrow, and blueshifted ultraviolet light emission in solid films along with special aggregation‐induced emission behavior. A mechanism of aggregation‐induced locally excited‐state emission by suppressing the twisted intramolecular charge‐transfer emission for the spectacular optoelectronic phenomena of these CADA molecules was suggested on the basis of both experimental measurements and theoretical calculations. By taking advantage of this special CADA architecture, fluorescent probes based on aggregates of conjugated asymmetric triazines in THF/water for the detection of explosives show superamplified detection of picric acid with high quenching constants (>1.0×10⁷ M ^?1) and a low detection limit of 15 ppb.