纳米二氧化硅为核的树枝状分子中荧光素激基缔合物和基态复合物的形成

在以二氧化硅为核的聚酰胺(PAMAM)树枝状聚合物的外端, 通过表面化学修饰引入了具有发射荧光能力的荧光素分子. 通过稳态荧光方法研究其固体和在水和丙酮的悬浮液中的光物理行为. 试验结果表明, 固体样品中, 在零代树枝状分子(G0F)中, 荧光发射主要是激基缔合物的发射, 在第一(G1F)和第二代(G2F)中只有基态复合物的发射. 在不同的悬浮液中不同的光物理行为表明, 树枝状分子中树枝链间的氢键作用的大小决定荧光素基团间是形成激基缔合物还是形成基态复合物. 这为设计和开发新型“壳-核”型纳米二氧化硅荧光传感器提供了有用的实验依据.     

聚醚砜激基缔合物的荧光光谱研究

本文研究了劳环在主链上的刚性高分子聚醚砜在二氯甲烷溶液中的荧光光谱.结果表明在适当的浓度下它也能形成分子间激基缔合物.     

紫外光辐照下聚醚砜激基缔合物形成的荧光研究

本文研究了聚醚砜(PES)的二甲基甲酰胺溶液的荧光光谱。发现在通常情况下,浓度在0.0004mg/mL～1mg/mL的范围内,只有聚醚砜的单分子荧光峰。但用波长为280nm的紫外光照射样品溶液能形成激基缔合物,且Ι_e/Ι_m与照射时间有关。     

稀溶液中环型聚苯乙烯的激基缔合物荧光效应

采用乙酸乙酯为环型和线型聚苯乙烯的非良溶剂, 确定了Mark-Houwink方程分别为[η]_r=1.91×10~(-2)·M~(0.607)和[η]_l=4.06×10~(-2)·M~(0.572)。研究了环型和线型聚苯乙烯的激基缔合物的荧光效应。通过稀溶液中环型和线型高分子线团在柔顺性上存在着差异, 解释了二者之间在荧光效应方面的差异, 并根据实验结果,确定了(I_E/I_M)c→0～M关系式分别为(I_E/I_M)r,c→0=1.91+3.40×10~(-6)M和(I_E/I_M)l,c→0=2.15+3.05×10~(-6)M。     

一类新型荧光化学敏感器形成激基缔合物的温度效应

对一类具有分子识别功能的荧光分子敏感器化合物，在水溶液中形成的分子内激基缔合物的温度效应进行了研究。进而提出该类化合物在水溶液中进行了内单体和分子内激基缔合物转化的机制。通过分析所得的热力学数据，同文献值相比较，推导出该类化合物在水溶液中可能存在的几何构型，为该类化合物在作为探针应用时提供理论依据。     

"标记"芘的激基缔合物荧光在水溶性高分子研究中的应用

首先介绍了芘的荧光发射光谱的特点及其激基缔合物荧光、然后给出了用芘标记高分子的各种方式和方法,讨论了水溶性高分子的”标记”芘形成激基缔合物的原理,评述了芘标记高分子箕缔合物荧光在水溶性分子疏水相互作用,静电相互作用、氢键、络合等研究中的应用,也介绍了芘标记激基缔的荧光在高分子凝胶体积相变、分子链运动等领域的研究进展。     

碱光诱导激基缔合物的振动结构的荧光发射

本文研究在1:1的甲醇-水二元溶剂, RNA及各碱基诱导的1,3-2(2-萘基)丙烷(1)的激光缔合物的振动结构的荧光发射, 振动结构的出现是由于RNA及各碱基诱导1分子按一定几何构象“冻结"使其振动能级固定的结果, 而高φ值下的疏水的相互作用只是促进了这一过程, 当加入β-CD时, 产生的振动结构会消失, 而加入α-CD则不受影响。     

