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排序方式: 共有249条查询结果,搜索用时 15 毫秒
141.
Nag S Ferreira JG Chenneberg L Ducharme PD Hanan GS La Ganga G Serroni S Campagna S 《Inorganic chemistry》2011,50(1):7-9
Two new bidentate ligands (1 and 2) with bicyclic guanidine moieties were synthesized and attached to a Ru(II)(bpy)(2) core (bpy = 2,2'-bipyridine) to afford complexes 3 and 4, which were characterized by spectroscopic and electrochemical methods. Complex 4 was further characterized by X-ray crystallography. In cyclic voltammetric studies, both complexes show a Ru(II/III) couple, which is 500 mV less positive than the Ru(II/III) couple of Ru(bpy)(3)(2+). The (1)MLCT and (3)MLCT states of 3 (560 nm/745 nm) and 4 (550 nm/740 nm) are significantly red-shifted with respect to Ru(bpy)(3)(2+) (440 nm/620 nm). Compounds 3 and 4 exhibit emission from a Ru(II)-to-bpy (3)MLCT state, which is rarely the emitting state at λ > 700 nm in [Ru(bpy)(2)(N-N)](2+) complexes. 相似文献
142.
Werrett MV Chartrand D Gale JD Hanan GS MacLellan JG Massi M Muzzioli S Raiteri P Skelton BW Silberstein M Stagni S 《Inorganic chemistry》2011,50(4):1229-1241
The synthesis, structural, and photophysical properties of a novel family of neutral fac-[Re(N(∧)N)(CO)(3)(L)] complexes, where N(∧)N is either 2,2'-bipyridine or 1,10-phenanthroline and L is a para functionalized 5-aryltetrazolate [namely, 5-phenyltetrazolate (Tph(-)), 4-(tetrazolate-5-yl)benzaldehyde (Tbdz(-)), 5-(4-acetylphenyl)tetrazolate (Tacy(-)), and methyl 4-(tetrazolate-5-yl)benzoate (Tmeb(-))] are reported. The complexes were prepared by direct addition of the corresponding tetrazolate anion to the acetonitrile solvated fac-[Re(N(∧)N)(CO)(3)](+) precursor. NMR data demonstrate that the coordination of the metal fragment is regiospecific at the N2 atom of the tetrazolate ring. These conclusions are also supported by X-ray structural determinations. Photophysical data were obtained in diluted and deaerated dichloromethane solutions displaying broad and structureless profiles with emission maxima ranging from 566 to 578 nm. The absorption profiles indicate the presence of higher energy intraligand (IL) π-π* transitions and lower energies ligand-to-ligand charge transfer (LLCT) and metal-to-ligand charge transfer (MLCT). As the last two transitions are mixed, they are better described as a metal-ligand-to-ligand charge transfer (MLLCT), a result that is also supported by density functional theory (DFT) calculations. The complexes show excited state lifetime values ranging from 102 to 955 ns, with associated quantum yield between 0.012 and 0.099. Compared to the parent neutral chloro or bromo [Re(N(∧)N)(CO)(3)X], the complexes show a slightly improved performance because of the π accepting nature of the tetrazolato ligand. The metal-to-ligand backbonding is in fact depleting the Re center of electron density, thus widening the HOMO-LUMO gap and reducing the non-radiative decay mechanism in accordance with the energy gap law. Finally, the electron-withdrawing or donating nature of the substituent on the phenyltetrazolato ligand allows the fine-tuning of the photophysical properties. 相似文献
143.
Chloro axially-substituted octa(4-isopropylphenoxy)rhodium(III)phthalocyanine, (R)8PcRhCl (3), was reacted with the nitrogenous bases pyridine (Py) and pyrazine (Pyz) to give the axially-disubstituted octa(4-isopropylphenoxy)rhodium(III)phthalocyanines [(R)8PcRhCl(L)] (4) and (5), L = (Py) and (Pyz), respectively. In this study, the fluorescence quantum yield (ΦF), the phosphorescence quantum yield (Φphos) and the photodegradation quantum yield (Φpd) values for the newly synthesized rhodium phthalocyanine complexes (RhPcs) 4 and 5 are reported. The complexes have also been fully characterized by elemental analysis, FD mass spectrometry, FT-IR and 1H NMR spectroscopy. 相似文献
144.
Hanan H. Mohamed Ralf Dillert Detlef W. Bahnemann 《Journal of photochemistry and photobiology. A, Chemistry》2011,217(1):271-274
The dynamics of the transfer of electrons from TiO2 nanoparticles to a variety of electron acceptors have been investigated employing a simple and facile stopped flow technique. Prior to the kinetic experiments nanosized TiO2 particles are loaded with electrons by UV (A) photolysis in the presence of methanol as a hole scavenger. As a model for possible electron transfer reactions the reduction of dissolved O2 and H2O2 by stored TiO2 electrons has been successfully studied. 相似文献
145.
El-Mahdy Reham I. Mostafa Mohammed Mahmoud EL-Deen Hanan Sharaf 《Applied biochemistry and biotechnology》2019,188(1):208-224
Applied Biochemistry and Biotechnology - Despite advances in the management of cardiovascular diseases, acute coronary syndrome (ACS) remains the leading cause of death worldwide. ACS is associated... 相似文献
146.
