四-α(β)-(4-吡啶氧基)酞菁锌的光物理性质研究

测定了新合成的α位取代和β位取代的四-(4-吡啶氧基)酞菁锌配合物的UV-Vis吸收光谱、荧光光谱及激发单重态寿命、纳秒瞬态吸收光谱与激发三重态寿命.在此基础上,与相关配合物进行了比较,探讨了取代基及其取代位置对酞菁锌配合物的吸收光谱、激发单重态寿命及激发三重态寿命的影响.     

锌卟啉轴向配合物的光谱特性及配位二聚体分子内的能量传递

通过轴向配位作用构造了ZnTPP-H₂(m-py)TPP卟啉二元体系,研究了配位二聚体的可见吸收光谱和荧光发射光谱特性,考察了二聚体分子内的能量传递过程,观察到能量从激发态ZnTPP^*流向H₂(m-py)TPP。作为对比,研究了ZnTPP-py体系的可见吸收光谱和荧光发射光谱。轴向配位的吡啶引起了ZnTPP荧光光谱明显红移,没有分子内的能量转移过程发生。用吸收光谱和荧光光谱方法计算了加合反应的平衡常数,得到了基本一致的结果。     

PhotochemCAD 2: a refined program with accompanying spectral databases for photochemical calculations

The PhotochemCAD program has been revised extensively. Calculations can be performed using eight modules (oscillator strength, transition dipole moment and natural radiative lifetime, Förster energy transfer, multicomponent analysis, blackbody radiator, artificial spectrum creation, transmission calculation, and analysis of energy transfer among linear multichromophore arrays). The user interface has been streamlined to facilitate visual display, operation of the various modules, input of user data via a wizard and output of spectra and calculations. The database of absorption and fluorescence spectra has been expanded to 150 photochemically relevant compounds. A database of solar spectra has been added. The program runs under Windows and is equipped with extensive literature references and help features, including a tutorial section with video files.     

铜(Ⅱ)离子与神经红蛋白的相互作用

利用紫外可见吸收光谱、荧光光谱、同步荧光光谱及圆二色(CD)光谱研究了铜髤离子与神经红蛋白(NGB)的相互作用。结果表明,Cu2+离子使NGB在280nm处的紫外吸收增强,说明Cu2+与NGB发生了相互作用;Cu2+使NGB内源性荧光发生猝灭,其猝灭机制为静态猝灭;同步荧光光谱表明,Cu2+使色氨酸微环境的疏水性有所降低,Cu2+对NGB的作用位点更接近于色氨酸;CD光谱显示Cu2+没有引起NGB二级结构明显的变化。     

Cyclic imides. XII(i). Absorption and fluorescence spectra of 3-benzamidophthalimides

The ultraviolet absorption, fluorescence, and infrared absorption spectra of fifteen 3-benz-amidophthalimides are described. In general, the nature or position of the substituents on the benzamide moiety has little effect on the ultraviolet absorption and fluorescence spectra of these, compounds. The absorption baud at 271 nm is more sensitive to substituent variations than the other two bands (at 227 nm and 341 nm), indicating this band is a composite of bands observed in the spectra of 3-aminophthalimide and the substituted benzamide. The fluorescence of 3-amino-phthalirnide and the 3-benzamidophthalimides is due to the same transitions. The infrared absorption wavenumbers for the amide and imide vibrations of the 3-benzamidophthalimides are characterized.     

UV-vis, IR and 1H NMR spectroscopic studies of some 6-chloro,2-pyridyl hydrazones

The electronic absorption spectra of some 6-chloro,2-pyridyl hydrazones are studied in seven organic solvents of different polarity. The absorption bands are assigned to the corresponding electronic transitions and the effect of solvent parameters on the charge transfer energy (E(CT)) is investigated. The spectra in buffer solutions of varied pH are also studied and utilized for the determination of the acid dissociation constants of the compounds under study. The fluorescence spectra were recorded for one of the studied compounds in six solvents, the solvent effect on the photoquantum yield and spectral pattern are also studied. Bands of diagnostic importance in the IR spectra and signals in the (1)H NMR spectra are assigned. The results of the present investigation are supported by some MO calculations using the atom super position and electron delocalization molecular orbital theory (ASED-MO) and Gaussian 94 program. The geometry is optimized using the PM3 method.     

