四苯基乙烯衍生物光物理和光化学研究

设计合成了一个四苯基乙烯衍生物Model-TPE,该化合物具有典型的聚集诱导发光（AIE）特性。¹HNMR、质谱以及高效液相色谱研究表明,有氧条件下Model-TPE经紫外光照射发生关环反应,生成二苯基取代菲衍生物,取代和未取代苯环侧关环反应得到异构体产物,提出了光氧化关环反应机理。本工作对TPE衍生物在发光及传感领域的应用有一定的指导意义。     

Photophysical and Photochemical Processes in Micellar Systems

A fascinating feature inherent to aqueous surfactant solutions is the phenomenon of self-organization: above a certain critical concentration (the critical micelle concentration, CMC) detergent molecules associate spontaneously to build up structural entities of colloidal dimensions called micelles. The architecture of these agglomerates is such that the interior contains the hydrophobic alkyl chain of the amphiphile while the hydrophilic head groups are located at the surface and are in contact with bulk water. In the case of ionic micelles the interface is charged giving rise to an electrical double layer and a potential difference of up to several hundred millivolts between the micellar pseudophase and water. Thus micellar systems are microheterogeneous in character: the electrostatic potential and polarity prevailing in the interior of the aggregate differ from those of the bulk aqueous phase. A particularly attractive aspect of photochemical studies in micellar systems is the possibility of organizing the reactants at a molecular level: by comparison of the data in micelles with similar data in homogeneous solution one can learn about the molecular details of a given reaction and establish which conditions favor one pathway or another. In simple surfactant systems differences in rate and efficiency of a reaction will often be controlled by local electrostatic potentials and the compartmentalization of the reagents within the surfactant aggregates. Through the latter effect the statistics of probe distribution over the micelles becomes important in controlling fast photochemical events. Functional micelles are distinguished by the fact that the surfactant molecule contains a group which itself participates in the photoprocess. These units are unique in that self-assembly often introduces striking cooperative effects.     

Photochemical and Photophysical Studies of 3-Amino-6-lodoacridine and the Inactivation of λ Phage

Abstract— The photochemistry and photophysics of 3-amino-6-io-doacridine (Acr-I) was studied. Photolysis (350 nm) of Acr-I (free base) generates products consistent with a free radical intermediate in methanol, benzene and carbon tetrachloride. The Acr-I hydrochloride is shown to bind to calf thymus DNA and to the self-complementary dinucleotide cytidylyl-(3′-5′)-guanosine (CpG) minidu-plex in a manner similar to that of proflavine (Acr-NH₂), a known DNA intercalator. The Acr-I is shown to more efficiently nick supercoiled plasmid DNA pBR322 upon 350 nm or 420 nm photolysis than Acr-NH₂. The efficiency of Acr-I-sensitized DNA nicking is not oxygen dependent. Photolysis of the Acr-I/(CpG)₂ complex leads to cleavage of the dinucleotide and to cytidine base release by selective damage to a specific ribose moiety. Dinucleotide cleavage occurs equally well in the presence or absence of oxygen, thereby eliminating a singlet oxygen- or peroxyl radical-mediated process. Photolysis of Acr-I in the presence of a mononucleotide (GMP) or a non-self-complementary dinucleotide (uridylyl-[3′-5′]-cytidine– UpC) does not lead to fragmentation and base release. Similarly, photolysis of the Acr-NH₂/(CpG)₂ complex does not lead to fragmentation and base release. The data indicate that photolysis of an iodinated intercalator bound to CpG or plasmid DNA generates an intercalated aryl radical and that the reactive intermediate initiates a sequence of reactions that efficiently nick nucleic acids. The inactivation of Λ phage sensitized by Acr-I with UV (350 nm) light is oxygen independent but with visible (420 nm) light is strongly oxygen dependent. The Acr-I fluoresces more intensely when excited at 446 than at 376 nm. Thus, UV photolysis may lead to C-I bond homolysis and free radical formation, a process that is not energetically feasible with visible light. The results demonstrate the difficulty of extrapolating model studies involving simple molecules and DNA to understanding the mechanism of viral inactivation with a particular sensitizer.     

