共查询到20条相似文献,搜索用时 15 毫秒
1.
Karl Rechthaler Krystyna Rotkiewicz Andrzej Danel Piotr Tomasik Karen Khatchatryan Gottfried Köhler 《Journal of fluorescence》1997,7(4):301-309
The fluorescence properties of several pyrazoloquinoline derivatives were performed by stationary as well as by time-resolved spectrosopy. Non-donor-substituted compounds show a high quantum yield; transition dipole moments of absorption and fluorescence as well as experimental and calculated lifetimes are in excellent agreement. The donor-substituted compound DMA-DPPQ exhibits a charge transfer fluorescence in polar solvents. Additionally, dual fluorescence appears in polar protic solvents. The nature of the charge transfer state is discussed with respect to the the TICT model. 相似文献
2.
A. Antony Muthu Prabhu S. Siva R. K. Sankaranarayanan N. Rajendiran 《Journal of fluorescence》2010,20(1):43-54
The photophysical behaviour of 2,6-diaminopyridine (DAP) has been studied in solvents of different polarity, pH, β-cyclodextrin
(β-CD) and compared with 2-amino pyridine (2AP). The inclusion complex of both molecules with β-CD are analysed by UV-visible,
fluorimetry, FT-IR, 1H NMR, SEM and AM1 methods. The solvent studies shows i) DAP gives more red shifted absorption and emission maxima than 2AP
molecule and ii) addition of amino group in 2AP effectively increase the resonance interaction in the pyridine ring. A regular
red shift observed in acidic pH solutions suggests intramolecular proton transfer (IPT) present in both molecules. β-CD studies
indicates i) in pH ~ 7, a regular red shifted absorption and emission maxima observed in AP molecules suggests pyridine ring
encapsulated in to the β-CD cavity (1:1 inclusion complex formed) and ii) in pH ~ 1, a blue shifted absorption maxima noticed
in 2AP, is due to protonated amino group deeply encapsulated in to the hydrophobic part of the β-CD cavity. 相似文献
3.
在fullerene-PBTDP-TPA三体体系中的光诱导的分子内电荷转移的实验基础上,分别利用密度泛函理论和含时密度泛函理论以及结合二维、三维实空分析方法对fullerene、PBTDP-TPA二体以及fullerene-PBTDP-TPA三体的基态和激发态的性质进行了理论研究.二维定点表象揭示了激发情况下电子和空穴的相干情况.三维跃迁矩阵展示了跃迁偶极矩的方向和强度,而且三维电荷差密度给出了光诱导的分子内电荷转移的方向和结果.同时,用二维和三维表象的方法对fullerene-PBTDP-TPA三体中光诱导的分子内电荷转移过程进行了验证,揭示了在给予者-桥-接收者三体分子体系中分子内激发时电荷转移的机制.除此之外,还发现直接从给予者到接收者超交换的分子内电荷转移极大地促进了给予者-桥-接收者三体分子体系内的电荷转移. 相似文献
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本文采用含时密度泛函理论研究了用于检测生物硫醇的荧光探针分子的光学性质.通过计算探针分子Mol.1、Mol.2和Mol.3与半胱氨酸和同型半胱氨酸反应前后的单光子吸收和发射性质,研究了碳碳三键和苯环结构对荧光探针性质的影响.随着给电子体三苯胺结构的逐渐完善和碳碳三键的加入,探针分子的振子强度逐渐增大,展现出了更好的荧光探针性质.同时,研究了不同侧枝数目对探针分子性质的影响,结果表明,相较于单枝分子Z1和三枝分子Mol.3,两个侧枝的探针分子Z2振子强度更大,检测效果更佳.增加了碳碳三键和苯环后的单枝新型探针分子Mol.4,相较于具有三枝结构的探针分子Mol.3,具有良好的探针性质,且结构更为简单. 相似文献
6.
S. L. Bondarev V. N. Knyukshto S. A. Tikhomirov I. I. Kalosha D. N. Bobrov N. V. Masalov N. M. Nevar V. I. Tyvorskii A. V. Kel'in O. G. Kulinkovich K. Dziliński 《Journal of Applied Spectroscopy》2002,69(2):230-237
By the methods of luminescence, picosecond spectroscopy, and quantumchemical calculations the mechanisms of electron excitation energy deactivation in some oligothiophenes with intramolecular charge transfer depending on the solvent polarity and viscosity have been investigated. While for 2Npiperidino5(2,2dicyanovinyl)thiophene (PDCVT) the main channel of nonradiative deactivation is the transition to a lower intermediate state with a twisted double bond controlled by the medium viscosity, in the case of (E){2[25piperidino2thienyl]6(trifluoridemethyl)4H4pyranylidene}propanedinitryl (PTFDN) fluorescence quenching is initiated by the solvent polarity. For two other oligothiophenes, 2Npiperidino5cyanothiophene (PCT) and 2Npiperidino5cyanoterthiophene (PCTT), differing in the length of the thiophene chain, we have revealed, along with the effective quenching of fluorescence in shortchain PCT (independent of the solvent polarity and viscosity), an increase in the radiation capacity in PCTT with increasing polarity of the solvent. The possible mechanisms of nonradiative deactivation in the investigated oligothiophenes are discussed. 相似文献
7.
