共查询到20条相似文献,搜索用时 31 毫秒
1.
N. A. Borisevich S. A. Bagnich T. F. Raichenok V. N. Knyukshto A. V. Baranovskii V. N. Zhabinskii 《Journal of Applied Spectroscopy》2008,75(2):187-191
Biologically active brassinosteroid 24-epicastasterone, ring B of which contains a C=O group and has the nπ*-configuration
for a low-lying electronic excited state, exhibits rapid fluorescence. The wavelengths of the fluorescence maxima of the steroid
dissolved in hexane and acetonitrile are equal to 332 and 394 nm, respectively. The fluorescence lifetime of the steroid dissolved
in acetonitrile is τ = 9.9 nsec. Solutions of 24-epibrassinolide do not luminesce. The long-wavelength electronic absorption
band λmaxabs = 340 nm in the absorption spectrum of an ethanol solution of model compound 2, ring D of which contains a C=O group π*-conjugated with the C=C double bond of ring C, like in the spectrum of the steroid,
has a low extinction coefficient. An ethanol solution of 2 does not fluoresce. 24-Epicastasterone at 77 K in ethanol solution exhibits phosphorescence with λmaxphos = 447 nm. The phosphorescence decay is exponential with τ = 0.79 msec. Compound 2 also phosphoresces. The phosphorescence spectrum of its ethanol solution has a maximum at 490 nm. The phosphorescence decay
is nonexponential in the early stage. The phosphorescence lifetime is 25 msec in the exponential decay region.
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Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 75, No. 2, pp. 182–186, March–April, 2008. 相似文献
2.
We studied the steady-state fluorescence spectra of solutions of FET (4′-(diethylamino)-3-hydroxyflavone) in acetonitrile
that were excited at different temperatures by quanta with different energies located in the range of the main absorption
band and in its long-wavelength wing. We found that, at room temperature, the emission intensity ratio of the bands of the
normal and tautomeric forms, which are located at 505 and 570 nm, respectively, depends on the excitation wavelength. In the
range of the main absorption band 300–360 nm, this ratio remains nearly the same, i.e., 1.45, while, upon excitation in the
range of the long-wavelength wing 360–380 nm of the main band, it decreases to 1.33 at a wavelength of 460 nm. In this same
range, a long-wavelength excitation effect that is unusual for liquid inviscid solvents at room temperature, i.e., a bathochromic
shift of the entire short-wavelength emission band by 11 nm, manifests itself. We propose to explain these dependences using
energy diagrams, which take into account the dependence of free energy on the orientational polarization of the polar solvent.
The observed effect of the long-wavelength shift of the fluorescence spectrum with increasing excitation wavelength is explained
in terms of the inhomogeneous broadening of electronic spectra of polar solutions, and it should be described using the scheme
of energy states that takes into account sublevels of orientational broadening due to orientational dipole-dipole interactions
of the fluorophore with nearest molecules of the polar solvent, as well as the relation between the fluorophore lifetime in
the excited state and the dielectric relaxation time of solvent molecules in the field of the fluorophore dipole. 相似文献
3.
We have obtained and analyzed the absorption, fluorescence, and fluorescence excitation spectra of indole vapor, N-acetyl-L-tryptophan
vapor, and 3-indole aldehyde vapor. From analysis of the dependence of the fluorescence spectrum of the free indole molecules
on the wavelength of the exciting radiation λex, it follows that emission of fluorescence occurs when the molecules undergo a transition from the one electronically excited
state 1Lb. The fluorescence spectra of the studied compounds are insignificantly different, suggesting a major role for the indole
chromophore in formation of the compounds. The absorption spectrum of N-acetyl-L-tryptophan, in which the group of atoms is
added to the indole ring through a-C-C bond, is similar to the spectrum of indole, while the spectrum of 3-indole aldehyde
is significantly different from the indole spectrum due to the effect of the C=O group conjugated with the indole ring. The
fluorescence excitation spectra are considerably different from the absorption spectra. This is associated with the strong
dependence of the quantum yield for the free molecules on λex. Qualitatively, they are mirror-symmetric to the fluorescence spectra of the stodied compounds. Analysis of the data obtained
provides a basis for assuming that in the case of free molecules of indole and its derivatives, the 1La absorption in the extreme long-wavelength region of the spectrum does not overlap 1Lb absorption.
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Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 74, No. 2, pp. 218–222, March–April, 2007. 相似文献
4.
