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481.
Ehrlich LA Skrdla PJ Jarrell WK Sibert JW Armstrong NR Saavedra SS Barrett AG Hoffman BM 《Inorganic chemistry》2000,39(18):3963-3969
We describe the complete synthesis and characterization of a new family of peripherally functionalized porphyrazines (pz's) with four, three, or two (in a trans conformation) bis[thioethoxy(ethoxy)ethanol] moieties appended at the pyrroles. These "polyetherol" groups serve as weak exocyclic binding sites for a number of metal ions and also provide solubility of the pz's in low molecular-weight alcohols and water. Electronic spectra of the modified porphyrazines exhibit distinct changes in the visible region (both absorbance and fluorescence) in response to treatment with Ag+, Pb2+, Cd2+, Cs+, and Ni2+ in solution. Such properties make these compounds intriguing candidates for incorporation into the transducer layers in optically based chemical sensors. 相似文献
482.
M. B. Amelchakov N. S. Barbashina A. G. Bogdanov D. V. Chernov D. M. Gromushkin V. V. Kindin R. P. Kokoulin K. G. Kompaniets G. Mannocchi O. S. Matveeva A. A. Petrukhin D. A. Room O. Saavedra V. V. Shutenko D. A. Timashkov G. Trinchero E. E. Yanson I. I. Yashin 《Physics of Atomic Nuclei》2007,70(1):175-183
The first experimental results on a new EAS observable, the local muon density spectra measured with a large area coordinate
detector DECOR in a wide range of zenith angles, are presented. These data correspond to the interval of primary particle
energies from 1015 to 1018 eV. Some features of local muon density phenomenology are considered on the basis of an analytical model. Expected distributions
of the events in the muon density have been calculated by means of the CORSIKA code and compared with experimental data.
The text was submitted by the authors in English. 相似文献
483.
Experimental observation of phase (i.e. refractive index) component in the dynamic gratings recorded in erbium-doped optical fiber with saturation of optical absorption is reported. We utilized configuration of transient two-wave mixing with rectangular phase modulation of one of counterpropagating recording waves, where unshifted phase grating resulted in a transient energy exchange. The reported experiments were performed with heavily doped (≈5400 ppm erbium) fibers in a wide spectral range of Er3+ fundamental absorption at selected laser wavelengths 1492, 1526, 1549, and 1568 nm. Relative contribution of phase grating was especially large (up to ≈100% of the maximal amplitude component) at the opposite sides of the investigated spectral range and was significantly lower in its central part. The amplitude grating was found especially strong at short wavelength side of the spectrum (i.e. at 1492 nm), where the grating amplitude proved to be only two times lower than the theoretically predicted from consideration of two-level model. 相似文献
484.
I. I. Yashin N. V. Ampilogov I. I. Astapov N. S. Barbashina V. V. Borog A. N. Dmitrieva R. P. Kokoulin K. G. Kompaniets G. Mannocchi A. S. Mikhailenko A. A. Petrukhin O. Saavedra G. Trinchero V. V. Shutenko E. I. Yakovleva 《Bulletin of the Russian Academy of Sciences: Physics》2013,77(5):554-557
Muon diagnostics is a technique for the remote monitoring of various dynamic processes in the heliosphere and the Earth’s magnetosphere and atmosphere, based on analyzing spatial and angular variations in the flux of muons detected simultaneously from all directions in the upper hemisphere. Approaches to data analysis and some of the results of studies of the atmospheric and extra-atmospheric processes detected using the URAGAN muon hodoscope are discussed. 相似文献
485.
Nandurdikar RS Keefer LK Saavedra JE 《Chemical communications (Cambridge, England)》2011,47(23):6710-6712
Synthesis of previously inaccessible, potentially liver selective HNO donor V-IPA/NO ([iPrHN(3)-N(1)(O(1))=N(2)-O(2)-R], where R = vinyl) is reported here. A novel fluoride-labile TOM group at O-2 in conjunction with MOM protection at N-3 in IPA/NO is employed. The strategy developed is also extended to synthesis of other NO-releasing prodrugs and has applications in diversity-oriented synthesis of HNO- and NO-prodrugs. 相似文献
486.
