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11.
Dr. Mykhaylo Dukh Walter A. Tabaczynski Sairaman Seetharaman Dr. Zhongping Ou Prof. Dr. Karl M. Kadish Prof. Dr. Francis D'Souza Prof. Dr. Ravindra K. Pandey 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(65):14996-15006
A series of chlorin-bacteriochlorin dyads (derived from naturally occurring chlorophyll-a and bacteriochlorophyll-a), covalently connected either through the meso-aryl or β-pyrrole position (position-3) via an ester linkage have been synthesized and characterized as a new class of far-red emitting fluorescence resonance energy transfer (FRET) imaging, and heavy atom-lacking singlet oxygen-producing agents. From systematic absorption, fluorescence, electrochemical, and computational studies, the role of chlorin as an energy donor and bacteriochlorin as an energy acceptor in these wide-band-capturing dyads was established. Efficiency of FRET evaluated from spectral overlap was found to be 95 and 98 % for the meso-linked and β-pyrrole-linked dyads, respectively. Furthermore, evidence for the occurrence of FRET from singlet-excited chlorin to bacteriochlorin was secured from studies involving femtosecond transient absorption studies in toluene. The measured FRET rate constants, kFRET, were in the order of 1011 s−1, suggesting the occurrence of ultrafast energy transfer in these dyads. Nanosecond transient absorption studies confirmed relaxation of the energy transfer product, 1BChl*, to its triplet state, 3Bchl*. The 3Bchl* thus generated was capable of producing singlet oxygen with quantum yields comparable to their monomeric entities. The occurrence of efficient FRET emitting in the far-red region and the ability to produce singlet oxygen make the present series of dyads useful for photonic, imaging and therapy applications. 相似文献
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We report implementations and results of time-dependent density functional calculations (i) of the frequency-dependent magnetic dipole-magnetic dipole polarizability, (ii) of the (observable) translationally invariant linear magnetic response, and (iii) of a linear intensity differential (LID) which includes the dynamic dipole magnetizability. The density functional calculations utilized density fitting. For achieving gauge-origin independence we have employed time-periodic magnetic-field-dependent basis functions as well as the dipole velocity gauge, and have included explicit density-fit related derivatives of the Coulomb potential. We present the results of calculations of static and dynamic magnetic dipole-magnetic dipole polarizabilities for a set of small molecules, the LID for the SF6 molecule, and dispersion curves for M-hexahelicene of the origin invariant linear magnetic response as well as of three dynamic polarizabilities: magnetic dipole-magnetic dipole, electric dipole-electric dipole, and electric dipole-magnetic dipole. We have also performed comparison of the linear magnetic response and magnetic dipole-magnetic dipole polarizability over a wide range of frequencies for H2O and SF6. 相似文献
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Wang J Burdzinski G Kubicki J Platz MS Moss RA Fu X Piotrowiak P Myahkostupov M 《Journal of the American Chemical Society》2006,128(51):16446-16447
Ultrafast photolysis (lambdaex = 270, 350, or 360 nm) of bromophenyl, chlorophenyl, fluorophenyl, and fluoro-para-trifluoromethylphenyl diazirines produces transient species which absorb broadly in the UV and visible regions. Transient decay can be fit to either mono- or biexponential functions (tau1 approximately 0.3-10 ps, tau2 approximately 10-350 ps; dependent on solvent and halogen). Fluoro- and chlorophenylcarbene are formed within the time resolution of the spectrometer (300 fs, 270 nm excitation). Bromophenyl diazirine decay (270 nm excitation) correlates with the growth of bromophenylcarbene. Solvent and substituent effects on the slower decays of the transient absorptions are consistent with assigning the carriers of transient absorption in the visible region to ring-opened zwitterionic species. 相似文献
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We outline an implementation of the origin-independent optical rotation tensor, which includes electric dipole-magnetic dipole and electric dipole-electric quadrupole polarizability. The method is based on approximate time-dependent density functional theory. We utilize time-periodic magnetic-field-dependent basis functions as well as a modified velocity-gauge formulation of dynamic polarizability tensors in order to obtain a gauge-origin independence. To ensure gauge-origin independence of the results within a given numerical accuracy, density fit coefficient derivatives are employed. A damping constant has been introduced into the linear response equations to treat both resonance and nonresonance regions of optical activity. We present calculations for trans-2,3-dimethyloxirane and derivatives thereof as well as calculations for androst-4,17-dien-3-one. In the Appendix, we derive the equivalence between the common-gauge origin and gauge-including atomic orbitals formulations for the optical rotation tensor in time-dependent DFT. 相似文献
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Mykhaylo Tyomkyn 《Journal of statistical physics》2012,148(6):1072-1075
We analyze the abelian sandpile model on ℤ d for the starting configuration of n particles in the origin and 2d−2 particles otherwise. We give a new short proof of the theorem of Fey, Levine and Peres (J. Stat. Phys. 198:143–159, 2010) that the radius of the toppled cluster of this configuration is O(n 1/d ). 相似文献
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Michał Malik Piotr Cmoch Mykhaylo A. Potopnyk Sławomir Jarosz 《Tetrahedron: Asymmetry》2017,28(12):1750-1755
A novel reaction cascade involving a Lewis acid-induced migration of an isopropylidene protecting group followed by the formation of a pyranose or furanose ring and subsequent reduction of the hemiacetal is described. Depending on the reaction conditions, as well as, the stereochemistry of the substrate, polyhydroxylated tetrahydrofurans or tetrahydropyrans can be obtained in reasonable yields. The synthons used in this transformation were prepared via a highly stereoselective one-pot tandem reaction, consisting of a 1,4-Michael addition of vinylmagnesium bromide to d-glucose-derived cyclohexenone followed by aldol reaction with 2,3-O-isopropylidene-d-glyceraldehyde. 相似文献
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Dr. Marta Viciano-Chumillas Dr. Geneviève Blondin Dr. Martin Clémancey Dr. Jurek Krzystek Dr. Mykhaylo Ozerov Prof. Dr. Donatella Armentano Dr. Alexander Schnegg Dr. Thomas Lohmiller Prof. Dr. Joshua Telser Prof. Francesc Lloret Dr. Joan Cano 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(62):14242-14251
A mononuclear iron(III) porphyrin compound exhibiting unexpectedly slow magnetic relaxation, which is a characteristic of single-ion magnet behaviour, is reported. This behaviour originates from the close proximity (≈550 cm−1) of the intermediate-spin S=3/2 excited states to the high-spin S=5/2 ground state. More quantitatively, although the ground state is mostly S=5/2, a spin-admixture model evidences a sizable contribution (≈15 %) of S=3/2 to the ground state, which as a consequence experiences large and positive axial anisotropy (D=+19.2 cm−1). Frequency-domain EPR spectroscopy allowed the mS= |±1/2⟩→|±3/2⟩ transitions to be directly accessed, and thus the very large zero-field splitting in this 3d5 system to be unambiguously measured. Other experimental results including magnetisation, Mössbauer, and field-domain EPR studies are consistent with this model, which is also supported by theoretical calculations. 相似文献
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Tomoyuki Ichiba Ioannis Karatzas Mykhaylo Shkolnikov 《Probability Theory and Related Fields》2013,156(1-2):229-248
We study finite and countably infinite systems of stochastic differential equations, in which the drift and diffusion coefficients of each component (particle) are determined by its rank in the vector of all components of the solution. We show that strong existence and uniqueness hold until the first time three particles collide. Motivated by this result, we improve significantly the existing conditions for the absence of such triple collisions in the case of finite-dimensional systems, and provide the first condition of this type for systems with a countable infinity of particles. 相似文献