S. M. Arabei D. V. Novik T. A. Pavich K. N. Solov’ev 《Journal of Applied Spectroscopy》2006,73(4):511-521
We have studied the fluorescence and fluorescence excitation spectra at 300 K, 77 K, and 4.2 K for silicate gel matrices colored
with meso-tetrapropylporphin by impregnation of the matrix with a solution of the pigment. Comparison of the data obtained
with the absorption spectra in acidified solutions and analysis of the low-temperature fine-structure vibronic spectra, and
also taking into account data obtained earlier for octaethylporphin in a xerogel showed formation of two cationic forms of
meso-tetrapropylporphin in the gel matrix: the short-wavelength form has a dicationic structure, while the long-wavelength form
has a monocationic structure. We have traced out the correlations of the vibrational structure in the spectra of the dicationic
form with data for the porphin dication, and we have drawn a number of conclusions concerning the normal vibrational modes
that are active in the vibronic fluorescence and absorption spectra of the studied cationic forms. Using the AM1 semiempirical
quantum chemical method, we optimized the geometry of the mesotetrapropylporphin dication: the most stable of the possible
conformers is the dication structure with saddleshaped macrocycle nonplanarity.
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Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 73, No. 4, pp. 453–461, July–August, 2006. 相似文献
5.
N. A. Borisevich I. V. Skornyakov V. A. Khripach G. B. Tolstorozhev V. N. Zhabinskii 《Journal of Applied Spectroscopy》2007,74(5):673-680
We have analyzed the IR spectra obtained for steroidal phytohormones 24-epibrassinolide, 24-epicastasterone, 28-homobrassinolide,
and 28-homocastasterone. The characteristic frequencies of the stretching vibrations of the hydrocarbon groups CH3, CH2, and CH and also the C=O groups in the spectra of brassinolides are higher than in the spectra of castasterones, which makes
it possible to identify them from the IR spectra. Study of the spectra of these brassinosteroids in different media (pressed
samples in KBr, films, solutions in CHCl3 and CDCl3) allowed us to establish the presence of intermolecular interactions in which C=O and OH groups, OH-OH groups participate,
and also the possible formation of intramolecular hydrogen bonds between the OH groups of the molecules.
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Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 74, No. 5, pp. 610–616, September–October, 2007. 相似文献
6.
V. Yu. Plavskii V. A. Mostovnikov G. R. Mostovnikova A. I. Tret’yakova 《Journal of Applied Spectroscopy》2007,74(1):120-132
We have studied the spectral fluorescence and polarization characteristics of Z,Z-bilirubin IXα, at room temperature in chloroform
and in aqueous buffer medium, within an equilibrium complex with human serum albumin (HSA), and also under low temperature
conditions (T = −100°C) in isobutyl alcohol. We have observed a bathochromic shift of the fluorescence spectra, which is most
pronounced for the bilirubin-albumin complex. The following are considered as possible reasons for the observed dependence
of the position of the fluorescence (fluorescence excitation) spectra on the excitation (detection) wavelength: structural
and spectral differences between the chromophores making up the bilirubin molecule; conformational heterogeneity of the pigment
in solution; a contribution to the fluorescence from molecules which have not completed the vibrational relaxation process;
inhomogeneous orientational broadening of the levels; heterogeneity of the microenvironment of the chromophores in the protein
matrix. We show that polarized fluorescence of bilirubin occurs at room temperature, due to the anomalously short fluorescence
lifetime τ (picosecond or subpicosecond ranges). Despite such a short τ, the absorption and emission polarization spectra
suggest the presence of intramolecular nonradiative singlet-singlet energy transfer when bilirubin is excited to high vibrational
sublevels of the S1 state (degree of polarization p = 0.11–0.12). When fluorescence is excited on the long-wavelength slope of the absorption
band, no transfer occurs: the degree of polarization (p = 0.46−0.47) is close to the limiting value (p = 0.50). We discuss
the question of the role played by exciton interactions between chromophores in the bilirubin molecule when it is excited.
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Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 74, No. 1, pp. 108–119, January–February, 2007. 相似文献
7.
V. S. Pavlovich 《Journal of Applied Spectroscopy》2007,74(2):180-187
The effect of dispersion interactions on the electronic spectra of organic compounds is analyzed within second-order perturbation
theory. A formula is obtained which makes is possible to determine the change in the polarizability of the molecules upon
excitation, Δαeg, using data on the effect of the bulk polarizability Pn of the solvent on the position of the electronic spectrum. It is shown that when the solutions are cooled, the long-wavelength
shift of the absorption spectra for the studied anthracenes in alcohols is mainly due to dispersion interactions and is caused
by an increase in Pn. The possibility of using the new formula for Δαeg is demonstrated for anthracenes as an example. It is found that for anthracene, 1-chloroanthracene, 9,10-dichloroanthracene,
9,10-dibromoanthracene, 9,10-diiodoanthracene Δαeg is 16.5, 16.9, 17.2, 18.6, and 20.2 Å3 respectively.
