吡唑啉衍生物有机电致发光器件中激基复合物的发射

以两种吡唑啉衍生物为空穴传输材料(HTM)和BBOT为电子传输材料组成双层器件, 获得了相对于组成材料的荧光光谱红移和宽化的电致发光. 双层器件和HTM∶BBOT等摩尔混蒸薄膜的光致发光及电致发光测量表明, 该谱带来自HTM/BBOT界面激基复合物的发射, 根据器件的能级图, 激基复合物的类型为BBOT的激发态BBOT⁽与基态的HTM相互作用的复合物. 用HTM∶BBOT混合发光层增加器件中激基复合物的形成界面, 提高了器件的发射性能.     

新型三嗪桥连的双1,8-萘酰亚胺衍生物的合成及其光物理行为

以1,8-萘酰亚胺和三聚氯氰为主要原料, 合成了两种由三嗪环桥连的双1,8-萘酰亚胺化合物3 和5. 采用紫外-可见光谱和荧光光谱等手段考察了两种化合物在不同溶剂中的光物理行为. 与参比化合物N-丁基-1,8-萘酰亚胺相比, 在二氯甲烷、三氯甲烷和甲醇等极性溶剂中, 化合物3和5除了在短波区(λ<400 nm)存在1,8-萘酰亚胺的特征荧光发射峰外, 在长波区(>450 nm)均产生一个较强的新荧光发射峰, 表现出分子内激基缔合物的光物理行为. 与化合物5相比, 由于化合物3特殊的构象异构, 其荧光强度发生严重的猝灭. 在非极性溶剂甲基环己烷中, 化合物5 由于存在较强的分子间氢键作用而聚集, 受激后形成了较稳定的分子间激基缔合物, 但未观察到明显的分子内激基缔合物的形成. 在甲苯溶剂中, 化合物3和5与甲苯分子形成了激基复合物, 并未形成分子内激基缔合物. 进一步研究3和5的固态激发态性质, 发现化合物3和5的固体薄膜受激后分别在465和469 nm处出现激基缔合物的特征荧光发射峰.     

双层有机电致发光器件中的激基复合物发射及特性

以两种常用的芳香二胺TPD和NPB为空穴传输材料(HTM)和BBOT为电子传输材料组成双层器件,获得了相对于组成材料的荧光光谱红移和宽化的电致发光.用光致发光表征了这种发射来自激基复合物,并用器件的能级图说明激基复合物的类型为BBOT的激发态BBOT^*与基态的HTM相互作用的复合物.比较TPD和NPB的分子结构和能级表明,分子具有有利的构型和取向比合适的能级更容易形成激基复合物.     

酸度及溶剂极性对两亲配体紫外-可见光谱的影响

研究了溶剂生和溶液的酸度对两亲配体Ｎ－十六烷基－８－羟基－２－喹啉甲酰胺（ＨＬ）紫外－可见光谱的影响。在碱性介质中,ＨＬ的吸收带＾１Ｂｂ、＾１Ｌａ和＾１Ｌｂ均产生红移;在酸性介质中,ＨＬ的吸收带不仅红移,而且＾１Ｌｂ带分开明为两个吸收峰。ＨＬ存在明显的浓度效应。非极性和弱极性溶剂对ＨＬ的紫餐可见光谱的影响服从Ｂａｙｌｉｃｓ方程;极性溶剂对ＨＬ的紫外可见光谱的影响服从ＭｃＲａｃ方程。     

纳晶的制备及其光谱的尺寸依赖性

用再沉淀法制备了纳米晶体,向体系中加入水溶性高分子聚乙烯醇（PVA）可有效地抑制纳晶的生长,从而制得了稳定的具有不同粒径的纳晶.光谱研究表明,随着纳晶粒径增加,由于纳晶中分子间相互作用的变化,其吸收峰和激发峰位置都发生了红移,同时纳晶中激基缔合物的荧光发射峰强度减弱,荧光寿命有所延长.     

