排序方式: 共有189条查询结果,搜索用时 93 毫秒
181.
Micha Pieczykolan James B. Derr Amara Chrayteh Beata Koszarna John A. Clark Olena Vakuliuk Denis Jacquemin Valentine I. Vullev Daniel T. Gryko 《Molecules (Basel, Switzerland)》2021,26(16)
Three centrosymmetric diketopyrrolopyrroles possessing either two 2-(2′-methoxyphenyl)benzothiazole or two 2-(2′-methoxyphenyl)benzoxazolo-thiophene scaffolds were synthesized in a straightforward manner, and their photophysical properties were investigated. Their emission was significantly bathochromically shifted as compared with that of simple DPPs reaching 650 nm. Judging from theoretical calculations performed with time-dependent density functional theory, in all three cases the excited state was localized on the DPP core and there was no significant CT character. Consequently, emission was almost independent of solvents’ polarity. DPPs possessing 2,5-thiophene units vicinal to DPP core play a role in electronic transitions, resulting in bathochromically shifted absorption and emission. Interestingly, as judged from transient absorption dynamics, intersystem crossing was responsible for the deactivation of the excited states of DPPs possessing para linkers but not in the case of dye bearing meta linker. 相似文献
182.
Stepanyugin AV Samijlenko SP Martynenko OI Hovorun DM 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2005,61(9):2267-2269
For the first time the ATR technique was applied to obtain IR absorption spectra of DNA and RNA dry films. There was worked out procedure of the nucleic acid removal from germanium plate, which obviously was a main obstacle to application of ATR-IR spectroscopy to nucleic acids. This technique of IR spectroscopy was applied to confirmation of RNA tropism of aurin tricarboxylic acid observed by molecular biological methods. 相似文献
183.
Olena M. Bilash Yuriy T. Zholudov Mykola M. Rozhitskii 《Journal of Solid State Electrochemistry》2011,15(10):2127-2131
The article considers the basic principles of electrochemiluminescent spin traps diagnostic method which consists of efficient
trapping of intermediate labile radical products (free radicals of complex organic molecules) by electrogenerated radical
ions of electrochemiluminescers in different liquid-phase systems including bioobjects. The method permits qualitative and
quantitative identification of such particles by measurement of electrolysis radical recombination luminescence (electrogenerated
chemiluminescence) intensity which is emitted by electrolyzed solutions of organic electrochemiluminescers. The unique possibilities
of the method are illustrated on examples of experimental study of systems with sodium tetraphenylborate and chloride ion. 相似文献
184.
185.
Dr. Jarosław J. Panek Dr. Aneta Jezierska‐Mazzarello Prof. Aleksander Koll Prof. Galina Dovbeshko Dr. Olena Fesenko 《Chemphyschem》2011,12(13):2485-2495
Adsorption of guest molecules on host surfaces can lead to dramatic changes in the spectral properties of the guest. One such effect is surface‐enhanced infrared absorption (SEIRA), observed when the guest is adsorbed on, for example, thin films, metal surfaces, or nanotubes. p‐Nitrobenzoic acid (p‐NBA) exhibits a SEIRA effect when adsorbed on Ag and Au. Herein, the IR spectra of p‐NBA adsorbed on a homemade rough Au surface, recorded in reflection mode with an angle of incidence of 16.5°, are reported. This SEIRA experiment reveals more bands than found by previous SEIRA studies. The intensities of both symmetric and asymmetric COO? and NO2 stretching, in‐plane CH, and C?C ring stretching modes are enhanced. Theoretical models constructed on the basis of density functional theory reveal the binding mode of p‐NBA to gold “particles”. The p‐NBA anion binds to gold much more strongly than the neutral form, and interaction via the carboxylic oxygen atoms is preferred over the nitro group–gold contact. A significant charge transfer during chemisorption is found, which is considered to be crucial in leading to a high SEIRA enhancement factor. 相似文献
186.
Mateusz Mrukiewicz Olena S. Iadlovska Greta Babakhanova Simon Siemianowski Sergij V. Shiyanovskii 《Liquid crystals》2013,40(10):1544-1550
ABSTRACTOblique helicoidal cholesteric liquid crystals (ChOH) offer an unprecedented opportunity to tune selective reflection of light in a broad spectral range from ultraviolet to infrared by an electric field. The major problem is that the temperature range of stable ChOH is typically above the room temperature and is relatively narrow, a few degrees. In this work, we demonstrate that by using a mixture of flexible dimeric and rod-like molecules, one can significantly expand the temperature range of intense Bragg reflection, from 16°C to 27°C. We demonstrate that the selective reflection peak, reflection intensity, bandwidth and threshold electric field are all temperature dependent and discuss the associated mechanisms. The results show that both the electric field and temperature can be used to tune the structural colour of oblique helicoidal cholesteric structures. The proposed material can be used in switchable optical devices based on liquid crystals, such as light modulators, indoor smart windows, and filters. 相似文献
187.
Kohut A Kudina O Dai X Schulz DL Voronov A 《Langmuir : the ACS journal of surfaces and colloids》2011,27(17):10356-10359
Host-guest interactions between cyclohexasilane (Si(6)H(12)) and amphiphilic invertible macromolecules based on PEG and sebacic acid in acetonitrile (neither a solvent for cyclohexasilane nor a support for the micellization of amphiphilic invertible macromolecules) have been investigated. Despite the extended conformation of the macromolecules and the absence of self-assembled polymeric domains, a macromolecular amphiphilicity itself contributes to localizing Si(6)H(12) by AIP and thus enables Lewis acid-base interactions between Si(6)H(12) and the AIP carbonyl groups. The obtained results demonstrate an interesting phenomenon in that insoluble Si(6)H(12) can be localized by AIP macromolecules in a medium that does not support the formation of polymeric domains. 相似文献
188.
Olena VakuliukFrancesco G. Mutti Miguel LaraDaniel T. Gryko Wolfgang Kroutil 《Tetrahedron letters》2011,52(28):3555-3557
The allyl moiety of 4-allyl-anisol was oxidized in the presence of a Fe(III) porphyrin derivative to the corresponding α,β-unsaturated aldehyde in an initial oxidation step with perfect chemoselectivity. Molecular oxygen was employed as the sole environmental innocuous oxidant. The reaction was performed in an aqueous buffer/CH2Cl2 mixture using the detergent Tween 80 to homogenize the system. 相似文献
189.
It has been shown that specific electrostatic interactions between charges of ion dyes and functional groups of polymer play main role in the cause of polar coulored matrices. These interaction prevent by formation tight ion pairs of dyes and their associates. Therefore, such matrices have practically the same electronic spectra as liquid solution of dyes. Electrostatic interactions between dye counterions dominate in low polarity polymer matrices. Process of formation tight ions pair is became easier. Such pairs cause quenching of the fluorescence and distortion of electronic spectra by comparison with liquids. 相似文献