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Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 74, No. 2, pp. 162–168, March–April, 2007. 相似文献
8.
E. S. Voropai M. P. Samtsov K. N. Kaplevskii A. A. Maskevich V. I. Stepuro O. I. Povarova I. M. Kuznetsova K. K. Turoverov A. L. Fink V. N. Uverskii 《Journal of Applied Spectroscopy》2003,70(6):868-874
Comparative analysis of the absorption and fluorescence spectra and fluorescence excitation spectra of thioflavin T (ThT) in various solvents and in the composition of amyloid fibrils has shown that ThT, when excited in the region of the long-wavelength absorption band, fluoresces in the spectral region with a maximum at 478–484 nm. The appearance in aqueous and alcohol solutions of a fluorescence band with a maximum near 440 nm has been attributed to the presence in the composition of the ThT preparations of an impurity with an absorption band in the 340–350-nm range. The literature data showing that in glycerol ThT has a wide fluorescence spectrum with two maxima are due to the artifact connected with the use of a high concentration of the dye. It has been suggested that the cause of the low quantum yield of ThT aqueous and alcohol solutions is the breakage of the system of conjugated bonds due to the reorientation of the benzothiozole and benzaminic rings of ThT in the excited state with respect to one another. The main factor determining the high quantum yield of fluorescence of ThT incorporated in fibrils is the steric restriction of the rotation of the rings about one another under these conditions. The suggestions made have been verified by the quantum-chemical calculation of the ThT molecule geometry in the ground and excited states. 相似文献
9.
T. A. Pavich A. V. Vorobey S. M. Arabei K. N. Solovyov 《Journal of Applied Spectroscopy》2012,79(4):651-655
We have synthesized a folic acid–europium complex conjugate which shows promise for biomedical applications. We have studied the absorption spectra, the luminescence spectra, and the luminescence excitation spectra of folic acid–spacer–amino-substituted phenanthroline and folic acid–spacer–europium chelate conjugates, and also of the individual components of the synthesized triads. All the spectral luminescence data obtained confirm that a folic acid–europium complex conjugate is fogrmed. Binding of the synthesized conjugate to a folate receptor on HeLa tumor cells is demonstrated. 相似文献
10.
V. I. Tomin 《Optics and Spectroscopy》2011,110(4):550-556
The spectral and temporal characteristics of the fluorescence of the anionic form of some 3-hydroxiflavones in different solvents
are studied. This form is observed under selective excitation in the region of the long-wavelength slope of the main absorption
band, and its spectrum consists of a wide structureless band lying between the short- and long-wavelength fluorescence bands
of these molecular probes. The fluorescence excitation spectra of the anionic form differ from the corresponding spectra of
the normal and tautomeric forms. The addition of water to the solution leads to a gradual fluorescence quenching which is
static or belongs to the second kind according to Vavilov’s classification, i.e., occurs in the ground state. 相似文献
11.
V. A. Lapina P. P. Pershukevich A. E. Dontsov M. V. Bel’kov 《Journal of Applied Spectroscopy》2008,75(1):53-63
The spectra and kinetics of fluorescence of two-component solutions of the chlortetracycline (CHTC)-DOPA-melanin (melanin
or ME) system in water have been investigated. The data obtained have been compared to similar data for solutions of CHTC-melanosome
from bull eye (MB), which contains natural melanin, in K-phosphate buffer at pH 7.4. The overall results indicate the occurrence
of complexation between molecules of CHTC and ME as they are being excited. The studies of complexation in the solution of
CHTC-MB in the buffer are complicated by the formation of a CHTC-buffer complex. The effect of optical radiation in the range
330–750 nm on the CHTC-ME complex shows selectivity: the greatest change in the spectrum occurs when the wavelength of the
exciting radiation coincides with the long-wavelength band maximum of the fluorescence excitation spectrum of the CHTC-ME
complex in aqueous solution. In this range, CHTC and especially ME show high photochemical stability. The nature of the radiation
effect on the studied compounds in the hard UV range (λ < 330 nm) differs greatly from that in the range 330–750 nm. It is
apparently accompanied by significant photochemical transmutations of all system components. By comparing the characteristics
of the CHTC-ME systems with those of the related drug doxycycline (DC-ME), the conclusion has been made that the chlorine
atom plays a vital role in formation of the short-wavelength band in the fluorescence spectrum of the CHTC-ME complex.