Dr. Dario Formenti Dr. Rita Mocci Dr. Hanan Atia Dr. Sarim Dastgir Dr. Muhammad Anwar Dr. Stephan Bachmann Dr. Michelangelo Scalone Dr. Kathrin Junge Prof. Dr. Matthias Beller 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(67):15589-15595
Cobalt-doped hybrid materials consisting of metal oxides and carbon derived from chitin were prepared, characterized and tested for industrially relevant nitrile hydrogenations. The optimal catalyst supported onto MgO showed, after pyrolysis at 700 °C, magnesium oxide nanocubes decorated with carbon-enveloped Co nanoparticles. This special structure allows for the selective hydrogenation of diverse and demanding nitriles to the corresponding primary amines under mild conditions (e.g. 70 °C, 20 bar H2). The advantage of this novel catalytic material is showcased for industrially important substrates, including adipodinitrile, picolinonitrile, and fatty acid nitriles. Notably, the developed system outperformed all other tested commercial catalysts, for example, Raney Nickel and even noble-metal-based systems in these transformations. 相似文献
147.
Othman A. Hamed Arab El-Qisairi Hanan Qaseer Emad M. Hamed Patrick M. Henry Daniel P. Becker 《Tetrahedron letters》2012,53(22):2699-2701
The oxidation of ketones by a chiral bimetallic palladium(II) complex in the presence of CuCl2 in THF–water solvents gave an enantioselective synthesis of α-hydroxyketones in catalytic oxidation utilizing an atmosphere of oxygen. The ee’s ranged from 61% to 92%. The reaction was accelerated by addition of strong acid that presumably increases the rate of enolization. 相似文献
148.
Synthesis,characterization and anticancer studies of ferrocenyl complexes containing thiazole moiety
Mokhles M. Abd‐Elzaher Samia A. Moustafa Ammar A. Labib Hanan A. Mousa Mamdouh M. Ali Abeer E. Mahmoud 《应用有机金属化学》2012,26(5):230-236
A ferrocenyl ligand was prepared from condensation of l,l′‐diacetylferrocene with 2‐amino‐5‐methylthiazole, to give the ligand. This ligand forms 1:1 complexes with lead(II), cobalt(II), nickel(II), copper(II) and zinc(II) in good yield. Characterization of the ligand and complexes was carried out using IR, NMR, electronic absorption, magnetic susceptibility, molar conductivity and elemental analysis. Anticancer activity of the prepared ligand and its complexes against breast cancer cell line MCF‐7 was determined. The anticancer activity of the new complexes was accompanied by significant increase in the activity of superoxide dismutase, with a parallel decrease in the activities of catalase and glutathione peroxidase and reduced glutathione level. Accordingly, the overproduction of free radicals allowed reactive oxygen species‐mediated cancer cell death. The results suggest that the complexes possess significant anticancer activity comparable to cisplatin. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
149.
B. Winiarski M. Benedetti V. Fontanari M. Allahkarami J. C. Hanan P. J. Withers 《Experimental Mechanics》2016,56(8):1449-1463
150.
Wang J Fang YQ Bourget-Merle L Polson MI Hanan GS Juris A Loiseau F Campagna S 《Chemistry (Weinheim an der Bergstrasse, Germany)》2006,12(33):8539-8548
A new family of ruthenium(II) complexes with multichromophoric properties was prepared based on a "chemistry-on-the-complex" synthetic approach. The new compounds are based on tridentate chelating sites (tpy-type ligands, tpy=2,2':6',2'-terpyridine) and most of them carry appended anthryl chromophores. Complexes 2 a and 2 b were synthesized through the Pd-catalyzed Suzuki coupling reaction between 9-anthrylboronic acid and the chloro ligands on the presursor species 1 a and 1 b, respectively. The monocoupling product 2 c was also synthesized as the starting complex for a dimetallic complex under optimized Suzuki coupling conditions. The palladium(0)-catalyzed homocoupling reaction on complexes 1 a and 2 c led to dimetallic Ru(II) species 2 d and 2 e, respectively. The solid structures of complexes 2 a and 2 b were characterized by X-ray diffraction. The absorption spectra, redox behavior, luminescence properties (both at room temperature and at 77 K), and transient absorption spectra and decays of 2 a-e were investigated. The absorption spectra of all new species are dominated by ligand-centered (LC) bands in the UV region and metal-to-ligand charge-transfer (MLCT) bands in the visible region. The new compounds undergo reversible metal-centered oxidation processes and several ligand-centered reduction processes, which have been assigned to specific sites. The complexes exhibit luminescence both at room temperature in fluid solution and at 77 K in rigid matrices; the emission was attributed to (3)MLCT states at room temperature and to the lowest-lying anthracene triplet ((3)An) at low temperature, except for 2 c, which does not contain any anthryl chromophore and whose low temperature emission is also of MLCT origin. The luminescence lifetimes of complexes 2 a-d showed that multichromophoric behavior occurs in these species, allowing the luminescence lifetime of the Ru(II)-based chromophores to be prolonged to the microsecond timescale, with the anthryl groups behaving as energy-storage elements for the repopulation of the (3)MLCT state. Nanosecond transient-absorption spectroscopy confirmed the equilibration process between the triplet MLCT and An levels at room temperature. Thermodynamic and kinetic factors governing the equilibration time and the lifetime of the equilibrated excited state are discussed. 相似文献