Solvent Dependence of Photophysical and Photochemical Behaviors of Thioxanthen-9-one

The photophysical and photochemical behaviors of thioxanthen-9-one (TX) in different solvents have been studied using nanosecond transient absorption spectroscopy. A unique absorption of the triplet state \begin{document}$ ^3 $\end{document}TX\begin{document}$ ^* $\end{document} is observed, which involves two components, \begin{document}$ ^3 $\end{document}n\begin{document}$ \pi $\end{document}\begin{document}$ ^* $\end{document} and \begin{document}$ ^3 $\end{document}\begin{document}$ \pi\pi^* $\end{document} states. The \begin{document}$ ^3 $\end{document}\begin{document}$ \pi\pi^* $\end{document} component contributes more to the \begin{document}$ ^3 $\end{document}TX\begin{document}$ ^* $\end{document} when increasing the solvent polarity. The self-quenching rate constant \begin{document}$ k_{ \rm{sq}} $\end{document} of \begin{document}$ ^3 $\end{document}TX\begin{document}$ ^* $\end{document} is decreased in the order of CH\begin{document}$ _3 $\end{document}CN, CH\begin{document}$ _3 $\end{document}CN/CH\begin{document}$ _3 $\end{document}OH (1:1), and CH\begin{document}$ _3 $\end{document}CN/H\begin{document}$ _2 $\end{document}O (1:1), which might be caused by the exciplex formed from hydrogen bond interaction. In the presence of diphenylamine (DPA), the quenching of \begin{document}$ ^3 $\end{document}TX\begin{document}$ ^* $\end{document} happens efficiently via electron transfer, producing the TX\begin{document}$ ^\cdot $\end{document}\begin{document}$ ^- $\end{document} anion and DPA\begin{document}$ ^{\cdot} $\end{document}\begin{document}$ ^+ $\end{document} cation radicals. Because of insignificant solvent effects on the electron transfer, the electron affinity of the \begin{document}$ ^3 $\end{document}n\begin{document}$ \pi $\end{document}\begin{document}$ ^* $\end{document} state is proved to be approximately equal to that of the \begin{document}$ ^3 $\end{document}\begin{document}$ \pi\pi^* $\end{document} state. However, a solvent dependence is found in the dynamic decay of TX\begin{document}$^{{ \cdot ^ - }}$\end{document} anion radical. In the strongly acid aqueous acetonitrile (pH = 3.0), a dynamic equilibrium between protonated and unprotonated TX is definitely observed. Once photolysis, \begin{document}$ ^3 $\end{document}TXH\begin{document}$ ^{+*} $\end{document} is produced, which contributes to the new band at 520 nm.     

水溶性金属卟啉在水溶液中的光物理与光化学研究

研究了５种水溶性金属卟啉ＺｎＴＭＡＰＰ、ＺｎＴＭＰｙＰ、ＭｇＴＭＰｙＰ、ＺｎＴＢＰｙＰ和ＺｎＴＴＰＳ４的光物理（吸收光谱和荧光光谱、振子强度、荧光寿命、量子产率）、激发态氧化还原电势及光稳定性。结果表明ＭｇＴＭＰｙＰ是比ＺｎＴＭＰｙＰ更好的光敏剂。     

Photochemical and Photophysical Processes of N-Deacetyllappaconitine and Its Monohydrobromide in Aqueous Solutions

Chemistry of Natural Compounds - The photophysical and photochemical processes of N-deacetyllappaconitine (DAL) and its hydrobromide (DAL·HBr) in aqueous solutions were investigated. Their...     

Holographic Methods for the Investigation of Photochemical and Photophysical Properties of Molecules

Holography is most frequently thought of as a method of photography that results in three-dimensional images of the object being photographed. It is certainly true that this is the most visually spectacular aspect. But holography can also be used as a powerful tool for the investigation of a variety of photochemical and photophysical processes. These experimental techniques rely on the fact that small spatial modulations of a material's optical properties (index of refraction and absorption coefficient) can deflect an incident light beam into another direction. By following the growth or decay in intensity of this deflected beam, one can follow the underlying photochemical and photophysical processes producing the changes in optical properties. If a CW laser is used to produce the hologram one can use the technique to investigate solid state photochemistry. If a pulsed laser is used one can investigate a broad range of time dependent processes; energy transfer, diffusion, rotational relaxation, charge transport etc. Compared to conventional spectroscopic techniques the holographic method shows various advantages. So for example it is a highly sensitive zero-background technique and permits free choice of detection wavelength and detection beam intensity. As a result of information obtained using the holographic technique as a scientific tool, one can also find new classes of materials for the recording of holograms. This is the way in which two-photon four-level systems for hologram recording process gated on and off with an auxiliary source, and can be read with the infrared recording laser with no erasing of the hologram.     

