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排序方式: 共有167条查询结果,搜索用时 15 毫秒
1.
Francesco Segatta David M. Rogers Naomi T. Dyer Ellen E. Guest Zhuo Li Hainam Do Artur Nenov Marco Garavelli Jonathan D. Hirst 《Molecules (Basel, Switzerland)》2021,26(2)
A fully quantitative theory of the relationship between protein conformation and optical spectroscopy would facilitate deeper insights into biophysical and simulation studies of protein dynamics and folding. In contrast to intense bands in the far-ultraviolet, near-UV bands are much weaker and have been challenging to compute theoretically. We report some advances in the accuracy of calculations in the near-UV, which were realised through the consideration of the vibrational structure of the electronic transitions of aromatic side chains. 相似文献
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We have monitored the spectra and kinetics of μ-oxo iron (III) tetraphenyl porphyrin. The spectral changes between 460 nm
and 770 nm were observed after excitation with 25 ps fwhm, 355 nm pulse. Kinetic studies from — 100 ps to 4 ns suggest that
after the immediate formation of the excited states a transient species is formed which we assign to the π-caion radical-ferrous
porphyrin pair. This pair decays with a time constant of 600 ps ± 100 ps leaving a small amount of disproportionation reaction
photoproducts. The spectra and kinetics of the transients, were not altered by concentration (0.15 OD – 1.0 OD at 571 nm),
solvent or addition of oxygen. 相似文献
7.
Alistair P. Rendell Martyn F. Guest Rick A. Kendall 《Journal of computational chemistry》1993,14(12):1429-1439
The recently developed parallel coupled-cluster algorithm of Rendell, Lee, and Lindh [Chem. Phys. Lett., 194 , 84 (1992)] is extended to allow four-indexed quantities containing one or two indices in the virtual orbital space to be stored across the global memory of distributed-memory parallel processors. Quantities such as the double-excitation amplitudes can now be distributed over multiple nodes, with blocks of data retrieved from remote nodes by the use of interrupt handlers. As an application of the new code, we have investigated the potential energy surface of the 2-hydroxypyridine/2-pyridone tautomers. Using large basis sets, the structure of each tautomer and the transition state connecting the two minima has been determined at the SCF level. The relative energy difference and the activation energy were then redetermined using the MP2, CCSD, and CCSD(T) methods. All calculations have been performed on Intel distributed-memory supercomputers. The largest coupled-cluster calculations contained over 2 million double-excitation amplitudes. © John Wiley & Sons, Inc. 相似文献
8.
Richard Le Sueur Matt Guest Lee Belding Melanie Pilkington Travis Dudding 《Tetrahedron letters》2019,60(32):150928
This work demonstrates how modulating hydrogen bonding between intermolecular, bifurcated, and intramolecular interactions can be used to tune the structural, electronic, and photophysical properties of cyclopropenium ions and their respective fluorophores. The basis of this switchability was examined using X-ray diffraction analysis, 1H NMR spectroscopy, DFT calculations, and fluorescence spectroscopy. 相似文献
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Lydia A. Panther Dr. Daniel P. Guest Dr. Andrew McGown Hugo Emerit Dr. Raysa Khan Tareque Dr. Arathy Jose Mr. Chris M. Dadswell Dr. Simon J. Coles Dr. Graham J. Tizzard Dr. Ramón González-Méndez Dr. Charles A. I. Goodall Prof. Mark C. Bagley Prof. John Spencer Dr. Barnaby W. Greenland 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(49):e202201444
Solvent-free synthesis by using a vibratory ball mill (VBM) offers the chance to access new chemical reactivity, whilst reducing solvent waste and minimising reaction times. Herein, we report the core functionalisation of N,N’-bis(2-ethylhexyl)-2,6-dibromo-1,4,5,8-naphthalenetetracarboxylic acid (Br2-NDI) by using Suzuki, Sonogashira and Buchwald–Hartwig coupling reactions. The products of these reactions are important building blocks in many areas of organic electronics including organic light-emitting diodes (OLEDs), organic field-effect transistors (OFETs) and organic photovoltaic cells (OPVCs). The reactions proceed in as little as 1 h, use commercially available palladium sources (frequently Pd(OAc)2) and are tolerant to air and atmospheric moisture. Furthermore, the real-world potential of this green VBM protocol is demonstrated by the double Suzuki coupling of a monobromo(NDI) residue to a bis(thiophene) pinacol ester. The resulting dimeric NDI species has been demonstrated to behave as an electron acceptor in functioning OPVCs. 相似文献
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It is demonstrated, using the ground state of the water molecule, that the contribution of triply excited configurations to electron correlation energies in closed-shell systems is more sensitive to the degree of completeness of the basis set than the component associated with quadruply excited configurations. The relative importance of the triply excited states increases more rapidly than that of the quadruple excitations, as the quality of the basis set is improved. 相似文献