碱光诱导激基缔合物的振动结构的荧光发射

本文研究在1:1的甲醇-水二元溶剂, RNA及各碱基诱导的1,3-2(2-萘基)丙烷(1)的激光缔合物的振动结构的荧光发射, 振动结构的出现是由于RNA及各碱基诱导1分子按一定几何构象“冻结"使其振动能级固定的结果, 而高φ值下的疏水的相互作用只是促进了这一过程, 当加入β-CD时, 产生的振动结构会消失, 而加入α-CD则不受影响。     

以激基缔合物为中间体的对—N,N—二甲氨苯乙烯和蒽乙烯的光…

研究了对－Ｎ，Ｎ－二甲氨苯乙烯和蒽乙烯生成的激基缔合物在不同极性溶剂中的荧光特性，发现其荧光发射波长随溶剂的极性增大向长波方向移动，且发现激基缔合物荧光量子产率的大小决定对－Ｎ，Ｎ－二甲氨苯乙烯和蒽乙烯的光环加成产物的产率，其中反式产物的相对产率随溶液极性增大而降低，并进一步探讨了此光环加成反应的机理。     

多足化合物的分子内激基缔合物形成及pH对其荧光的影响

研究了含萘脲基多足化合物溶液的稳态和瞬态光物理行为.由于分子内不同足间脲基的相互作用干扰了萘基的π-π叠合,使分子内萘基的激基缔合物生成受到影响.实验表明:由于三足化合物存在着给电子叔胺基团,因此当萘基被激发时、可因分子内的光诱导电子转移而导致荧光猝灭.正因如此,在三足化合物归一化后的稳态光谱中激基缔合物的发光强度很弱.用皮秒级单光子记数技术测得该化合物的瞬态荧光为三指数衰变过程.其中最长寿命的物种,即属于生成激基缔合物后再分解为萘激发态的部分仅占总量的4%,与稳态的结果相一致.工作表明对这类可用作荧光化学敏感器的三足化合物,如利用其激基缔合物的强度变化为其识别外来物种的敏感部位并不适合.相反,如引入的外来物种能影响化合物的分子内光诱导电子转移,进而影响萘基的发光强度,则是一较好的判别外来物种是否已进入主体的标志.     

Effects of Self-coiling of Organic Molecules on Intramolecular Exciplex Formation and Fluorescence Quenching in DX-H_2O Solvent System

ＩｎｔｒｏｄｕｃｔｉｏｎＨｙｄｒｏｐｈｏｂｉｃ ｌｉｐｏｐｈｉｌｉｃｉｎｔｅｒａｃｔｉｏｎｓ (ＨＬＩ)ｐｌａｙａｎｉｍｐｏｒｔａｎｔｒｏｌｅｉｎｃｈｅｍｉｃａｌａｎｄｂｉｏｃｈｅｍｉｃａｌｐｒｏｃｅｓｓｅｓｓｉｎｃｅｗａｔｅｒｉｓｔｈｅｃｏｍｍｏｎｍｅｄｉｕｍｉｎｐｈｙｓｉｏｌｏｇｉｃａｌｐｒｏ ｃｅｓｓｅｓ.1 4 Ｓｏｍｅｒｅｃｅｎｔｅｆｆｏｒｔｓｈａｖｅｂｅｅｎｄｅｄｉｃａｔｅｄｔｏｓｔｕｄｉｅｓｏｆｈｙｄｒｏｐｈｏｂｉｃｅｆｆｅｃｔｓｏｎｐｈｏｔｏｃｈｅｍｉｃａｌａｎｄｐｈｏ ｔｏｐｈｙｓｉｃａ…     

铕配合物OEL器件中激基复合物发光机制及消除

有机电致发光无论在科学研究还是在实际应用上都极大地吸引了人们的兴趣[1～3]。在研究的过程中,人们开发了许多的有机电致发光材料,在众多的材料中,稀土配合物有着明显的优势:由于稀土配合物能够利用配体三重态的能量,使得它的内量子效率在理论上能达到100%,而其它材料除了磷光染料[4,5]外内量子效率只能达到25%,同时稀土配合物中心离子的窄带发射有利于全色显示。目前,在有机电致发光领域实现高效纯红的窄带发光是一个很大的挑战,因为在基于颜色叠加原理的全色显示中,获得纯的红色发光是至关重要的。而三价稀土配合物中铕离子的红色发…     