Nd^3＋对菠菜光合作用的影响

研究了Nd^3 对菠菜生长及光合作用的影响。结果表明Nd^3 处理能明显增加菠菜生长量，提高叶绿素含量和光合效率。UV—Vis谱表明Nd^3 处理使叶绿素a soret带蓝移2nm，Q带红移lnm，Soret峰强与Q带峰强比增加，FT-IR谱表明叶绿素a卟啉环峰形变宽，显示形成了Nd^3 -叶绿素a。Nd^3 处理使菠菜叶片PSⅡ的荧光发射峰蓝移12nm，且PsⅡ的荧光发射峰强度明显下降，表明Nd^3 结合到了PsⅡ蛋白色素复合物上．提高了电子传递效率。     

同分异构体对形成激基复合物的影响——对位和邻位苯二甲酸二甲酯与乙基咔唑形成的激基复合物

对位和邻位苯二甲酸二甲酯与乙基咔唑都能形成激基复合物,但对位苯二甲酸二甲酯对乙基咔唑荧光的淬灭常数大于邻位苯二甲酸二甲酯对乙基咔唑的淬灭常数,所形成的激基复合物的荧光谱带的峰位置也不一样,前者的峰位置的波长较短,它们形成激基复合物的速度常数K_3和分解为原初状态的速度常数K_4也都不一样,对位的两个速度常数分别大于邻位的两个速度常数,这些实验结果无法用已有的理论进行统一的解释,因此我们假定了一个新的模型,这一模型可以满意地解释现有的实验结果。     

高分子链对激发态芳烃和胺相互作用的影响

本文研究了在激发状态下芳烃(受体)和脂肪胺(给体)的相互作用以及高分子链在其中的影响。结果表明,高分子胺与不带高分子链的胺相比,其对激发态芳烃的淬灭速度和形成激基复合物的能力都强得多,并且激基复合物光谱发生明显红移。     

N,N′-双-β-萘甲基哌嗪分子内激发态复合物形成的混合溶剂效应

本文测定了N,N′-双-β-萘甲基哌嗪(DMNP)在苯与乙腈混合溶剂中的荧光光谱。在乙腈含量<5(mol·dm^-3)时,乙腈猝灭DMNP苯溶液的荧光符合Stern-Volmer方程,表明极性溶剂分子乙腈与DMNP分子内激基复合物存在着相互作用。随着乙腈含量的增加,DMNP分子内激基复合物(exci-plex)荧光的猝灭与红移以及分子内激基缔合物(excimer)的逐步形成则仅与体系的极性有关。文中还讨论了DMNP激发态复合物形成的机理。     

2,6-萘二甲酸二甲酯与一些二甲基萘所形成的激基复合物

2,6-萘二甲酸二甲酯与一些二甲基萘可以形成激基复合物。本文通过稳态和动态荧光光谱研究了这类激基复合物的形成与分子结构的关系。结果表明,尽管这些二甲基萘的电离能基本相同,但因取代基位置不同使分子中电荷分布不同,从而影响了激基复合物的形成能力。     

Effects of Hydrogen-bonding Interaction and Polarity on Emission Spectrum of Naphthalene-Triethylamine in Mixed Solvent

The effects of the protic and aprotic polar solvents on the emission spectrum of the naphthalene-triethyl-amine system in THF were studied under conditions of steady-state illumination. The fluorescence spectrum of the naphthalene-triethylamine system consists of two emission bands, the fluorescence band of naphthalene (band A, 329 nm) and the emission band of the exciplex(band B, 468 nm). The intensities of both the emission bands decrease with increasing the solvent polarity. The intensity of band B also decreases due to the hy-drogen-bonding interaction between triethylamine and protic solvent, while that of band A increases. It is thus suggested that the quenching of naphthalene fluorescence by triethylamine in THF occurs through the charge transfer and electron transfer reactions. The spectral changes upon the increase of solvent polarity can be explained by the dependences of the equilibrium constant between exciplex and ion-pair and the rate constant for the electron transfer reaction from triethyl.amine to the excited naphthalene on the rel.ative permittivity of solvent. It is shown that the formation of intermolecular hydrogen-bonding between triethylamine and protic solvent suppresses the quenching reaction by the decrease in free amine. Acetonitrile has only a polar effect and trichloroacetic acid only a hydrogen-bonding(or protonation) effect, while alcohols have both the effects. The effects of alcohols could be separated into the effects of solvent polarity and intermolecular hy-drogen-bonding interaction quantitatively.     

