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Showing 1 to 20 of 34 for “"photoisomerization"”.
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Nonadiabatic Dynamics of Cis-Trans Photoisomerization --- a First Principles Study
Cis-trans photoisomerization is a chemical reaction which converts light to mechanical energy on a molecular scale. Unique methods which provide an accurate theoretical description of these reactions are presented here. An implementation of the ab initio multiple spawning (AIMS) dynamics algorithm …
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Excited State Dynamics of Trans-Cis Photoisomerization in Photoactive Yellow Protein Chromophores
As an efficient and accurate quantum chemical method for photobiological and condensed phase applications, pseudospectral time-dependent density functional theory (PS-TDDFT) is presented, which alleviates the O(N4) scaling problem in two-electron integral calculations. For the test cases in this …
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First Principles Dynamics and Coarse-Grained Characterization of Photoisomerization in Complex Environments
These reactions occur on ultrafast timescales, to which traditional transition state theories (TSTs) do not necessarily apply. To quantify the rates of such non-TST reactions, we have applied non-linear dimensionality reduction techniques to dynamical simulation data. Such techniques permit …
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First Principles Studies of Cis-Trans Photoisomerization Dynamics and Excited States in Ethylene, Stilbene, Azobenzene and TATB
In principle, the energy required for electronic excitation may also arise from collisions with one or more nearby molecules. One might suggest an importance of electronic excitation in chemical processes at high temperatures and pressures, such as detonation. This possibility was tested in solid …
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THE PHOTOISOMERIZATION OF 2-PHENYL-3H-INDOL-3-ONE N-OXIDE (2- PHENYLISATOGEN) TO 2-PHENYL-4H-3,1-BENZOXAZIN-4-ONE
The use of nitrones is an important synthetic tool for the organic chemist. An unusual reaction of these nitrones is a photochemical ring expansion under proper conditions that allows the nitrone oxygen to migrate past a carbon atom in a ring and insert itself into a ring that is expanded by the …
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Modeling Dark- and Light-Induced Crystal Structures and Single-Crystal Optical Absorption Spectra of Ruthenium-Based Complexes that Undergo SO2-Linkage Photoisomerization
… state. This striking effect is caused by photoisomerization of metastable photoinduced states, which are metastable if kept at suitably low temperatures. This illustrates the possibility of these materials to operate as nanotechnological devices themselves, with the potential for optical …
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Predicting Kinetics of Spin-Dependent Reactions in an External Magnetic Field with Nonadiabatic Statistical Theory
… coupling constant and isotropic g-value upon photoisomerization. Therefore, control of spin states of this copper(II) complex can be achieved through the photoisomerization of the spirooxazine ligand.
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Two-Photon Microscopy of E-Combretastatin uptake and activation in live mammalian cells
… cytotoxic.Combretastatins undergo reversible photoisomerization upon irradiation with UV/visiblelight. Here a novel form of two-photon phototherapy is proposed, in which the "inactive"fnms(£)-combretastatins are used as anticancer pro-drugs that may be activated (converted tothe cw-isomer) by …
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Stereo-directing effect of molecularly imprinted polymers on cinnamic acids
… of cis and trans isomers resulting from photoisomerization. The work represents a novel approach to stereoselective synthesis and purification. MIPs were synthesized via precipitation polymerization using t-4MCA as the template, methacrylic acid (MAA) as the functional monomer, and …
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Quantum chemistry and surface hopping dynamics of azobenzenes
… surface hopping is applied to model the photoisomerization of azobenzene dimers, (i) for the isolated case (exhibiting the exciton coupling between two molecules) as well as (ii) for the constrained case (providing the van der Waals interaction with environment in addition to the exciton …
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Interfacial bioorthogonal chemistry for biomaterials synthesis and patterning and development of catalytic method for "turning-on" the tetrazine ligation
… synthesis. Based on the previous art of photoisomerization methods in Fox group, I carried out the first practical photosynthesis of trans-cycloheptene derivatives that were stabilized as silver(I) complexes form, as well as the photoisomerization of silicon-containing …
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Molecular Dynamics and Quantum Chemistry Studies of the Protein Bacteriorhodopsin
… syn → all-trans,15-anti ""bicycle peddle"" photoisomerization. Electronic excitations and conformational potential surfaces of retinal in vacuo and in bacteriorhodopsin are determined by means of the ab initio CASSCF method. The calculations account for the protein environment by explicitly …
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Molecular dynamics studies of membranes and membrane proteins
… integral membrane protein bacteriorhodopsin: The photoisomerization and subsequent thermal reactions of the protein were studied by molecular dynamics simulations. Internal water molecules were placed in the protein. The studies attribute a key role to the Schiff base-counterion electrostatic …
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Controlling molecules with lasers and lasers with molecules
… molecular states, and most recently, control photoisomerization in proteins [1, 2, 3]. In this thesis I began by seeking to apply this technique to manipulate spin. In our early work we pursued polarizing electron spins and nuclear spins for NMR Quantum Computation. We studied the electron …
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Studying the Structural Dynamics and Aptamer-Ligand Interactions in the Cocaine-Binding Aptamer through Fluorescence Spectroscopy
… and thermal stability analyses. Furthermore, photoisomerization of stilbene coupled with ligand-induced binding mechanism of the cocaine-binding aptamer were employed for the development of the Photochrome Aptamer Switch Assay. This research aims to gain insight into how aptamers interact with …
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Direct QM/MM Simulations of the Excited State Dynamics of Retinal Protonated Schiff Base in Isolation and in Complex Environments
… bacteriorhodopsin (bR) and halorhodopsin (hR). Photoisomerization of RPSB from the all-trans to 13-cis conformation triggers ion transport across the cell membrane in hR and bR. Visual perception in the eye is initiated by RPSB isomerization from 11-cis to all-trans conformation in Rh. An …
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Partnering Photochemical Protocols With Anion Relay Chemistry: Application In The Total Synthesis Of Natural Products
… benzo-fused spiroketal skeleton and a late-stage photoisomerization/cyclization union tactic was developed to access the benzo-fused [3.3.1]-none core. This photochemical protocol discovered in the Smith Laboratory further proves to be a powerful tool to synthesize polycyclic structures, showcased …
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Photophysical transformations in molecules studied by ultrafast multi-pulse spectroscopy /
… the third object of investigation was the photoisomerization reaction of two symmetric polymethine dye compounds. PDP experiments demonstrated for the first time the presence of emissive and non-emissive state and the equilibrium between them. The non-emissive state is the main channel of …
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Molekulių fotofizikinių virsmų tyrimas ultrasparčiosios daugiaimpulsės spektroskopijos metodais /
… the third object of investigation was the photoisomerization reaction of two symmetric polymethine dye compounds. PDP experiments demonstrated for the first time the presence of emissive and non-emissive state and the equilibrium between them. The non-emissive state is the main channel of …
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Responsive polymers for dynamic modulation of bio-macromolecular transport properties
… the azobenzene can undergo reversible trans-cis photoisomerization leading to conformational isomers with significantly dissimilar dipole moments and hydrophobicities and thus different propensities to aggregate into nanoscale structures in aqueous media. Copolymers of 4methacryloyloxyazobenzene …
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