Effects of Self—coiling of Organic Molecules on Intramolecular Exciplex Formation and Fluoresscence Quenching in DX—H2O Solvent System

Effects of self-coiling of organic molecules on intramolecular exciplex formation of compound I,in which the carbazole chromophore and terephthalic acid methylester acceptor group are linked by one (CH2)10 chain,and the decrease of the fluorescence intensities of compounds Ⅱ，Ⅲ，and Ⅳ,in which the carbazole chromophore and 3,5-dinitrobenzoate are connected by one aliphatic chain of (CH2)10 (Ⅱ），（CH2）12（Ⅲ）,or (CH2)4(Ⅳ）,have been studied in the dioxane (DX)-H2O binary system.The results show that self-coiling of organic molecules in DX-H2O facilitates intramolecular exciplex formation of I and induces the decrease of fluorescence intensities of Ⅱ,bacause of the proximity effect brought about by selfcoiling of organic molecules under hydrophobic-lipophilic interaction(HLI) between the excited carbazole chromophore and the acceptor.Since the similar effects are observed even when the concentration of the probes are less than their CAgCs(critical aggregate concentrations )in the DX-H2O mixture with the same φ values,formation of the intermolecular exciplex has been excluded.The effects are found to be strongly depended on φ values,indication that they are mainly driven by HLI.The properties of the acceptors can also affect the intramolecular exciplex formation.With terephthalic acid methylester moiety as the acceptor,the carbazole chromophore exhibits the fluorescence spectra of the exciplex,while with 3,5-dinitrobenzoate moiety as the acceptor,only the fluorescence spectra of excited carbazolyl chromophore are observed.     

柴油脱硫的机理研究以及反应中的溶剂效应

柴油的脱硫技术分为加氢脱硫和非加氢脱硫。在非加氢脱硫的研究中,氧化脱硫技术具有反应条件温和、不使用昂贵的氢气、投资和操作费用低等优点日益受到重视。文章介绍了柴油的脱硫技术的机理方面的研究进展。其中包括加氢脱硫的反应网络;以及氧化脱硫研究中,光化学氧化体系和有机过氧化物氧化体系中DBT的氧化机理。在不同的反应体系中,溶剂对含硫化合物的脱除也有很大的影响.     

Exciplex Formation and Excited State Deactivation of Difluoroborondipyrromethene (Bodipy) Dyads

Two series of geometrically‐related dyads are discussed based on the difluoroborondipyrromethene (Bodipy) unit, and incorporating covalently attached hydroquinone/quinone groups. These units are anchored directly, or via a phenylene spacer, to the Bodipy core at the meso position in one series ( BD‐MHQ , BD‐MQ , BD‐MPHQ , BD‐MPQ ), but for the second series the attachment site is the 2‐position ( BD‐SHQ , BD‐SQ , BD‐SPHQ , BD‐SPQ ). The compounds show various levels of fluorescence depending on the oxidation state of the appended group and the substitution pattern. In non‐polar solvents such as toluene, diethyl ether and dichlorobenzene, the S₁ state deactivation of the Bodipy unit in BD‐SPQ and BD‐MPQ is dominated by ^{1, 3}exciplex formation, which has not been reported for Bodipy derivatives so far. In the latter molecule, the decay of the exciplex is divided between population of the Bodipy triplet state (13 %–21 %) and ground state reformation. This partitioning is not seen for the side‐on substituted derivative, BD‐SPQ , and only ground state reformation is observed following decay of the exciplex. This difference in behavior is explained by the radical‐pair inter‐system‐crossing mechanism, which more effectively operates in BD‐MPQ because of the orthogonality of the donor‐acceptor units. In the more polar solvent CH₃CN all the quinone derivatives show fast formation of the charge‐separated state (k_CS) followed by slower charge recombination (k_CR). The ratio k_CS/k_CR≤80.     

