Intramolecular Energy Transfer in Organized Assembles

A series of bichromophor compounds N — Hn — A( $ n = 2,4,6,8,10) has been synthesized by ourselves for the investigation of Energy Transfer. Bichromophore compound with γ — CD or β — CD aqueous solution are made up at the molar ratio of 1:1. It has been discovered that the efficiency of the energy transfer of the compound (n=10) in the γ—CD is obviously higher than that in the β — CD. This means that the cavity of the γ — CD is     

枝状体系中分子内光诱导能量转移*

枝状分子因其独特的化学结构,其光化学与光物理研究尤为引人注目。本文重点介绍了近二十年来报道的具有光诱导分子内能量转移的枝状分子的化学结构特点,分析了不同因素对光诱导分子内能量转移效率的影响;阐述了可以根据能量给体与受体的性质,利用化学策略对枝状体的分子内光诱导能量转移进行调控;概括了具有光诱导分子内能量转移性质的枝状分子的目前应用领域;总结了枝状体中分子内能量转移面临的关键科学问题,并展望了具有分子内能量转移的枝状分子的发展方向     

Intramolecular Energy Transfer in Dithienogermole Derivatives

Dithienogermole (DTG) has been applied as a useful building unit of optical/semiconducting materials for organic optoelectronic devices because of its extended conjugation, high chemical stability, and good emissive properties. Although DTG has two substituents on the Ge atom, the substituents have been limited to simple alkyl and aryl groups in previous work. In this work, to further uncover the new functionalities of this useful building unit, various π-conjugated groups were introduced on Ge of DTG. It was expected that the introduction of π-conjugated groups would give rise to efficient energy transfer between the substituents and the DTG core, which are in proximity and linked by a Ge atom. The thus-prepared DTG compounds with fluorene, terthiophene, and pyrene units on Ge possessed well-separated frontier orbitals on the substituents and the DTG core, as proved by the absorption spectra and DFT calculations. The substituted DTG derivatives showed clear emission only from the energy acceptor even though the energy donor was photoexcited. This indicated the highly efficient energy transfer in these compounds. We also prepared more π-extended compound DTGFl2-Ph with phenyl groups on the DTG thiophene rings. DTGFl2-Ph showed strong emission in the visible region with efficient energy transfer properties. These results clearly indicate the potential application of the present DTG system as optical functional materials.     

Solvent Reorganization Energy and Electronic Coupling for Intramolecular Electron Transfer in Biphenyl-Acceptor Anion Radicals

A novel algorithm was designed and implemented to realize the numerical calculation of the solvent reorganization energy for electron transfer reactions, on the basis of nonequilibrium solvation theory and the dielectric polarizable continuum model. Applying the procedure to the well-investigated intramolecular electron transfer in biphenyl-androstane-naphthyl and biphenyl-androstane-phenanthryl systems, the numerical results of solvent reorganization energy were determined to be around 60 kJ/mol, in good agreement with experimental datKoopman's theorem was adopted for the calculation of the electron transfer coupling element, associated with the linear reaction coordinate approximation. The values for this quantity obtained are acceptable when compared with experimental results.     

天线若丹明染料分子内能量与电荷传递的研究

染料三重态在染料激光的应用中起着重要作用，尤其是三重态一Z重态（T－T）吸收常常会造成谐振腔损耗＊．为了减少由基态吸收而造成的话振腔损耗，带有紫外吸收天线分子的三发色团染料已在研究问，2，5·二苯基螨喳（PP0）在紫外区（如308删）有很强的吸收，PPO－rhod．系列染料（见图1）在紫外区的吸收就很强，由PPO到若丹明母体的单线态一单线态（S功能量传递使这类三发色团染料具有较大的荧光量子效率，较小的基态重复吸收耗能卜，司．然而，在610N640nm区域中这些天线若丹明染料的激光输出效率远远小于若丹明Rh630＊，其原因正是…     

Electronic Energy Transfer in Linear Polymer Chains

The effect of the size of a polymer molecule and the character of the motion of its units in solution on the luminescence kinetics of chromophores attached to the polymer chain was studied.     

新颖的研究分子内远程电子转移和三线态能量转移过程的体系和方法

新颖的研究分子内远程电子转移和三线态能量转移过程的体系和方法ＡＮｅｗＳｙｓｔｅｍｆｏｒＳｔｕｄｉｅｓｏｎＩｎｔｒａｍｏｌｅｃｕｌａｒＬｏｎｇ┐ＤｉｓｔａｎｃｅＥｌｅｃｔｒｏｎＴｒａｎｓｆｅｒａｎｄＴｒｉｐｌｅｔＥｎｅｒｇｙＴｒａｎｓｆｅｒ１．论文名称...     

