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51.
The intramolecular electrophilic substitution in 6-functionalized 1,3-dimethyl-1H-pyrrolo[3,4-d]pyrimidine-2,4(3H,6H)-diones was used for the synthesis of pyrimido[4′,5′:3,4]-pyrrolo[1,2-a]quinoxaline-8,10(7H,9H)-dione, pyrimido[4′,5′:3,4]pyrrolo[2,1-c][1,2,4]benzo-triazine-8,10(7H,9H)-dione, and 2H-pyrimido[4′,5′:3,4]pyrrolo[1,2-a]indole-2,4,11(1H, 3H)-trione derivatives.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2180–2185, December, 2006. 相似文献
52.
L. A. Kutulya A. E. Shevchenko L. D. Pchelinova 《Chemistry of Heterocyclic Compounds》1982,18(6):612-615
It was demonstrated by means of the IR and PMR spectra that 1-phenyl-3,5-diaryl-2-pyrazolines that contain a grouping with a strong electron-acceptor effect, viz. a 4-nitrophenyl or 4-naphthalanhydride group or a 1,8-naphthoylene-1,2-benzimidazole fragment, in the 3 position undergo Vilsmeier formylation, like unsubstituted 1,3,5-triphenyl-2-pyrazoline, in the para position of the 1-phenyl ring. An investigation of the spectral-luminescence properties of the synthesized 1-(4-formylphenyl)-3,5-diaryl-2-pyrazolines showed that the introduction in the 1-phenyl ring of an electron-acceptor aldehyde group, which is inferior with respect to its acceptor effect to the groupings in the 3 position of the heteroring, does not change the nature of the long-wave absorption band. Substantial hypsochromic and hypsofluoric effects as compared with the corresponding 1-phenyl-unsubstituted compounds are noted in the electronic spectra of these compounds.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 807–811, June, 1982.The authors thank I. D. Kalikhman for recording the PMR spectra. 相似文献
53.
Elena E. Ferapontova John Castillo Dmitri Hushpulian Vladimir Tishkov Tatiana Chubar Irina Gazaryan Lo Gorton 《Electrochemistry communications》2005,7(12):1291-1297
Direct electron transfer (DET) reactions of recombinant tobacco peroxidase (rTOP), namely direct electroreduction of Compound I/Compound II and heme Fe3+/2+ conversion, were studied on gold electrodes. rTOP of wild type, non-glycosylated, was produced using an Escherichia coli expression system. At pH 5.0, the redox potential for direct electrochemical transformation of the Fe3+/2+ of the peroxidase heme was −143 mV vs. AgAgCl, and 0.26 ± 0.07 pmol of the adsorbed rTOP were in DET contact with the gold electrode. The total amount of the adsorbed rTOP estimated from QCM data was 53 ± 5 pmol/cm2 or 1.67 pmol when referred to the surface area of the electrodes used for electrochemical measurements. Of 1.67 pmol of adsorbed rTOP, only 0.76 pmol were catalytically active. DET between Au and the enzyme was also studied in the reaction of the bioelectrocatalytic reduction of H2O2 by cyclic voltammetry and amperometric detection of H2O2 at +50 mV with rTOP-modified Au electrodes placed in a wall-jet flow-through electrochemical cell. Maximal bioelectrocatalytic current response of the rTOP-modified gold electrodes to H2O2 was observed at pH 5.0 and stemmed from its bioelectrocatalytic reduction based on DET between Au and the active site of rTOP. Kinetic analysis of the DET reactions gave 52% of the adsorbed rTOP molecules active in DET reactions (0.4 pmol of adsorbed catalytically active rTOP, correspondingly), which correlated well with the non-catalytic-voltammetry data. DET was characterised by a heterogeneous ET rate constant of 13.2 s−1, if one takes into account the QCM data, and 19.6 s−1, if the amount of rTOP estimated from the data on DET transformation of Fe3+/2+ couple of rTOP is considered. The sensitivity for H2O2 obtained for the rTOP-modified Au electrodes was 0.7 ± 0.1 A M−1 cm−2. These are the first ever-reported data on DET reactions of anionic plant peroxidases on bare gold electrodes. 相似文献
54.