利用(含时)密度泛函理论研究了二甲基胺-二苯甲酮(DMABP)及其氢键二聚物DMABP-MeOH的光物理性质和弛豫动力学过程. 结果表明,在非极性和非质子性溶剂中,DMABP分子的第一和第二激发态跃迁同时具有局域激发和分子内电荷转移的特征;在极性质子性溶剂中,分子间氢键C=O…H-O的形成增加了这两个最低激发态之间的能量差,使DMABP-MeOH的第一激发态具有较强极性的分子内电荷转移特性. 通过计算DMABP和DMABP-MeOH分子的激发态构型弛豫势能曲线研究了激发态动力学弛豫过程. 结果表明,通过扭 相似文献
8.
SUNXu-feng WANGYu JINWei-jun 《光散射学报》2005,17(1):93-94
Under refluxing, carbon nanotube (CNT) and aniline (An) can form the charge transfer complex (CTC) of CNT-An.The corresponding fluorescence emission peaks lied at 564nm and 606nm, respectively, with the excitation wavelength of 516nm in the acetone soluti… 相似文献
9.
Potential models which include charge transfer are used to study ice/water coexistence properties and properties of the ice
Ih phase. Two charge transfer models are used, one which is non-polarizable and one which is polarizable. These models transfer
a discreet amount of charge for each hydrogen bond made and the net charge of a molecule is determined by the difference in
the number of hydrogen bonds a molecule makes as a donor and as an acceptor. In ice Ih, this difference is very near zero
and the net amount of charge transfer is correspondingly essentially zero. This differs from the amount of charge transfer
in the liquid phase. The results for the polarizable charge transfer model confirm other studies that suggest the importance
of polarizability in reproducing the high dielectric constant of ice Ih. 相似文献
10.
在B3LYP/6-311+G(d, p)水平上研究了2-(1H-咪唑)苯硫酚(1d)、2-(噁唑)苯硫酚(2d) 、2-(噻唑)苯硫酚(3d)及其衍生物的基态质子转移过程, 探讨取代基电子效应对质子转移的影响. 结果表明: 吸电子引入后分子平面电子密度减小, N2-H1间距减小, 分子内氢键增强, 醇式到酮式质子转移能垒减小; 供电子基引入后分子平面电子密度增大, N2-H1间距增大, 分子内氢键减弱, 质子转移能垒增大. Localized orbital locator(LOL)分析表明: 取代基的引入对N1原子成键性质产生影响明显. 三者质子转移能垒大小为1d<3d<2d, 取代基引后能垒相对大小不变. 相似文献
11.
在B3LYP/6-311+G(d,p)水平上研究了2-(1H-咪唑)苯硫酚(1d)、2-(噁唑)苯硫酚(2d)、2-(噻唑)苯硫酚(3d)及其衍生物的基态质子转移过程,探讨取代基电子效应对质子转移的影响.结果表明:吸电子引入后分子平面电子密度减小,N2-H1间距减小,分子内氢键增强,醇式到酮式质子转移能垒减小;供电子基引入后分子平面电子密度增大,N2-H1间距增大,分子内氢键减弱,质子转移能垒增大.Localized orbital locator(LOL)分析表明:取代基的引入对N1原子成键性质产生影响明显.三者质子转移能垒大小为1d3d2d,取代基引后能垒相对大小不变. 相似文献
12.
Modulation of intramolecular charge transfer reaction of ethyl ester of N,N-Dimethylaminonaphthyl-(acrylic)-acid (EDMANA)
in anionic sodium dodecyl sulfate (SDS), cationic cetyltrimethylammonium bromide (CTAB) and non-ionic p-tert-octylphenoxy polyoxyethanol (Triton-X 100, TX-100) micelles has been addressed using steady state and time resolved spectroscopy.
The interaction of the CT probe EDMANA with micelles and its location inside the micelles have been investigated by the study
of fluorescence spectral band position of EDMANA in micelle, the effective polarity of micelle-water interface and cetyl pyridinium
chloride induced fluorescence quenching measurement. The effects of urea on the properties of the micelles such as Critical
Micelle Concentration and the interaction between EDMANA and micelles have been explored using EDMANA as emission probe. 相似文献
13.