分子单重/叁重混合激发态碰撞传能中的量子干涉效应

量子干涉效应是基于量子力学波粒二象性原理,即微观粒子的运动皆具有波的特性而产生的一种干涉现象,故又称为物质波干涉.近年来,在分子的光激发、光解和光电离及碰撞过程中皆已观察到量子干涉效应,成为分子动态学领域研究热点之一.我们小组在国际上首次得到了单重/叁重混合激发态分子碰撞传能中的量子干涉的实验证据,从理论上导出了包括干涉相位角的传能截面公式,从实验上发展了激光双共振多光子电离光谱技术,用以测定了CO(A1П,v=0/e3∑-,v=1)与各种原子(He,Ne,Ar)及双原子分子H2,O2,N2,HCl碰撞传能的干涉角.其后又与李丽的小组合作,在热管炉中用激光双共振诱导荧光法观察到Na2(A1∑+uv=8/b3П0u,v=14)-Na碰撞中的量子干涉效应,证明了碰撞干涉效应的普遍性.近年来,在理论方面,我们发展了基于含时微扰的一级波恩近似量子散射方法,计算出了上述碰撞体系的干涉角θST,与实验值符合极好.本文指出虽然气池实验测得的干涉角θST是不同分子碰撞速度及碰撞参数的"平均"结果,但与理论计算的微分干涉角尚比较接近,可提供激发态分子碰撞相互作用势的重要而难得的信息.     

卟啉多枝分子合成与分子内能量转移、双光子吸收性能研究

以三苯胺或硝基苯为端基, 合成了三个卟啉多枝分子: 5-(4-硝基苯甲酰氧基)苯基-10,15,20-三-(4-溴苯基)卟啉(TPP-NO₂)、5-(4-硝基苯甲酰氧基)苯基-10,15,20-三-(4-二苯胺基-1-苯乙烯基)苯基卟啉(TPP-X₃)和5,10,15,20-四-(4-二苯胺基-1-苯乙烯基)苯基卟啉(TPP-X₄), 进行了红外光谱、核磁共振光谱和质谱表征. 比较研究了分子“枝”、“核”不同键合方式与不同对称结构对分子的线性光谱、非线性光谱以及分子内能量转移行为的影响. 在钛宝石激光器(800 nm)和Nd∶YAG倍频光(532 nm)泵浦下, 样品溶液均发出卟啉环特有的红色荧光——前者系双光子吸收机制“上转换”荧光, 后者则为双光子吸收与分子内能量转移机制“下转换”荧光. 飞秒Z-scan技术测得样品双光子吸收截面最大可达130 GM, 与四苯基卟啉(TPP)同等测试条件下的双光子吸收截面相比增大了两个数量级.     

On Theoretical Treatments of Electronic Excitation Energy Transfer

In this paper, we review the generalized Forster-Dexter theory to treat photoinduced electronic energy transfer for a system in dense media and for an isolated system (i.e., a system in the collision-free condition). Instead of expressing the rate of energy transfer in terms of spectral overlap, the expression of the energy-transfer rate constant is obtained by evaluating a Fourier integral involved in the energy transfer rate constant using the saddle-point method. In this way, the energy-gap dependence, and the effect of temperature and the isotope effect on the energy transfer can be easily studied. The effect of bridge groups connecting between donor and acceptor chromophores on the intramolecular energy transfer is also studied.     

含酪氨酸和色氨酸的肽内电子转移的溶剂重组能计算

基于连续介质模型，本文考察了多肽体系Trp-(Pro)n-Tyr (n=1,2) 从酪氨酸到色氨酸的分子内电子转移，并根据电荷定域的反应物和产物构型和线性反应坐标近似构造了电子转移的双势阱，通过势能曲线的交叉点确定了电子转移过渡态。本文重点讨论了电子转移溶剂重组能。根据作者的非平衡溶剂化理论和可极化连续介质模型编写了溶剂重组能计算程序并用于本文体系的计算。计算得到Trp-Pro-Tyr 和Trp-(Pro)2-Tyr.体系的溶剂重组能分别为20.89 kcal/mol和25.30 kcal/mol.     