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Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 75, No. 1, pp. 52–62, January–February, 2008. 相似文献
12.
S. K. Gorbatsevich S. Yu. Mikhnevich O. Yu. Pokotilo 《Journal of Applied Spectroscopy》2000,67(1):45-50
Electronic spectra of three-component solutions are calculated on the basis of a model, which makes it possible to incorporate
the interaction between the molecules of a polar solvent, including the case of dielectric saturation. It is shown that the
use of the theory of three-component solutions, which disregards the interaction between the molecules of a polar solvent,
can lead to an overestimation of the efficiency with which an activator interacts with the molecules of a polar solvent.
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 67, No. 1, pp. 38–41, January–February, 2000. 相似文献
13.
Absorption and luminescence spectra of a 4-nitro-4-dimethylaminobutadiene molecule in binary solvents have been experimentally
obtained and investigated. Formation of the absorption spectra is associated with a chromophore grouping of the molecule in
a bent state, while the bathochromic shift of the band in the absorption spectrum is consistent with the theory of dipole-dipole
interaction of a bipolar molecule with solvent molecules. The fluorescence spectrum and its form and bathochromic shift depend
not only on the solvent polarity but also on the proportion and kind of binary mixture of solvents. For a certain proportion
of the binary solvent, radiation has been generated at λ=610 nm in pumping by a nitrogen laser.
Reported at the International Conference on Luminescence, November, 22–24, 1994, Moscow.
Belarusian State University, 4, F. Skorina Ave., Minsk, 220080, Belarus. Translated from Zhurnal Prikladnoi Spektroskopii,
Vol. 64, No. 1, pp. 119–121, January–February, 1997. 相似文献
14.
E. Birckner U.-W. Grummt H. Rost A. Hartmann S. Pfeiffer H. Tillmann H.-H. Hörhold 《Journal of fluorescence》1998,8(1):73-80
The absorption and fluorescence of substituted distyrylbenzene (DSB) derivatives and segmented poly(phenylene vinylene) (PPV)
derivatives are characterized by long-wavelength absorption maxima and absorption coefficients of λa = 380–450 nm, ε = 20,000–60,000 M−1 cm1 and fluorescence maxima, quantum yields, and decay times of λr = 440–530 nm, Φf = 0.2–0.9, and Τ = 0.8–2.5 ns, respectively. Alkoxy substituents at the central phenylene ring of DSB groups increase the
bathochromic shift in the spectra in comparison to DSB, without a significant decrease in the high DSB fluorescence quantum
yield. Both phenyl and cyano substitutions at the vinylene bridge lead to a further bathochromic shift of the fluorescence
and a decrease in the quantum yield to ca. 0.4. The DSB derivatives and the related segmented PPV derivatives show nearly
the same absorption spectra, fluorescence spectra, and radiative rate constantsk
f= Φf/Τ, indicating the efficacy of the segmentation of the polymer chain. The radiative rate constants determined by the Φf and Τ values and by the Strickler/Berg formula are in reasonable agreement. This supports the possibility of interpreting
the properties of the polymers in terms of their DSB units. The decrease in the emission anisotropy can be ascribed to multistep
energy transfer processes between different oriented segments. 相似文献
15.
Spectral-luminescent properties and photoinduced transformations of bisanthene and bisanthenequinone
Based on the study of photochemical transformations of bisanthene in oxygen-containing solutions, it was established that
the final product of this reaction is bisanthenequinone. It is shown that in the course of this oxidation reaction the intermediate
compounds endomonoperoxide and bisanthene endobiperoxide are formed. Quantum-chemical calculation of the geometrical structure
and electronic spectra of the endoperoxides has shown that they have a nonplanar structure, and their absorption spectra experience
a large hypsochromic shift. The absorption and fluorescence spectra of solutions of bisanthene in different solvents at 300
and 77 K were investigated. The large Stokes shift of the fluorescence spectra of the solutions of bisanthene in benzene and
in its methyl derivatives is explained by the action of intermolecular interactions. The quasi-line fluorescence spectra of
solutions of bisanthene in the matrices of saturated hydrocarbons were recorded.
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 67, No. 2, pp. 176–182, March–April, 2000. 相似文献
16.