Exciplex formation and energy transfer in a self-assembled metal-organic hybrid system

Exciting assemblies: A metal-organic self-assembly of pyrenebutyric acid (PBA), 1,10-phenanthroline (o-phen), and Mg(II) shows solid-state fluorescence originating from a 1:1 PBA-o-phen exciplex. This exciplex fluorescence is sensitized by another residual PBA chromophore through an excited-state energy-transfer process. The solvent polarity modulates the self-assembly and the corresponding exciplex as well as the energy transfer, resulting in tunable emission of the hybrid (see figure).     

Polar and Hydrogen-Bonding Effects of Alcohols on the Emission Spectrum of Styrene–Triethylamine System

The emission spectra of styrene (ST)–triethylamine (TEA) systems were measured under steady-state illumination conditions in some tetrahydrofuran (THF)–protic solvent mixtures. The fluorescence spectrum of the ST–TEA system in THF consists of two bands (band A at 304 nm (fluorescence of ST) and band B at 460 nm (emission from an exciplex)). The intensity of band A increased and that of band B decreased with increasing amounts of protic solvents in THF–protic solvent mixtures. The increase in the intensity of band A was explained by the decrease in the concentration of free amine owing to the hydrogen-bonding interaction (or protonation) between TEA and protic solvents. The decrease in the intensity of band B was considered to be caused by the decrease in the concentration of free amine upon the addition of protic solvents and the enhanced conversion of the exciplex to an ion pair with increasing solvent polarity. The polar effect was expressed as a function of the relative permittivity of the solution.     

EXCITED STATE PROPERTIES OF THE N-(DEOXYGUANOSIN-8-YL)-2-AMINOFLUORENE ADDUCTS

The spectroscopic characteristics of adducts derived from the covalent binding of the carcinogen 2-aminofluorene to the C8 position of deoxyguanosine [N-(deoxyguanosin-8-yl)-2-amino-fluorene, dGuo-C8-AF], and from an adduct of similar structure formed with the synthetic polynucleotide poly(dG-dC).poly(dG-dC), were investigated. At 77 K both adducts are characterized by well-defined and rather narrow fluorescence emission spectra with maxima at 370 and 390 nm characteristic of the aromatic, monomolecular 2-aminofluorene (AF) residue. In contrast, at room temperature, the fluorescence is characterized by a broad, structureless emission band with a maximum at 460 nm in aqueous mixtures, shifting to 415 nm in solvents of lower polarity (100% propanol); the maxima are located at intermediate wavelengths in solutions of different propanol/water compositions, and this emission is attributed to an excited state complex (exciplex). The fluorescence quantum yield decreases when either the solvent polarity or the temperature are increased, varying from 5.4% (100% propanol) to 0.04-0.05% (100% H2O). The fluorescence decay profiles of dGuo-C8-AF adducts (measured at the National Synchrotron Light Source facility at the Brookhaven National Laboratory) can be roughly, but not exactly, modeled in terms of two exponential decay components in the range of about 0.3-1.0 ns with the propanol concentration greater than 60%; at lower propanol concentrations, a single short lifetime is observed and in 100% water solutions its value is 0.08 ns. The shorter lifetime, favored in solvent mixtures of higher polarities, is attributed to an exciplex with significant charge-transfer character.(ABSTRACT TRUNCATED AT 250 WORDS)     

Solvent-induced intramolecular exciplex fluorescence of β-naphthylmethyl amine

Intramolecular exciplex fluorescence of β-naphthylmethyl amine has been observed in polar media. The absence of exciplex fluorescence and the quenching of naphthalene-type fluorescence in hydrocarbon solvents is explained in terms of enhanced intersystem crossing. The crucial role the solvent can play in determining the energy and intensity of exciplex fluorescence is clearly demonstrated.     

