排序方式: 共有11条查询结果,搜索用时 359 毫秒
1.
Anna Polishchuk Tatyna Emelina Emilya Karaseva Oana Cramariuc Vladimir Chukharev Vladimir Karasev 《Photochemistry and photobiology》2014,90(1):79-84
The effect of intermolecular proton transfer on the spectral properties of levofloxacin in the ground and excited electronic states was studied. The preferred direction of possible protolytic reactions induced by UV irradiation in this compound was studied. It was found that the proton transfer processes have a considerable effect on the capability of the compound to emit light and occur on the nanosecond timescale. The photochemical reactions of the tree forms of levofloxacin (pH: 4.0, 7.0, 10.0) were studied by laser flash photolysis and product studies. Irradiation at pH 4 yielded a pulse and transient (λmax = 395, 515, 575 nm) assigned to the protonated triplet. Irradiation at pH 7 yielded a transient species (λmax = 525, 610 nm) assigned to the neutral form. Protonation of the anionic singlet excited state was also observed (λmax = 440, 570, 680 nm). 相似文献
2.
Dr. Tomokazu Umeyama Junya Mihara Noriyasu Tezuka Prof. Dr. Yoshihiro Matano Kati Stranius Dr. Vladimir Chukharev Prof. Dr. Nikolai V. Tkachenko Prof. Dr. Helge Lemmetyinen Dr. Kei Noda Prof. Dr. Kazumi Matsushige Prof. Dr. Tetsuya Shishido Dr. Zheng Liu Kaori Hirose‐Takai Prof. Dr. Kazu Suenaga Prof. Dr. Hiroshi Imahori 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(14):4250-4257
Chemically converted graphene (CCG) covalently linked with porphyrins has been prepared by a Suzuki coupling reaction between iodophenyl‐functionalized CCG and porphyrin boronic ester. The covalently linked CCG–porphyrin composite was designed to possess a short, rigid phenylene spacer between the porphyrin and the CCG. The composite material formed stable dispersions in DMF and the structure was characterized by spectroscopic, thermal, and microscopic measurements. In steady‐state photoluminescence spectra, the emission from the porphyrin linked to the CCG was quenched strongly relative to that of the porphyrin reference. Fluorescence lifetime and femtosecond transient absorption measurements of the porphyrin‐linked CCG revealed a short‐lived porphyrin singlet excited state (38 ps) without yielding the porphyrin radical cation, thereby substantiating the occurrence of energy transfer from the porphyrin excited state to the CCG and subsequent rapid decay of the CCG excited state to the ground state. Consistently, the photocurrent action spectrum of a photoelectrochemical device with a SnO2 electrode coated with the porphyrin‐linked CCG exhibited no photocurrent response from the porphyrin absorption. The results obtained here provide deep insight into the interaction between graphenes and π‐conjugated systems in the excited and ground states. 相似文献
3.
A. S. Alekseev A. V. Efimov V. I. Chukharev H. Lemmetyinen 《Bulletin of the Lebedev Physics Institute》2010,37(5):136-140
In the three-layer Langmuir-Schaefer films consisting of a monolayer of donor-acceptor phtalocyanine-fullerene dyad molecules (Bu 3 ProM 2 F) and two layers of poly(3-hexylthiophene) (PHT), placed into an electrochemical cell, the electric current resulted from optical excitation of sampleswas measured with no external voltage source. Samples were excited by the xenon lamp light passed through amonochromator or by a source simulating the solar spectrum. It was shown that the current density in samples reached 40–50 µA/cm2 in the latter case. Current-voltage characteristics of samples were measured. Photovoltaic responses of three-layer structures were studied by the time-resolved Maxwell displacement charge method. The preferred orientation of dyad molecules in the film was demonstrated. 相似文献
4.
Umeyama T Mihara J Tezuka N Matano Y Stranius K Chukharev V Tkachenko NV Lemmetyinen H Noda K Matsushige K Shishido T Liu Z Hirose-Takai K Suenaga K Imahori H 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(14):4250-4257
Chemically converted graphene (CCG) covalently linked with porphyrins has been prepared by a Suzuki coupling reaction between iodophenyl-functionalized CCG and porphyrin boronic ester. The covalently linked CCG-porphyrin composite was designed to possess a short, rigid phenylene spacer between the porphyrin and the CCG. The composite material formed stable dispersions in DMF and the structure was characterized by spectroscopic, thermal, and microscopic measurements. In steady-state photoluminescence spectra, the emission from the porphyrin linked to the CCG was quenched strongly relative to that of the porphyrin reference. Fluorescence lifetime and femtosecond transient absorption measurements of the porphyrin-linked CCG revealed a short-lived porphyrin singlet excited state (38 ps) without yielding the porphyrin radical cation, thereby substantiating the occurrence of energy transfer from the porphyrin excited state to the CCG and subsequent rapid decay of the CCG excited state to the ground state. Consistently, the photocurrent action spectrum of a photoelectrochemical device with a SnO(2) electrode coated with the porphyrin-linked CCG exhibited no photocurrent response from the porphyrin absorption. The results obtained here provide deep insight into the interaction between graphenes and π-conjugated systems in the excited and ground states. 相似文献
5.
A. S. Rokhmin N. V. Nikonorov A. K. Przhevuskii A. V. Chukharev A. M. Ul’yashenko 《Optics and Spectroscopy》2004,96(2):168-174
A partial polarization of luminescence in laser phosphate and silicate erbium-doped glasses was found to take place for the fundamental laser transition 4 I 13/2→4 I 15/2 (λ=1.55 μm) under excitation by linearly polarized laser radiation (532 and 790–990 nm). The shape of the luminescence spectrum depends on the wavelength of the exciting light and on the composition of the glass matrix. The degree of polarization of the luminescence depends on the spectral range of both the excitation and the detection, attaining a maximum of ~1%. The concentration dependence of the degree of polarization is studied. 相似文献
6.