Numerous studies of donor-acceptor conjugated linear polyenes have been carried out with the goal to understand the exact nature of the excited state electronic structure and dynamics. In this article we discuss our endeavours with regard to the excited state intramolecular charge transfer, photoisomerization and fluorescence probe properties of various donor-acceptor substituted compounds of diphenylpolyene [Ar(CH = CH) n Ar] series and ethenylindoles. 相似文献
14.
A simple colorimetric and ratiometric fluorescent anion sensor 1, was rationally designed and synthesized by facile one-step
condensation on basis of the mechanism of intramolecular charge transfer (ICT). The sensor 1 shows more highly and selectively
ability to F− that induced the color changes from little yellow to purple, absorption-transferred to long wavelength and emission-transferred
to short wavelength. Accordingly, 1H NMR analysis reveals that the F−-induced colorimetric and fluorometric responses of 1 are simply driven by hydrogen bonding interaction between the NH protons
and F− ions. 相似文献
15.
A novel technique for the production of metal electrodes of a nanotransistor with a nanogap less than 4 nm between them is developed on the basis of controlling the electromigration of previously suspended nanowires of the system. A method that allows the embedding of a molecule of Rh(III) terpyridine with aurophilic ligands between electrodes is elaborated, as well. The characteristics of electron transport through a system that consists of the specified molecule with a single-atom charge center indicate the correlated (single-electron) tunneling of electrons. 相似文献
16.
Excited state intramolecular proton transfer (ESIPT) in o-tosylaminobenzaldehyde has been investigated. According to quantum-chemical calculations ESIPT in o-tosylaminobenzaldehyde is barrierless. Product of ESIPT undergoes efficient nonradiative deactivation caused by internal rotation of C(H)OH-group. The solvent orientational relaxation in anionic form of o-tosylaminobenzaldehyde was detected. The mechanism of anionic form fluorescence quenching at the addition of the base in a protic solvent is proposed. It consists in the intermolecular proton transfer from the protonated base to oxygen atom of aldehyde group followed by the internal rotation of C(H)OH-group. 相似文献
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利用飞秒瞬态吸收光谱结合量化计算研究了1-羟基蒽醌在溶剂中的激发态分子内质子转移动力学. 分子受到400 nm光激发后的瞬态吸收谱呈现出激发态吸收和受激辐射两个光谱带. 受激辐射信号较激发态吸收信号滞后出现,由此确定质子转移时间是32 fs. 量化计算表明分子在沿质子转移路径衰变时,分子轨道和能级次序发生了反转,形成锥形交叉. 在质子转移之后,经锥形交叉布居的电子态发生内转换和分子间能量弛豫,时间分别是200 fs和16 ps. 基态回复时间是300 ps. 通过实验和理论研究,证实存在两个质子转移路径,其中主要的衰变路径保持了原来轨道的性质. 相似文献
19.
Polishchuk AV Karaseva ET Emelina TB Cramariuc O Karasev VE 《Journal of fluorescence》2011,21(6):2117-2122
Electronic absorption, luminescence, IR and Raman spectra of polymorphous forms of fluoroquinolones were investigated. Assignment
of the band maxima due to π→π* and n→π* electronic transitions were done. The structural changes are responsible for the absorption
band modifications. One-electron transitions in the long wavelength region, excitation wavelengths, oscillator strengths and
involved molecular orbitals for the zwitter-ionic and cationic protonated forms for different fluoroquinolones were calculated
with quantum-chemical and molecular dynamic methods. The electron density redistributions on the FQs separate fragments during
the photoexcitation to the S1*-state were carry out by Mulliken calculations. It was shown that the degree of neutral and zwitter-ion FQs penetration through
the bacterium membrane is different. 相似文献
20.
E. Radzhabov 《辐射效应与固体损伤》2013,168(1-6):203-207
New emission bands were found in Ce3? doped SrF2 and BaF2 crystals under excitation into the charge transfer region. The bands at 4.85 eV in BaF2 and 4.35 eV SrF2 were found in all crystals with Ce-concentration from 0.001 to 1 mol.%, most prominent in 0.01% samples. Decay of luminescence was simple exponential in BaF2, decay time decreased from 1.3 ms at 65 K to 0.41 μs at 523 K. The decay curve in SrF2 shows t?0.3 dependence at room temperature. All experimental results were naturally explained by assumption that new emission belongs to radiative charge transfer recombination in Ce2?—Fio pairs with different distances between them. 相似文献