N. G. Bakhshiev S. K. Gularyan G. E. Dobretsov A. Yu. Kirillova V. Yu. Svetlichnyĭ 《Optics and Spectroscopy》2008,104(5):732-736
It is proposed to use the method of selective fluorescence excitation to find absorption spectra (fluorescence excitation spectra) of 1 : 1 primary solvated complexes between polar molecules of an organic dye and the active component of a binary solvent, whose neutral component is a nonpolar or low-polarity liquid. The technique was tested with diluted solutions of 4-dimethylaminochalcone (4-DMC) in mixtures of ethylbenzene with dimethyl formamide at extremely low contents of the latter. It is shown that the experimental absolute shift of the long-wavelength vibronic absorption band of three-component DMC solutions is in a good quantitative agreement with the analogous shift obtained independently based on the semi-empirical theory describing the joint effect of nonlinear (complexation) and linear (solvation) dipole-dipole interactions on the shift of spectral bands. 相似文献
17.
Solvent effects on 2,3-bis(chloromethyl)-1,4-anthraquinone (DCMAQ) and the molecular recognition of DCMAQ in calix[8]arene were investigated using optical absorption and fluorescence emission techniques. Optical absorption spectra show n→π* band in 350–500 nm region. It also indicates that the dipole–dipole interaction and solvent reorganization energies are responsible for the observed features in different solvents. The observed quantum yield of DCMAQ in different solvents is due to the formation of intermolecular hydrogen bond and reorientation of solvent molecule in the excited state of DCMAQ. Excited state dipole moment of DCMAQ is calculated by solvatochromic data and it shows a higher excited state dipole moment than ground state dipole moment. Optical absorption and fluorescence studies of DCMAQ in calix[8]arene elucidate the evidence for the formation of complex between DCMAQ and calix[8]arene. The inclusion ratios and inclusion constant of the host–guest complexes are also determined. 相似文献
18.
S. F. Shkirman K. N. Solov’ev T. F. Kachura S. A. Arabei E. D. Skakovskii 《Journal of Applied Spectroscopy》1999,66(1):68-75
Low-temperature (77 K) absorption, fluorescence, and fluorescence-excitation spectra and the fluorescence polarization spectrum
for N-methyl-meso-tetraphenylporphin (N-methyl-TPP) are measured. Based on the polarization spectrum the absorption spectrum
in the visible region (a “generic” porphyrin spectrum) is interpreted. In particular, it is shown that the fifth absorption
band (the “Longo band”) that manifests itself in some porphyrins is a Qy(0–2) band and does not belong to the individual electron transition. Emphasis is placed on the region of the Soret band.
It is inferred that at least two allowed electron transitions (G →Bx and G→By) polarized mutually perpendicularly manifect themselves in this region. The interpretation of the Soret band of porphyrins
[2] that attributes this band to one electron transition G→Bx is thereby rejected. This interpretation is confirmed by computer modeling of the polarization spectrum. Special features
of the experimental polarization spectrum are explained by a more developed vibrational structure and, possibly, a larger
half-width of the Bx band than the half-width of the By band. The contribution of the states of intramolecular charge transfer to the formation of the Soret band is discussed.
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 66, No. 1, pp. 65–72, January–February, 1999. 相似文献
19.
Synthesis and spectral-luminescence properties of the conjugate of 24-epibrassinolide with porphyrin
T.?F.?Raichyonok V.?A.?Khripach V.?N.?Zhabinskii O.?V.?Konstantinova P.?B.?Dra?ar D.?Monti 《Journal of Applied Spectroscopy》2009,76(4):542-546
The synthesis of a previously unknown conjugate of 24-epibrassinolide with porphyrin is described. Four molecules of 24-epibrassinolide
are bonded to a molecule of porphyrin by selective formation of cyclical boric ethers in diol groups of the side chain. Electronic
spectra of the synthesized conjugate of 24-epibrassinolide with porphyrin are measured and analyzed. The spectral and luminescence
characteristics of the initial porphyrin and the conjugate are found to be similar. The quantum yield and fluorescence lifetime
of the conjugate in tetrahydrofuran are 0.06 and 10.6 ns, respectively. The extinction coefficient of the conjugate in tetrahydrofuran
is 385,000 (M∙cm)–1 at a wavelength of 418 nm. 相似文献
20.
A. N. Murashkevich A. S. Lavitskaya T. I. Barannikova I. M. Zharskii 《Journal of Applied Spectroscopy》2008,75(5):730-734
The composites xTiO2-(1−x)SiO2 (x = 0.1, 0.5, 0.9) were obtained by coprecipitation from solutions of alkoxides: tetraethoxysilane (TEOS) and titanium tetraisopropoxide
(TIPT). Intermolecular interaction of the components of the composite is apparent in the IR absorption spectra in the 928–952
cm−1 region, and is connected with bending vibrations of the Si-O-Ti bond.
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 75, No. 5, pp. 724–728, September–October, 2008. 相似文献