Absorption and emission spectroscopic characterisation of 8-amino-riboflavin

The flavin dye 8-amino-8-demethyl-d-riboflavin (AF) in the solvents water, DMSO, methanol, and chloroform/DMSO was studied by absorption and fluorescence spectroscopy. The first absorption band is red-shifted compared to riboflavin, and blue-shifted compared to roseoflavin (8-dimethylamino-8-demethyl-D-riboflavin). The fluorescence quantum yield of AF in the studied solvents varies between 20% and 50%. The fluorescence lifetimes were found to be in the 2–5 ns range. AF is well soluble in DMSO, weakly soluble in water and methanol, and practically insoluble in chloroform. The limited solubility causes AF aggregation, which was seen in differences between measured absorption spectra and fluorescence excitation spectra. Light scattering in the dye absorption region is discussed and approximate absorption cross-section spectra are determined from the combined measurement of transmission and fluorescence excitation spectra. The photo-stability of AF was studied by prolonged light exposure. The photo-degradation routes of AF are discussed.     

Absorption and Fluorescence Spectral Database of Chlorophylls and Analogues

Absorption spectra and fluorescence spectra are essential for use across the photosciences, yet such spectra along with the all‐important values for molar absorption coefficient (ε) and fluorescence quantum yield (Φ_f) often are found with great difficulty. Here, a literature survey concerning the vital class of chlorophyll compounds has led to identification of spectra for 150 members. Spectra in print form have been digitized (with baseline corrections) and assembled into a database along with literature references, solvent identity and values for ε and Φ_f (where available). The database encompasses photosynthetic tetrapyrroles wherein the chromophore is a porphyrin (e.g. chlorophyll c₁, protochlorophyll a), chlorin (e.g. chlorophyll a, bacteriochlorophyll c) or bacteriochlorin (e.g. bacteriochlorophyll a). Altogether, the database contains 305 absorption spectra (from 19 porphyrins, 109 chlorins and 22 bacteriochlorins) and 72 fluorescence spectra (from 10 porphyrins, 30 chlorins and 4 bacteriochlorins). The spectral database should facilitate comparisons and quantitative calculations. All spectra are available in print form in the Supporting Information. The entire database in digital form is available with the PhotochemCAD program for free downloading and further use at http://www.photochemcad.com .     

Spectral-luminescence characteristics of 1,3-diaryl-4,7-phenanthrolines

The effect of the nature of the substituents and the solvent on the absorption and fluorescence spectra and the fluorescence quantum yields of 1,3-diaryl-4,7-phenanthrolines was studied. Electron-donor groups in the para position of the phenyl ring cause a bathochromic shift of the absorption and fluorescence spectra and an increase in the fluorescence quantum yields. A change in the polarity of the solvent leads to a significant shift of the fluorescence spectra of hydroxy and dialkylamino derivatives of 4,7-phenanthroline.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1651–1654, December, 1987.     

Synthesis and peripheral substituent effects of bay-annulated indigo derivatives

In this study, indolo-naphthyridine-6,13-diones (5a–d) with four different peripheral substituents were prepared via bay-annulation reactions of indigo. The resulting compounds (5a–d) exhibited fluorescence in the red to near-IR region, while the parent indigo molecule showed no fluorescence. Although the peripheral substituents were oriented to the exterior of the π-conjugated system, the electronic structure affected the absorption and fluorescence spectra. Moreover, calculated molecular orbitals and absorption spectra successfully reproduced the experimental absorption spectra and cyclic voltammograms.     

A Spectroscopic Study of the Effects of Various Solvents and Sol-Gel Hosts on the Chemical and Photochemical Properties of Thionin and Nile Blue A