Quencing of perylene fluorescence by Ag+ ions via exciplex formation

The fluorescence of perylene in alcoholic solution is dynamically quenched by AgClO₄ resulting in a new emission band with its maximum around 480 nm. Analysis of fluorescence decay curves at various emission wavelengths proves the formation of a perylene/Aa⁺ ion exciplex in the quenching reaction.     

聚酯聚醚嵌段共聚物与1,4-二咔唑环丁烷在激发态及基态的相互作用

<正> 聚酯聚醚嵌段共聚物具有十分良好的物理和机械性能,能加工成橡胶、纤维、塑料胶粘剂等,近年来也有作为医用高分子材料的报道。所以对聚酯聚醚嵌段共聚物的研究十分活跃。然而,有关其光物理性质的研究还很少见。本文报道了混合聚醚-聚酯嵌段共聚物(MPEE)与反式1,4-二咔唑环丁烷(1,4-DCC)在激发态和基态下的相互络合作用。结果表明,MPEE可以猝灭1,4-DCC的荧光,同时形成激基复合物。在分散     

A solvent isotope effect upon exciplex photochemistry

For several naphthylalkylamines, change of solvent from methanol to deuterated methanol (CH₃OD) leads to an increase in quantum yield of intramolecular exciplex fluorescence, an increase in exciplex fluorescence lifetime and an increase in naphthalene triplet yield. The solvent effect is explained by the relative abilities of the two solvents to form hydrogen (deuterium) bonds and to protonate (deuterate).     

STUDY ON THE PROTONATION MECHANISM OF 2,6-DIMETHYL NAPHTHALENE DICARBOXYLATE

By the study of absorption and fluorescence spectra and the lifetime of fluorescence at room and low temperatures of 2,6-dimethyl naphthalene dicarboxylate (DMN) in different concentrations of sulfuric acid, different interactions between molecules of DMN and sulfuric acid have been observed. These interactions have been revealed by the absorption spectra of charge transfer complex in the ground state, emission of exciplex, absorption spectra of hydrogen bonding interaction, absorption and emission spectra after proton transfer and different lifetimes before and after protonation. The interaction mechanism of DMN and sulfuric acid through first the CT complex and exciplex then hydrogen bonding and finally proton transfer is proposed.     

Unified interpretation of exciplex formation and marcus electron transfer on the basis of two-dimensional free energy surfaces

The mechanism of exciplex formation proposed in a previous paper has been refined to show how exciplex formation and Marcus electron transfer (ET) in fluorescence quenching are related to each other. This was done by making simple calculations of the free energies of the initial (DA*) and final (D+A-) states of ET. First it was shown that the decrease in D-A distance can induce intermolecular ET even in nonpolar solvents where solvent orientational polarization is absent, and that it leads to exciplex formation. This is consistent with experimental results that exciplex is most often observed in nonpolar solvents. The calculation was then extended to ET in polar solvents where the free energies are functions of both D-A distance and solvent orientational polarization. This enabled us to discuss both exciplex formation and Marcus ET in the same D-A pair and solvent on the basis of 2-dimensional free energy surfaces. The surfaces contain more information about the rates of these reactions, the mechanism of fluorescence quenching by ET, etc., than simple reaction schemes. By changing the parameters such as the free energy change of reaction, solvent dielectric constants, etc., one can construct the free energy surfaces for various systems. The effects of free energy change of reaction and of solvent polarity on the mechanism and relative importance of exciplex formation and Marcus ET in fluorescence quenching can be well explained. The free energy surface will also be useful for discussion of other phenomena related to ET reactions.