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41.
Yusuf M. Al-Hiari Ali M. Qaisi Mustafa M. El-Abadelah Wolfgang Voelter 《Monatshefte für Chemie / Chemical Monthly》2006,137(2):243-248
Summary. A synthesis of 3-(4-methoxycarbonyl-2,6-dinitrophenyl)indole, its 2,6-diamino analog, and 3-(2-amino-4-trifluoromethyl-6-nitrophenyl)indole
is described. 4-(Trifluoromethyl)phenyl derivatives exhibit higher antibacterial potency than the former 4-(methoxycarbonyl)phenyl
homologs, while 3-(4-trifluoromethyl-2-nitrophenyl)indole was the most active agent in the series, with MIC ≈ 7 μg/cm3 against E. coli and S. aureus. 相似文献
42.
Two analogues of diphenylethene carrying phenanthrene (1-(9-phenanthryl)-1-phenylethene (PPE)) and anthracene (1-(2-anthryl)-1-phenylethene (APE)) units were used in radical polymerization of styrene (St) and methyl methacrylate (MMA) at 80 °C using AIBN as initiator. Because of the nature of the polymerization, the resulting polymers possess the corresponding chromophoric groups. Using the methodology of a DPE system, these labelled polymers were further used for the synthesis of block copolymers. In this way poly(methyl methacrylate)-b-poly(styrene) and poly(methyl methacrylate)-b-poly(acrylonitrile) with molar masses of 60,000-90,000 g/mol were synthesized. Incorporation of the chromophoric groups into both homo- and block copolymers was confirmed by spectral measurements. 相似文献
43.
This work reports on the synthesis of new unsymmetrically substituted phthalocyanines (M = Zn, Cu, Co, Ni) bearing three benzo-15-crown-5 units through oxy bridges and a nitro group. Phthalocyanines were prepared by a statistical condensation of 4-nitro phthalonitrile and 1-{[(benzo-15-crown-5)-4′-yl]oxy}phthalonitrile in the presence of anhydrous metal salts. All the target unsymmetrical phthalocyanines were separated by column chromatography and characterized elemental analyses, 1H NMR, IR, mass and UV–Vis spectral data. Electrochemical behaviors of Cu (II) phthalocyanine by cyclic voltammetry and differential pulse voltammetry techniques gave two common phthalocyanine ring reductions and one ring oxidation processes. Peak-to-peak separation of the processes II and III (388 mV) and the measure of gap (1.672 V) between the HOMO and LUMO for the complex, fits a phthalocyanine with electrochemically inactive metal center. 相似文献
44.
Rotation matrices were expressed in terms of Gaunt coefficients and complex spherical harmonics. The rotation matrices were calculated using two different ways. In the first, Gaunt coefficients and normalized complex spherical harmonics were directly calculated using binomial coefficients; in the second, Gaunt coefficients and complex spherical harmonics were recursively calculated. The methods were compared with respect to accuracy and computation time (CPU) for low and very high quantum numbers. 相似文献
45.
A new alcohol soluble functionalized vic-dioxime, bis-[(1-hydroxyhexyl)-(8,9-hydroxyimino)-7,10-dithiahexacosane (LH2), and its alcohol-soluble mono and dinuclear complexes (NiII, CuII, CoII, MnII, PdII and UO
2
II
) have been prepared from 6-mercapto-1-hexanol and (E,E)-dichloroglyoxime under high dilution basic conditions. Reactive polyalcohol moieties appended at the periphery of the oxime
containing two different heteroatoms (S-, O-), serve as a weak exocyclic binding sites for PdII and AgI metal ions and also provide solubility for the vic-dioxime complexes in low molecular-weight alcohols. Both mono-nuclear (LH)2M and homodinuclear (LH)2(UO2)2(OH)2 and heterotrinuclear (LH)2MM
2
′
Xn, where M = CoII M′ = PdII, X = Cl−, n = 4 and AgI X = NO
3
−
, n = 2) complexes have been obtained with a 1:2, 2:2, 3:2 metal/ligand ratio, respectively. Electronic spectra of the modified
vic-dioximes exhibit monitorable changes in UV. All mono and dinuclear-complexes are soluble in common organic solvents. The
elemental analysis, 1H-n.m.r, i.r., u.v–vis, and f.a.b.–m.s data and by cyclic and differential pulse voltammetry measurements are presented. 相似文献
46.