Tetraethyl orthosilicate (TEOS)-based gels were doped with two optically active organic indicators, thionin and nile blue A. Before trapping in a sol-gel host, thionin and nile blue A were both evaluated for solvent and protonation effects on their spectral properties. Only extreme pH values provided by HCl, NaOH, and NH₄OH produced new absorption and/or fluorescence bands. Introduction of nile blue A into alkaline environments (0.1N NaOH, NH₄OH) results in the appearance of a broad absorption band centered near 520 nm whereas highly acidic environments (1N HCl) show a reduction of the 635 nm absorption peak accompanied by an absorption band located near 460 nm. A marked decrease is observed in the optical density of thionin in 1N HCl solution which results in a reduction in the fluorescence intensity. The absorption and fluorescence spectra also reveal a decrease in a pH 11 solution of NH₄OH as compared to neutral conditions. Both dyes formed dimers when the sol-gel host, initially synthesized with TEOS, was organically modified with methyltrimethoxysilane (MTMS). However, thionin dimers were present in all silica-based sol-gel compositions, as evidenced by the absorption and fluorescence spectra. Substitution of MTMS for some of the TEOS in the gel matrix resulted in blue shifts in the absorption and fluorescence spectra of nile blue A. The absorption peak shifted 50 nm to 596 nm whereas the fluorescence shifted around 40 nm to 635 nm. These blue shifts resulted from the reduced polarity of the silica-based xerogel. Thionin also exhibited shifts in its absorption and fluorescence spectra with organic modification by MTMS. The absorption shifted approximately 3 nm to 595 nm while the fluorescence maximum decreased 7 nm to 630 nm. The blue shifts in the spectra of thionin with additions of MTMS were attributed to surface sites that altered the molecular structure of the adsorbed thionin molecules.     

Solvent Effects on Spectral Property and Dipole Moment of the Lowest Excited State of Coumarin 343 Dye

Steady-state absorption and fluorescence spectra, and time-resolved fluorescence spectra of coumarin 343 (C343) were measured in different solvents. The effect of the solvent on the spectral properties and dipole moment of the lowest excited state of C343 were investigated. It was found that the absorption and fluorescence spectra red-shifted slightly and strongly with increasing solvent polarity, respectively, because the charge distribution of the excited state leaded to the increasing difference between the absorption and fluorescence spectra with increasing solvent polarity. The dipole moment of the lowest excited state of C343was determined from solvatochromic measurements and the quantum chemical calculation, and the results obtained from these two methods were fully consistent. Investigations of the time-resolved fluorescence of C343 in different solvents indicated that the fluorescence lifetimes increased nearly linearly with increasing solvent polarity from 3.09 ns in toluene to 4.45 ns in water. This can be ascribed to the intermolecular hydrogen bonding interactions between C343 and hydrogen donating solvents.     

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.     

The fluorescence spectrum of HCN (A≈1 A′' → X≈1 Σ+) using ArF laser excitation

The fluorescence spectrum of HCN A≈(¹A′') → X≈(¹Σ⁺) is reported using a tuned ArF laser as the excitation source. Assignments for the fluorescence spectra from two upper state vibrational levels are given. Franck—Condon factors for the absorption and fluorescence spectra are calculated. A laser-induced fluorescence spectrum is given which agrees with published absorption spectra of HCN.     

Dimers of polar chromophores in solution: role of excitonic interactions in one- and two-photon absorption properties

The possibility to exploit a bottom-up approach to design and synthesize multichromophoric structures from a single molecular unit is strategic for the targeted synthesis of molecular compounds with well defined linear and nonlinear absorption properties. In this view, it is important to be able to predict the properties of multichromophoric units, based on the knowledge of the properties of the individual chromophores and their mutual arrangement. To this end, we present a combined experimental and theoretical study on 4-(para-di-n-butylaminostyryl)-pyridine, a push-pull molecule, and its dimer, 4,4'-bis(para-di-n-butylaminostyryl)-2,2'-bipyridine, formed by connecting the two pyridine groups into a bipyridine structure. One photon absorption and fluorescence spectra are measured in solvents of different polarity, and two-photon absorption spectra are recorded in dichloromethane. Experimental results are compared with results of TDDFT (Time-Dependent Density Functional Theory) and CIS (Configuration Interaction with Single excitation) methods implemented in the Gaussian03 program suite. An essential-state analysis of optical spectra is used to rationalize the observed behavior.     