Tegos GP Demidova TN Arcila-Lopez D Lee H Wharton T Gali H Hamblin MR 《Chemistry & biology》2005,12(10):1127-1135
Fullerenes are soccer ball-shaped molecules composed of carbon atoms, and, when derivatized with functional groups, they become soluble and can act as photosensitizers. Antimicrobial photodynamic therapy combines a nontoxic photosensitizer with harmless visible light to generate reactive oxygen species that kill microbial cells. We have compared the antimicrobial activity of six functionalized C(60) compounds with one, two, or three hydrophilic or cationic groups in combination with white light against gram-positive bacteria, gram-negative bacteria, and fungi. After a 10 min incubation, the bis- and tris-cationic fullerenes were highly active in killing all tested microbes (4-6 logs) under conditions in which mammalian cells were comparatively unharmed. These compounds performed significantly better than a widely used antimicrobial photosensitizer, toluidine blue O. The high selectivity and efficacy exhibited by these photosensitizers encourage further testing for antimicrobial applications. 相似文献
55.
Pinto FG Andrada D Magalhães CG Nunes BR de Amorim FR Franco MB Saint'pierre TD da Silva JB Curtius AJ 《Analytical and bioanalytical chemistry》2005,383(5):825-832
Different chemical modifiers for use with electrothermal atomic absorption spectrometry (ET AAS) were investigated in relation
to determining the selenium in human urine samples. The samples were diluted in a solution containing 1% v/v HNO3 and 0.02% m/v cetyltrimethylammonium chloride (CTAC). Studying the modifiers showed that the use of either Ru or Ir as the
permanent modifier gave low sensitivity to Se and the peak shape was very noisy, while Zr or Rh gave no peak at all. The same
occurred when Zr was used in solution. For mixtures of permanent modifiers, Ir plus Rh or Zr plus Rh gave very low sensitivity,
Zr plus Rh with co-injection of Ir in solution was also not efficient, Zr plus Rh in solution gave good sensitivity, but the
best results were obtained with a mixture of Zr and Rh as the permanent modifier and co-injection of Rh in solution. Using
this last modifier, the following dilutions with the HNO3 and CTAC were studied: 1:1, 1:2, 1:3 and 1:4. The best dilution was 1:1, which promoted good sensitivity and a more defined
peak shape and made it possible to correct for the background using a deuterium arc lamp. Under these conditions, a characteristic
mass of 26±0.2 pg was obtained for Se in aqueous solution. Six certified urine samples were analyzed using matrix matching
calibration and the measured concentrations were in agreement with the certified values, according to a t-test at the 95%
confidence level. Recovery tests were carried out and the recoveries were in the range 100–103%, with relative standard deviation
better than 9%. The limit of detection (LOD, 3 sd, n=10) was 3.0 μg L−1 in the sample. The treated graphite tube could be used for at least 600 atomization cycles without significant alteration
of the analytical signal. 相似文献
56.