Dr. Prashanth K. Poddutoori Niloofar Zarrabi Dr. Andrey G. Moiseev Roger Gumbau‐Brisa Dr. Serguei Vassiliev Prof. Art van der Est 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(9):3148-3161
Two self‐assembled supramolecular donor–acceptor triads consisting of AlIII porphyrin (AlPor) with axially bound naphthalenediimide (NDI) as an acceptor and tetrathiafulvalene (TTF) as a secondary donor are reported. In the triads, the NDI and TTF units are attached to AlIII on opposite faces of the porphyrin, through covalent and coordination bonds, respectively. Fluorescence studies show that the lowest excited singlet state of the porphyrin is quenched through electron transfer to NDI and hole transfer to TTF. In dichloromethane hole transfer to TTF dominates, whereas in benzonitrile (BN) electron transfer to NDI is the main quenching pathway. In the nematic phase of the liquid crystalline solvent 4‐(n‐pentyl)‐4′‐cyanobiphenyl (5CB), a spin‐polarized transient EPR spectrum that is readily assigned to the weakly coupled radical pair TTF.+NDI.? is obtained. The initial polarization pattern indicates that the charge separation occurs through the singlet channel and that singlet–triplet mixing occurs in the primary radical pair. At later time the polarization pattern inverts as a result of depopulation of the states with singlet character by recombination to the ground state. The singlet lifetime of TTF.+NDI.? is estimated to be 200–300 ns, whereas the triplet lifetime in the approximately 350 mT magnetic field of the X‐band EPR spectrometer is about 10 μs. In contrast, in dichloromethane and BN the lifetime of the charge separation is <10 ns. 相似文献
487.
The synthesis and liquid crystalline properties of a new series of diacylhydrazine derivatives (2a–g) are reported. All compounds of series 2 exhibit a smectic C (SmC) phase. The first homologues (2a, 2b) display a monotropic SmC mesophase, whereas the highest homologues (2c–g) exhibit an enantiotropic SmC phase. The liquid crystalline properties were investigated by differential scanning calorimetry, polarizing optical microscopy and X‐ray measurements. 相似文献
488.
The oxidation of β-hydroxynitrosamines to the corresponding β-ketonitrosamine is reported. The reactions carried out in benzene or dichloromethane using powdered KMnO4-CuSO4.5H2O, or KMnO4-MgSO4.7H2O. Work-up of the reaction and purification of the product requires only a filtration through magnesium sulfate and chromatography through a short Florisil column. 相似文献
489.
Mark D. Ogden Cortney L. Hoch Serguei I. Sinkov G. Patrick Meier Gregg J. Lumetta Kenneth L. Nash 《Journal of solution chemistry》2011,40(11):1874-1888
A new bidentate nitrogen donor complexing agent that combines pyridine and triazole functional groups, 2-((4-phenyl-1H-1,2,3-triazol-1-yl)methyl)pyridine (PTMP), has been synthesized. The strength of its complexes with trivalent americium (Am3+) and neodymium (Nd3+) in anhydrous methanol has been evaluated using spectrophotometric techniques. The purpose of this investigation is to assess
this ligand (as representative of a class of similarly structured species) as a possible model compound for the challenging
separation of trivalent actinides from lanthanides. This separation, important in the development of advanced nuclear fuel
cycles, is best achieved through the agency of multidentate chelating agents containing some number of nitrogen or sulfur
donor groups. To evaluate the relative strength of the bidentate complexes, the derived constants are compared to those of
the same metal ions with 2,2′-bipyridyl (bipy), 1,10-phenanthroline (phen), and 2-pyridin-2-yl-1H-benzimidazole (PBIm). At issue is the relative affinity of the triazole moiety for trivalent f element ions. For all ligands,
the derived stability constants are higher for Am3+ than Nd3+. In the case of Am3+ complexes with phen and PBIm, the presence of 1:2 (AmL2) species is indicated. Possible separations are suggested based on the relative stability and stoichiometry of the Am3+ and Nd3+ complexes. It can be noted that the 1,2,3-triazolyl group imparts a potentially useful selectivity for trivalent actinides
(An(III)) over trivalent lanthanides (Ln(III)), though the attainment of higher complex stoichiometries in actinide compared
with lanthanide complexes may be an important driver for developing successful separations. 相似文献
490.
Tuer A Krouglov S Cisek R Tokarz D Barzda V 《Journal of computational chemistry》2011,32(6):1128-1134
With polarization dependent second harmonic generation (SHG) microscopy becoming a more popular method for investigating the structure of biological materials, there is a need to develop tools with which to understand and interpret the observed SHG properties. Quantum mechanical calculations of the hyperpolarizability tensor have become a popular method for understanding the SHG properties of biomolecules. Visualization of the full hyperpolarizability tensor, termed the unit sphere representation, has been developed to provide insight and intuition on the relationship between SHG properties and molecules. A single vector representation is also presented, which approximates the SHG properties of molecules for certain cases, where the anisotropy is negligible. 相似文献