The stoichiometry and stability constant of metal complexes with 4-(3-methoxy-salicylideneamino)-5-hydroxynaphthalene-2,7-disulfonic
acid monosodium salt (H2L) and 4-(3-methoxysalicylideneamino)-5-hydroxy-6-(2,5-dichlorophenylazo)-2,7-naphthalene disulfonic acid monosodium salt
(H2L1) were studied by potentiometric titration. The stability constants of H2L and H2L1 Schiff bases have been investigated by potentiometric titration and u.v.–vis spectroscopy in aqueous media. The dissociation
constants of the ligand and the stability constants of the metal complexes were calculated pH-metrically at 25 °C and 0.1 m KCl ionic strength. The dissociation constants for H2L were obtained as 3.007, 7.620 and 9.564 and for H2L1, 4.000, 6.525, 9.473 and 10.423, respectively. The complexes were found to have the formulae [M(L)2] for M = Co(II), Ni(II), Zn(II) and Cu(II). The stability of the complexes follows the sequence: Zn(II) < Co(II) < Cu(II)
< Ni(II). The high stability of H2L1 towards Cu(II) and Ni(II) over the other ions is remarkable, in particular over Cu(II), and may be of technological interest.
Concentration distribution diagram of various species formed in solution was evaluated for ligands and complexes. The formation
of the hydrogen bonds may cause this increased stability of ligands. The pH-metric data were used to find the stoichiometry,
deprotonation and stability constants via the SUPERQUAD computer program. 相似文献
47.
A novel flow-injection amperometric method was proposed for the sensitive and enzymeless determination of hydrogen peroxide based on its electrocatalytic reduction at a palladium nanoparticle-modified pretreated pencil graphite electrode in a laboratory-constructed electrochemical flow cell. Cyclic voltammograms of the unmodified and modified electrodes were recorded in pH 7.0 phosphate buffer containing 0.10 M KCl at a scan rate of 50?mV s?1 for the investigation of electrocatalytic reduction of hydrogen peroxide at the palladium nanoparticle-modified pretreated pencil graphite electrode. Cyclic voltammograms of the pretreated pencil graphite electrode revealed an irreversible oxidation peak and a weak reduction peak of hydrogen peroxide at +1100?mV and –450?mV vs. an Ag/AgCl/KCl saturated reference electrode. However, the reduction of hydrogen peroxide was observed at –100?mV with an increase in current in the cyclic voltammograms of the palladium nanoparticle-modified pretreated pencil graphite electrode compared to the unmodified electrode. These results indicate that the palladium nanoparticle-modified pretreated pencil graphite electrode exhibits efficient electrocatalytic activity for the reduction of hydrogen peroxide. A linear concentration range was obtained between .01 and 10.0?mM hydrogen peroxide with a detection limit of 3.0 µM from flow injection amperometric current–time curves recorded in pH 7.0 phosphate buffer at –100?mV and a 2.0?mL min?1 flow rate. The novelty of this work relies on its use of a laboratory-constructed flow cell constructed for the pencil graphite electrode using these inexpensive, disposable, and electrochemically reactive modified electrodes for the amperometric determination of hydrogen peroxide in a flow injection analysis system. 相似文献
48.
In this study, the new vic-dioxime ligand (LH2) and its complexes with CoII, NiII, CuII, ZnII, CdII and UO2VI are described. The structures of these complexes were characterized by elemental analyses, i.r., 1H- and 13C-n.m.r. spectra, u.v.–vis. spectroscopy, magnetic susceptibility measurements, conductivity measurements and thermogravimetric
analyses (t.g.a.). 相似文献
49.
The host–guest complex of a proline–thiourea bipyridine trifluoromethanesulfonic acid salt can catalyze organocatalytic asymmetric reactions such as aldol, Michael, and Mannich in polar protic medium with high stereoselectivities. The privileged bipyridine backbone and the thiourea motif are essential to the activity and enantioselectivity through hydrogen bonding interactions. 相似文献
50.
A proline–thiourea host–guest complex has been described as a good catalyst for asymmetric reactions such as aldol and Mannich reactions. High stereoselectivities were obtained under optimal conditions. Thiourea was observed to have an important effect on the reactivity and selectivity, even in an unconventional nonpolar reaction medium and without the need to utilize low temperatures. This proline–thiourea host–guest system has the ability to participate in a hydrogen bonding network. 相似文献