芳氧基取代酞菁锌的合成及光物理化学性质

合成得到3-(5-氨基-萘氧基)邻苯二甲腈(C18H11N3O)、4-(5-氨基-萘氧基)邻苯二甲腈(C18H11N3O)、3-联苯氧基邻苯二甲腈(C20H12N2O)及4-联苯氧基邻苯二甲腈(C20H12N2O)4种未见报导的取代邻苯二甲腈,以此为前躯体合成了四[α-(5-氨基-萘氧基)]酞菁锌(C72H44N12O4Zn)、四[β-(5-氨基-萘氧基)]酞菁锌(C72H44N12O4Zn)、四[α-(联苯氧基)]酞菁锌(C80H48N8O4Zn)和四[β-(联苯氧基)]酞菁锌(C80H48N8O4Zn)4种未见报导的芳氧基取代酞菁锌配合物。通过测定它们的紫外-可见吸收光谱、荧光发射光谱,获得其最大吸收波长及其摩尔消光系数、最大发射波长、荧光量子产率(ΦF)、单线态氧量子产率(ΦΔ)及光降解速率常数并与其类似物进行了比较,探讨了它们的光物理光化学性质的构效关系。研究结果表明四[α-(联苯氧基)]酞菁锌在红光区具有大的摩尔消光系数,且具有较高的ΦΔ,有望开发成为光动力治疗用光敏剂。     

微环境对长链香豆素酯光化学和光物理过程的影响

疏水作用在胶束、膜的形成以及生命过程中起着重要的作用．疏水作用可促使长链分子相互簇集,造成局部浓度效应和分子的有序排列［１～３］,疏水作用对光化学和光物理过程的影响是一种微环境效应．本文合成了十六酸和十八酸－４－甲基－７－羟基香豆素酯,研究了它们在有...     

Primary Photophysical and Photochemical Processes in the Photolysis of 1,2-Dihydroquinolines in Different Solvents

The fluorescence lifetimes (τ_fl) of alkyl and alkoxy substituted dihydroquinolines (DHQ) were measured in hexane, isopropanol, methanol, and water. It was shown that τ_fl was determined by the solvent nature and weakly depended on substituents on the DHQ aromatic ring and heterocycle, with τ_fl being substantially lower in methanol than in the other solvents. The decrease in τ_fl in MeOH is caused by an increase in the rate constants of the photochemical reaction and nonradiative transitions in this solvent. The quantum yield of fluorescence in H₂O and MeOH, in which the photoinduced addition of the solvent molecules occurs, decreases with a decrease in the excitation wavelength within the limits of long-wavelength absorption band, thus providing strong evidence that the photochemical reaction proceeds from the unrelaxed excited state.     

Photophysical and Aggregation Studies of t-Butyl-Substituted Zn Phthalocyanines

Three potential photosensitizers for photodynamic therapy: tetra- t -butyl phthalocyaninato Zn(II), tetrakis-(1,1-dimethyl-2-phthalimido)ethylphthalocyaninato Zn(II), and tetrakis-(1,1-dimethyl-2-amino)ethylphthalocyaninato Zn(II), have been studied in homogeneous organic media. Dimerization constants and monomer and dimer spectra have been determined. Fluorescence, triplet and singlet oxygen quantum yìelds were measured and the photo-physical characterization of the triplet state was performed for the three dyes. These parameters were evaluated in connection with aggregation results.     

五羰基锰烷基化合物的合成及光化学反应研究

用五羰基锰钾盐和相应的卤代物在乙醚中的金属化反应合成了五羰基锰烷基合物 (CO)5MnR（R = CH3,p-CH2C6H4CH3, p-CH2C6H4OCH3 ）,产率达到72-93％,将这些化合物与1-2当量(CH3)2(C6H5)SiH和(CH3)(C6H5)2SiH的C6D6溶液在5℃光解,分别得到五羰基锰硅烷基化合物(CO)5MnSi(C6H5)(CH3)2和(CO)5MnSi(C6H5)2(CH3)（产率达到70-88％）。在光化学反应中,还观察到相应甲烷,对二甲苯,和对甲基苯甲醚的定量生成,以及少量的Mn2(CO)10（<2％-4％）,(CO)4MnH(SiR3)2（<9%）副产物。     

Biomimetic Chiral Pyridoxal and Pyridoxamine Catalysts

Vitamin B₆ serves as universal co‐enzymes in biological systems. However, its catalytic power has not been applied into the area of asymmetric catalysis. Based on the core structure of vitamin B₆, we have developed several types of pyridoxal and pyridoxamine catalysts with different structural skeletons and different electronic properties. With these pyridoxals and pyridoxamines as catalysts, we have realized biomimetic asymmetric transamination of α‐keto acids and biomimetic asymmetric Mannich reaction of glycinate, respectively, to give various chiral α‐amino acids and α,β‐diamino acids in good yields with excellent diastero‐ and/or enantioselectivities. Both of the reactions have perfectly mimicked the corresponding biological transformations.     