Alvarez CM Alvarez MA García-Vivó D García ME Ruiz MA Saáez D Falvello LR Soler T Herson P 《Dalton transactions (Cambridge, England : 2003)》2004,(24):4168-4179
The new hydride complexes [Mo2Cp2(mu-H)(mu-PHR)(CO)4] having bulky substituents (R = 2,4,6-C(6)H2tBu3= Mes*, R = 2,4,6-C6H2Me3= Mes) have been prepared in good yield by addition of Li[PHR] to the triply bonded [Mo2Cp2(CO)4] and further protonation of the resulting anionic phosphide complex [Mo2Cp2(mu-PHR)(CO)4]-. Protonation of the Mes* compound with either [H(OEt2)2][B{3,5-C6H3(CF3)2}4] or HBF4.OEt2 gives the cationic phosphinidene complex [Mo2Cp2(mu-H)(mu-PMes*)(CO)4]+ in high yield. In contrast, protonation of the analogous hydride compounds with Mes or Cy substituents on phosphorus give the corresponding unsaturated tetracarbonyls [Mo2Cp2(mu-PHR)(CO)4]+, which are unstable at room temperature and display a cis geometry. Decomposition of the latter give the electron-precise pentacarbonyls [Mo2Cp2(mu-PHR)(mu-CO)(CO)4]+, also displaying a cis arrangement of the metal fragments. In the presence of BF4- as external anion, fluoride abstraction competes with carbonylation to yield the neutral fluorophosphide hydrides [Mo2Cp2(mu-H)(mu-PFR)(CO)4]. Similar results were obtained in the protonation reactions of the hydride compounds having a Ph substituent on phosphorus. In that case, using HCl as protonation reagent gave the chloro-complex [Mo2ClCp2(mu-PHPh)(CO)4] in good yield. The structures and dynamic behaviour of the new compounds are analyzed on the basis of solution IR and 1H, 31P, 19F and 13C NMR data as well as the X-ray studies carried out on [Mo2Cp2(mu-H)(mu-PHMes)(CO)4](cis isomer), [Mo2Cp2(mu-H)(mu-PFMes)(CO)4](trans isomer), [Mo2Cp2(mu-PHCy)(mu-CO)(CO)4](BF4) and [Mo2ClCp2(mu-PHPh)(CO)4]. 相似文献
57.
Jones SC Coropceanu V Barlow S Kinnibrugh T Timofeeva T Brédas JL Marder SR 《Journal of the American Chemical Society》2004,126(38):11782-11783
A complex featuring two triarylamine redox centers bridged by Pt, trans-bis(triethylphosphine)-bis{4-[bis(4-methoxyphenyl)amino]phenylethynyl} platinum(II), has been synthesized as a model system for pi-conjugated Pt-containing polymers. Analysis of the intervalence charge-transfer band displayed by its mixed-valence monocation affords a quantitative assessment of electronic delocalization through the Pt bridge; this is found to be only slightly smaller than that determined for a benzene-bridged analogue. These results are supported by density functional theory calculations, which show that the active orbitals involved in the electron-transfer process in both cases have similar delocalization through the bridging unit. 相似文献
58.
A. P. Kilimov M. A. Svechnikova V. I. Shevchenko V. V. Smirnov S. B. Zotov F. V. Kvasnyuk-Mudryi 《Chemistry of Heterocyclic Compounds》1969,5(2):156-159
The IR spectra of six monosubstituted and of four 2,6-disubstituted 1,4-dioxanes have been studied in the 650–1800cm–1 region. The assignment of the bands due to the vibrations of the 1,4-dioxane ring and to the deformation vibrations of the methylene groups of the ring is given. The appearance of a whole series of new absorption bands on passing from unsubstituted 1,4-dioxane to its derivatives is explained by the change in the symmetry of the molecule and the removal of the prohibition from the vibrations previously inactive in the IR spectra connected with this reduction in symmetry. It is proposed to use, in order to confirm the presence of a 1,4-dioxane ring in a molecule from the results of IR spectroscopy, not only the 1126-cm–1 band but the whole group of bands lying in the frequency ranges 800–950, 1000–1150, and 1200–1300 cm–1.For part I, see [3]. 相似文献
59.
Mircho Georgiev Tatiana Popova Zhorro S. Nickolov Nikolay Goutev Georgi Georgiev Hiroatsu Matsuura 《Central European Journal of Chemistry》2004,2(4):617-626
The hypothesis that the degree of hydration of poly(oxyethylene) (POE) in aqueous solution depends on the mole ratio of water
molecules to ether oxygen atoms in the molecule has been verified by studying the isotropic Raman spectra in the O−H stretching
region for four short-chain POEs (C 1E
n
C 1 withn=1−4). Excellent coincidence of the O−H stretching Raman band for all four POEs studied in the range of mole ratio H2O/O
ether
from 25 to 0.6 was observed, thus confirming the assumption stated above. A conclusion that all ether oxygen atoms in the
POE molecule participate in hydrogen bonding with water molecules has been made. 相似文献