Umeyama T Mihara J Hayashi H Kadota N Chukharev V Tkachenko NV Lemmtyinen H Yoshida K Isoda S Imahori H 《Chemical communications (Cambridge, England)》2011,47(42):11781-11783
Fullerene-encapsulating single-walled carbon nanotubes (C(60)@SWNT) linked with porphyrins by a short bridge have been prepared for the first time. Steady state and time-resolved spectroscopies demonstrated the initial formation of an exciplex state, followed by a charge-separated state. 相似文献
7.
Matano Y Matsumoto K Hayashi H Nakao Y Kumpulainen T Chukharev V Tkachenko NV Lemmetyinen H Shimizu S Kobayashi N Sakamaki D Ito A Tanaka K Imahori H 《Journal of the American Chemical Society》2012,134(3):1825-1839
5-(Diphenylphosphanyl)-10,15,20-triarylporphyrins (meso-phosphanylporphyrins) underwent complexations with palladium(II) and platinum(II) salts to afford phosphapalladacycle- and phosphaplatinacycle-fused coplanar porphyrin dimers, respectively, via regioselective peripheral β-C-H activation of the meso-phosphanylporphyrin ligands. The optical and electrochemical properties of these metal-linked porphyrin dimers as well as their porphyrin monomer/dimer references were investigated by means of steady-state UV-vis absorption/fluorescence spectroscopy, cyclic and differential pulse voltammetry, time-resolved spectroscopy (fluorescence and transient absorption lifetimes and spectra), and magnetic circular dichroism spectroscopy. All the observed data clearly show that the palladium(II) and platinum(II) linkers play crucial roles in the electronic communication between two porphyrin chromophores at the one-electron oxidized state and in the singlet-triplet intersystem-crossing process at the excited state. It has also been revealed that the C-Pt-C linkage makes more significant impacts on these fundamental properties than the C-Pd-C linkage. Furthermore, density functional theory calculations on the metal-linked porphyrin dimers have suggested that the antibonding dπ-pπ orbital interaction between the peripherally attached metal and adjacent pyrrolic β-carbon atoms destabilizes the highest occupied molecular orbitals of the porphyrin π-systems and accounts for the observed unique absorption properties. On the basis of these experimental and theoretical results, it can be concluded that the linear carbon-metal-carbon linkages weakly but definitely perturb the optical, photophysical, and electrochemical properties of the phosphametallacycle-linked coplanar porphyrin dimers. 相似文献
8.
L. M. Voronova M. V. Degtyarev V. F. Chukharev T. I. Chashchukhina V. A. Kazantsev J. G. Krasnoperova 《Bulletin of the Russian Academy of Sciences: Physics》2014,78(10):1001-1006
Changes in the structure and redistribution of alloying elements in 10Kh23N18 austenitic steel after operating at 950°C for 8800 h in contact with La-Sr-Mn-O electrolyte are investigated to establish the reasons for the degrading of the surface layer of a current collector in a solid-oxide fuel cell over long periods of service. It is established that the degradation of the surface layer of steel is associated with the formation of a network of silicon and aluminum oxides along grain boundaries and the considerable discrepancy between the linear thermal expansion coefficients of steel and the solid electrolyte. 相似文献
9.
Chukharev V Vuorinen T Efimov A Tkachenko NV Kimura M Fukuzumi S Imahori H Lemmetyinen H 《Langmuir : the ACS journal of surfaces and colloids》2005,21(14):6385-6391
Two porphyrin-fullerene dyads were synthesized to form self-assembled monolayers (SAMs) on indium-tin oxide (ITO) electrode, with either ITO-porphyrin-fullerene or ITO-fullerene-porphyrin orientations. The dyads contain two linkers for connecting the porphyrin and fullerene moieties and enforcing them essentially to similar geometries of the donor-acceptor pair, and two linkers to ensure the attachment of the dyads to the ITO surface with two desired opposite orientations. The transient photovoltage responses (Maxwell displacement charge) were measured for the dyad films covered by insulating LB films, thus ensuring that the dyads interact only with the ITO electrode. The direction of the electron transfer was from the photoexcited dyad to ITO independent of the dyad orientation. The response amplitude for the ITO-fullerene-porphyrin structure, where the primary intramolecular electron-transfer direction coincides with the direction of the final electron transfer from the dyad to ITO, was 25 times stronger than that for the opposite ITO-porphyrin-fullerene orientation of the dyad. Static photocurrent measurements in a liquid electrochemical cell, however, show only a minor orientation effect, indicating that the photocurrent generation is controlled by the processes at the SAM-liquid interface. 相似文献
10.
Polischuk A. V. Emelina T. B. Cramariuc O. Chukharev V. I. Karaseva T. E. Karasev V. E. 《Russian Journal of General Chemistry》2012,82(2):323-328
The nalidixic acid transient spectra were analyzed and the scheme of photo-conversion of the acid was suggested. At a large
delay of laser pulses the transient absorption spectra contain the bands due to the dissociation of the products of the cation-
and anion-radical photodecomposition in the micro- and millisecond range. By quantum-chemical calculations we revealed that
at the transition to the ion-radical state a proton migration occurs subsequent to the movement of the center of gravity of
the negative charge. The phototransformation of nalidixic was found to proceed with a TICT-effect. 相似文献