P‐Type Photochromism of New Helical Naphthopyrans: Synthesis and Photochemical,Photophysical and Theoretical Study

Two novel helical naphthopyrans have been synthesised. The helical scaffold has the interesting effect of increasing the thermal stability of the transoid‐trans (TT) open isomer formed upon UV irradiation of the closed form (CF), which transforms these naphthopyrans from thermal to photochemical photochromes. The photochromic performance is excellent in both polar and apolar solvents and the conversion percentage from the CF to the TT form can be as high as 92.8 %. We propose a new method to determine the quantum yields of the photochemical processes that lead to transoid‐cis (TC) and TT isomers, and their molar absorption coefficients. The thermal stability of the TT and TC isomers has been studied in different solvents. The quantum yields of fluorescence before and after irradiation, along with the decay lifetimes, have also been measured. TD‐DFT calculations have been performed to determine the relative thermodynamic stability of the species involved in the photochromic mechanism and to rationalise their spectral properties.     

二茂铁-酞菁-富勒烯超分子三元体系的构筑及光物理和电化学性质

采用富勒吡咯烷衍生物中的吡啶或咪唑基与二茂铁修饰的金属酞菁轴向配位构筑了二茂铁-酞菁-富勒烯超分子三元体系, 通过紫外-可见光谱滴定法测定了其配位稳定性(K_assoc约为8.58×10⁴ L/mol). 稳态和时间分辨荧光光谱研究结果表明, 在该超分子三元体系中发生了快速的光诱导电子转移(k_CS约为10⁹ s^-1), 并具有较高的电荷分离态量子产率(Ф_CS=0.88). 循环伏安法数据表明, 其电荷分离驱动力ΔG_CS为负值(-0.60 eV), 说明酞菁和富勒烯之间容易形成电荷分离态.     

基于碘代Bodipy超分子聚合物的构筑和光物理性能研究

本文以对羟基苯甲醛和3-溴丙炔为原料,经过巯基-炔基点击化学反应成功合成了含有双四重氢键的2,6-二碘代-8-[4-(2-脲基-4[1H]-嘧啶酮)苯基]-氟化硼二吡咯甲川化合物(IBodipy-BisUPy),并对其进行了详细的结构表征以及紫外、荧光、瞬态吸收、低温磷光等光物理性质测试。I-Bodipy-BisUPy可通过四重氢键非共价键作用驱动形成超分子聚合物。重原子碘的存在促进了I-Bodipy-BisUPy从单重激发态向三重激发态的系间窜越,可在低温下呈现一个近红外磷光发射峰,其三重态的寿命为56.7μs。利用微乳法将超分子聚合物制备成纳米颗粒,ESR和对1,5-二羟基萘的光敏氧化性能测试表明此超分子聚合物纳米颗粒可在水中产生单重态氧(1O2),且能够实现对底物的光敏氧化。     

Theoretical and Experimental Studies on Photophysical Characteristics of Low Bandgap Polymers

The basic photophysical characteristics of low bandgap polymer poly{2,7＇-9,9-dioctylfluorene-alt-5- diethylhexyl-3,6-bis（5-bromothiophen-2-yl）pyrrolo[3,4-c]pyrrole-1,4-dione}（PDPP-F） have been systematically in- vestigated by means of theoretical and experimental methods. The quantum chemical calculations clarify the molecular structure and electronic transition properties of PDPP-F. The transient absorption data were used to compare the relaxation dynamics of PDPP-F in chlorobenzene and solid film. It is observed that the dynamics process of simulated emission relaxes much faster in comparison with that of excited state absorption in both the solution and solid film. Moreover, the excitation intensity-dependent dynamics of PDPP-F confirms that the interaction among intrachain excitons may occur under photoexcitation in the solution and solid film.     

萘二酰亚胺[3]轮烷的设计合成及发光性能研究

设计合成了以乙氧基柱[5]芳烃为环状分子,萘二酰亚胺衍生物为线性分子的[3]轮烷（[3]R和[3]R'）.其分离产率分别达到45%和62%.利用核磁氢谱和碳谱、二维旋转Overhause波谱（ROESY）以及高分辨质谱等对[3]R和[3]R'的轮烷结构进行了详细表征,并系统研究了轮烷分子的紫外吸收和荧光光谱.由于两侧大体积的乙氧基柱[5]芳烃阻止了[3]轮烷在高浓度下芳香环的过密堆积,使得[3]R和[3]R'即使在固体状态下都可以发射明亮的红色荧光.推测该轮烷分子在发光材料、光电器件等方面有潜在应用,同时本研究也对高效固体发光分子的制备提供了新思路.