Formation and dissociation of rhodamine 800 dimers in water: steady-state and ultrafast spectroscopic study

We investigated the fundamental photophysics and photochemistry of a cationic dye rhodamine 800 (R800) in water using steady-state and ultrafast time-resolved spectroscopies. In the ground state, the monomer and dimer coexist in equilibrium, which causes significant concentration dependence of UV-visible (vis) absorption spectra. We determined the equilibrium constant as well as the molar absorption spectra of the monomer and dimer from a global fitting analysis of the UV-vis spectra. The obtained pure dimer spectrum indicates that it is a nonparallel H-dimer. In contrast to the absorption spectra, the steady-state fluorescence spectra do not show any noticeable concentration dependence. The fluorescence lifetime was determined as 0.73 ns regardless of the concentration, and the fluorescence of R800 in water was solely attributed to the monomer. In femtosecond time-resolved absorption measurements, we observed the S(n) <-- S1 absorption bands of the monomer and the dimer, as well as the ground-state bleaching signals. It was found that the S1 dimer dissociates to produce the S1 monomer (and the S0 monomer) or relaxes to the S0 dimer with a time constant of as short as 3.0 ps, which brings about the absence of dimer fluorescence.     

Fluorescent properties of cationic-anionic polymethine dyes

The fluorescence spectra were studied and the quantum yields of the fluorescence of a number of cationic-anionic polymethine dyes were measured in polar, low-polarity, and nonpolar solvents. It was shown that the fluorescence spectra of cationic-anionic dyes in polar solvents, like the absorption spectra, represent the sum of the fluorescence spectra of the corresponding cationic and anionic dyes. For dyes in which the absorption bands of the anion and cation are close and a new short-wave band arises in the ion pairs, excitation into this band virtually does not lead to fluorescence, which is a consequence of the forbidden nature of the long-wave transition that arises as a result of the interaction of the chromophores. For a number of cationic-anionic dyes in ion pairs an energy transfer is observed: When an ion possessing short-wave absorption is excited, an ion with long-wave absorption fluoresces.N. N. Semenov Institute of Chemical Physics, Russian Academy of Sciences, 117977 Moscow. Translated fromIzvestiya Akademii Nauk, Seriya Khimicheskaya, No. 11, pp. 2532–2539, November, 1992.     

Vibronic Structures in Absorption and Fluorescence Spectra of Firefly Oxyluciferin in Aqueous Solutions

To elucidate the factors determining the spectral shapes and widths of the absorption and fluorescence spectra for keto and enol oxyluciferin and their conjugate bases in aqueous solutions, the intensities of vibronic transitions between their ground and first electronic excited states were calculated for the first time via estimation of the vibrational Franck–Condon factors. The major normal modes, overtones and combination tones in absorption and fluorescence spectra are similar for all species. The theoretical full widths at half maximum of absorption spectra are 0.4–0.7 eV and those for the fluorescence spectra are 0.4–0.5 eV, except for phenolate‐keto that exhibits exceptionally sharp peak widths due to the dominance of the 0–0′ or 0′–0 band. These spectral shapes and widths explain many relevant features of the experimentally observed spectra.     

Yb∶YAB晶体的生长及性质

研究了ＹｂｘＹ１－ｘＡｌ３（ＢＯ３）４（Ｙｂ∶ＹＡＢ）晶体的生长及光学性质,结果表明,以Ｋ２Ｍｏ３Ｏ１０作为助熔剂生长Ｙｂ∶ＹＡＢ晶体效果较好,根据测定的Ｙｂ∶ＹＡＢ折射率计算的一类位相匹配角为θｍ（Ⅰ）＝３４°１２′,与实验测定值θｍ（Ⅰ）＝３４°３８′吻合较好。该晶体室温吸收谱在９５６和９７５ｎｍ处存在两个吸收带,适于ＩｎＧａＡｓ泵浦;室温π偏振吸收比σ偏振吸收略强;１０３和１０４μｍ处各存在一荧光峰,１０３μｍ处荧光寿命为１３７９ｍｓ;估算的发射截面数量级为１０－２１ｃｍ２     

A STUDY ON THE SPECTRUM CHARACTER AND PHOTOSTABILIZATION ABILITY OF A NOVEL UV-ABSORBER-DIBENZOYL METHANE

The absorption and fluorescence spectra of dibenzoyl methane have been studied. From the absorption spectra it was found that there are two peaks locating at 252 nm and 340 nm, respectively, similar to that of o-hydroxy benzophenone which can form intra-molecular hydrogen bond. Besides, an uncommonly large Stoke's shift of fluorescence can be observed in fluorescence spectra. The photostabilizing effects of dibenzoyl methane and UV-531 on the photodegradation of poly (cis-1, 4-butadiene) in solution have been investigated and compared. A possible mechanism was discussed.