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1.
The oxidation of alkyl chlorides and bromides with dimethyl sulfoxide has been performed in the presence of sodium iodide. This method allows a convenient one-step procedure for the preparation of aldehydes from alkyl chlorides and bromides. 相似文献
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Exciton‐Vibrational Couplings in Homo‐ and Heterodimer Stacks of Perylene Bisimide Dyes within Cyclophanes: Studies on Absorption Properties and Theoretical Analysis 下载免费PDF全文
David Bialas Christoph Brüning Dr. Felix Schlosser Dr. Benjamin Fimmel Johannes Thein Prof. Dr. Volker Engel Prof. Dr. Frank Würthner 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(42):15011-15018
The optical properties of a series of three cyclophanes comprising either identical or different perylene bisimide (PBI) chromophores were studied by UV/Vis absorption spectroscopy and their distinctive spectral features were analyzed. All the investigated cyclophanes show significantly different absorption features with respect to the corresponding constituent PBI monomers indicating strong coupling interactions between the PBI units within the cyclophanes. DFT calculations suggest a π‐stacked arrangement of the PBI units at close van der Waals distance in the cyclophanes with rotational displacement. Simulations of the absorption spectra based on time‐dependent quantum mechanics properly reproduced the experimental spectra, revealing exciton‐vibrational coupling between the chromophores both in homo‐ and heterodimer stacks. The PBI cyclophane comprising two different PBI chromophores represents the first example of a PBI heterodimer stack for which the exciton coupling has been investigated. The quantum dynamics analysis reveals that exciton coupling in heteroaggregates is indeed of similar strength as for homoaggregates. 相似文献
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Abstract The ability of phosphonic acid analogues isosteric with natural phosphate esters to Serve as inhibitors of enzymatic phosphate hydrolysis has been documented in a wide variety of systems.1 The use of such an analogue in place of the natural phosphate ester provides a functionality which the enzyme may not be able to distinguish from the natural ester, but which is incapable of being hydrolyzed. In some instances the use of hydroxymethylene analogues has resulted in a greater degree of recognition, and resultant inhibition of hydrolytic activity, than the simple methylene analogues.2 On this basis, the methylene and hydroxymethylene analogues of tyrosine O-phosphate appear to be reasonable candidates to Serve as inhibitors for phosphoprotein phosphatases and alkaline phosphatase, and as probes for biological mechanisms. 相似文献
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Gregory S. Engel 《Procedia Chemistry》2011,3(1):222-231
Quantum coherence improves the quantum efficiency of excitonic energy transport within the Fenna-Matthews-Olson photosynthetic complex from the green sulphur bacterium, Chlorobium tepidum. Experimental evidence from third-order nonlinear spectroscopies provides clear evidence of quantum coherence among excited states persisting for picoseconds despite rapid (<100fs) dephasing of quantum coherence between ground and excited states. This protection of quantum coherence can arise from multiple mechanisms, but the net effect is the same: the energetic landscape is course-grained thereby improving efficiency by effectively smoothing the rugged energetic landscape while simultaneously eliminating trap states. The protein bath enables the unusual observed dynamics and illustrates some simple design principles that provide direction to synthetic efforts to mimic the effect. This communication provides an overview of experimental and theoretical notions for those interested in exploiting design principles of photosynthetic energy transfer in synthetic systems. 相似文献
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Engel T. G. Veracka M. J. Neri J. M. 《IEEE transactions on plasma science. IEEE Nuclear and Plasma Sciences Society》2010,38(2):194-198
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Ethyl-2-(4-[(5R)-3-[4-(methoxycarboxamidoiminomethyl)-phenyl] -2-oxo-5-oxazolidinylmethyl]-1-piperazinyl) acetate, a glycoprotein IIb/IIIa antagonist, is a drug substance of the oxazolidinone type from Merck's research to be developed for the chronic oral treatment of thrombotic disorders. For the separation of the byproducts in the bulk drug substance, a reversed-phase HPLC gradient separation was developed. The eluent consisting of a nonvolatile phosphate buffer system had to be changed to a volatile acetate buffer system in order to perform on-line LC-MS coupling.With a triple quadrupole system it was possible to characterize most of the unknown byproducts occuring during synthesis and during scale-up to kg amounts of the bulk drug substance. 相似文献
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