甲基对硫磷农药标准物质溶剂效应探讨

利用气相色谱法研究甲基对硫磷农药标准物质的溶剂效应。通过GC–FID和GC–FPD对甲基对硫磷在甲醇、乙醇和丙酮3种不同溶剂中的气相色谱仪的响应进行了研究,考察了气相色谱仪检测器、溶剂种类、溶剂极性等因素对气相色谱法检测结果的影响。结果表明,相同浓度不同溶剂的甲基对硫磷溶液标准物质,在气相色谱仪的响应有显著性差异。     

Solvent Effects on Particle Formation in Hydrolysis of Tetraethyl Orthosilicate

Particle formation in ammonia-catalyzed hydrolysis of tetraethyl orthosilicate (TEOS) was studied in aqueous solvents that contained ethanol, 1-propanol or 1-butanol. The reactions were performed at a TEOS concentration of 0.2 kmol/m³, a H₂O concentration of 5 kmol/m³ and a NH₃ concentration of 1 kmol/m³. Average particle size was the largest for 1-butanol and the smallest for ethanol. No specific relation of the average diameter to hydrolysis rate was observed in the reactions. Difference in dielectric constant of the solvent and particle surface potential in the reactions indicated that the magnitudes of interparticle repulsion in the solvents corresponded with the order of the average particle sizes. This suggested that the particle sizes were dominated by the interparticle repulsion.     

亚硝基苯与甲醛的反应机理和溶剂效应的理论研究

采用密度泛函理论方法RB3LYP/6-311＋＋G(d,p)研究了亚硝基苯与甲醛在单重态势能面上分别在气相和溶剂中的反应机理. 找到两条反应通道: 协同机理和分步机理, 均生成实验产物N-苯基氧肟酸C6H5NOHCHO. 计算结果表明: 亚硝基苯与甲醛在气相中分步机理为主要通道. 采用导电极化连续介质模型研究了反应体系在水、乙醇、乙腈、二氯甲烷、四氢呋喃、环己烷溶液中反应的溶剂化效应, 这些溶剂可降低反应的活化能, 但反应对溶剂的极性不敏感. 无论在气相还是溶剂中, 亚硝基苯与甲醛的分步机理为优势通道.     

甲酸苯酯氨解反应的机理和溶剂效应的理论研究

采用密度泛函理论方法B3LYP/6-31G(d,p)研究了甲酸苯酯与氨在气相中的反应机理. 考虑了两条可能的反应途径: 中性协同的和中性分步的机理. 采用自洽反应场极化连续模型(CPCM模型)研究了反应体系在水、乙醇和乙腈溶液中反应的溶剂化效应. 计算结果表明气相和溶液中协同机理均是最优途径. 水、乙醇和乙腈溶剂可降低协同途径的活化能, 溶剂化效应的大小对溶剂的极性不敏感.     

Excimer and Exciplex Formation in Gold(I) Complexes Preconditioned by Aurophilic Interactions

Excimers and exciplexes are defined as assemblies of atoms or molecules A / A ′ where interatomic/intermolecular bonding appears only in excited states such as [ A ₂]* (for excimers) and [ AA ′]* (for exciplexes). Their formation has become widely known because of their role in gas‐phase laser technologies, but their significance in general chemistry terms has been given little attention. Recent investigations in gold chemistry have opened up a new field of excimer and exciplex chemistry that relies largely on the preorganization of gold(I) compounds (electronic configuration Au^I(5d¹⁰)) through aurophilic contacts. In the corresponding excimers, a new type of Au???Au bonding arises, with bond energies and lengths approaching those of ground‐state Au?Au bonds between metal atoms in the Au⁰(5d¹⁰6s¹) and Au^II(5d⁹) configurations. Excimer formation gives rise to a broad range of photophysical effects, for which some of the relaxation dynamics have recently been clarified. Excimers have also been shown to play an important role in photoredox binuclear gold catalysis.