卟啉-酞菁分子内能量传递和电子转移的溶剂效应

用稳态荧光光谱研究了以氧原子和哌嗪作为连接基的卟啉酞菁二元分子在不同溶剂中的分子内能量传递和电子转移过程结果表明;分子内的能量传递和电子转移是两个相互竞争的过程，在非极性溶剂中，激发单重态的能量传递是主要过程，而在极性溶剂中则以电子转移为主运用Rehm-Weller公式计算了两种二元化合物在不同溶剂中的电子转移反应的自由能变化△G0ET，表明溶剂的极性对电子转移反应的自由能变化△G0ET影响很大极性越大;体系中的电子转移反应的△G0ET、越负，电子转移反应越易进行由于电子转移过程较能量传递过程进行得快，所以表现为体系中能量传递效率降低而电子转移效率增大。两种二元化合物的能量传递效率（φEnT）利和电子转移效率（φET）随溶剂的极性的变化具有相同的变化趋势     

Efficient Intramolecular Energy Transfer between Two Fluorophores in a Bis‐Branched [3]Rotaxane

A bis‐branched [3]rotaxane, with two [2]rotaxane arms separated by an oligo(para‐phenylenevinylene) (OPV) fluorophore, was designed and investigated. Each [2]rotaxane arm employed a difluoroboradiaza‐s‐indacene (BODIPY) dye‐functionalized dibenzo[24]crown‐8 macrocycle interlocked onto a dibenzylammonium in the rod part. The chemical structure of the [3]rotaxane was confirmed and characterized by ¹H and ¹³C NMR spectroscopy and high‐resolution ESI mass spectrometry. The photophysical properties of [3]rotaxane and its reference systems were investigated through UV/Vis absorption, fluorescence, and time‐resolved fluorescence spectroscopy. An efficient energy‐transfer process in [3]rotaxane occurred from the OPV donor to the BODIPY acceptor because of the large overlap between the absorption spectrum of the BODIPY moiety and the emission spectrum of the OPV fluorophore; this shows the important potential of this system for designing functional molecular systems.     

Visible-Light Photocatalytic Intramolecular Cyclopropane Ring Expansion

Described herein is a new visible-light photocatalytic strategy for the synthesis of enantioenriched dihydrofurans and cyclopentenes by an intramolecular nitro cyclopropane ring expansion reaction. Mechanistic studies and DFT calculations are used to elucidate the key factors in this new ring expansion reaction, and the need for the nitro group on the cyclopropane.     

芳醚树枝形聚合物体系的设计合成及电子转移和三重态能量传递研究

<正>树枝形聚合物是一类具有特殊结构的大分子,通过可控合成,具有光捕获功能的官能团可以精确地分布在树枝形聚合物的核心或外围,甚至可以在支化单元的任何位置,随着代数的增加,官能团数目从核心向外围呈指数增长,树枝形聚合物的这种特殊结构被用来模拟光合作用中的光捕获体系.电子转移和能量传递是光合作用的关键过程,也是光化学研究的重要内容,因此,研究树枝形聚合物体系内的电子转移和能量传递是人工模拟光合作用的一个突破口,是目前相关研究工作的热点之一.本文设计合成了一系列一代到四代的芳醚树枝形聚合物,共24个新化合物,通过稳态、瞬态以及光化学反应的方法研究了芳醚树枝形聚合物体系内电子转移和三重态能量传递过程,得到了一系列有意义的研究结果:     

芳醚树枝形聚合物体系中电子转移和能量传递研究

树枝形聚合物英文名为dendrimer,是具有类似树枝状结构的化合物,由核心、内层支化单元和外围基团三部分组成.树枝形聚合物具有与光合作用体系相似的结构,作为模拟光合作用体系被广泛研究.电子转移是光合作用中的重要过程,研究树枝形聚合物体系中的电子转移与能量传递具有重要的意义.本论文设计合成了一系列芳醚树枝形聚合物,用光物理和光化学方法研究了芳醚树枝形聚合物体系中电子转移和能量传递过程,得到了一系列有意义的结果.     

Possibilities for Energy Pumping in a Radio-Frequency Quadrupole by Shifted Supersonic Gas Jet. Part I: Accelerated and Excited Atom Transmission

Generation of an ion beam and its transmission into a mass analyzer is one of central problems in mass spectrometry. The use of a narrowly directed supersonic gas jet has a number of advantages in comparison with other sampling methods. The aim of this work was to confirm the declared earlier properties of the jet formed at the outlet of a cylindrical channel when the free path length of gaseous atoms at the beginning of the channel is comparable with the channel diameter. The paper describes the ability of such a supersonic jet to conserve an additional energy of jet gas atoms. A significant influence of the temperature of the gas flow on the yield of cyclohexane fragment ions was found, cyclohexane being an admixture in the noble gas jet passing through an electron ionization ion source. A possibility of obtaining a flow of metastable electronically excited atoms inside the jet is also shown. The results of the work confirm the availability of the supersonic gas jet for the design of a high efficiency ion source inside the radio-frequency quadrupole at the input of the mass analyzer.