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Marinescu G.,Institute of Physical Chemistry of the Romanian Academy | Marinescu G.,University of Bucharest | Marin G.,University of Bucharest | Madalan A.M.,University of Bucharest | And 3 more authors.
Crystal Growth and Design | Year: 2010

The self-assembly processes between binuclear [Zn2] and [Cu 2] complex cations and exo-bidentate ligands [trans-4,4'-azo-pyridine (azpy), 4,4'-bipyridine (4,4'-bipy), 1,2-bis(4-pyridyl)ethane (bpeta), 1,3-bis(4-pyridyl)propane (bpp)] generate two types of complexes: tetranuclear species with a rectangular topology and one-dimensional (1-D) coordination polymers: [{L2(μ-OH)Cu2}(μ-azpy)2{Cu 2(μ-OH)L2}][{L2(μ-OH)Cu 2(H2O)}(μ-azpy)2{(H2O)Cu 2(μ-OH)L2}](ClO4)8 (1); [{L 1Cu2(H2O)2}(μ-azpy) 2{Cu2L1(H2O)2}](ClO 4)4•(azpy)•2H2O (2); 1 ∞[{Cu2(μ-OH)L3}(μ-bpp)] (ClO4)2 (3); 1 ∞[{L 3Zn2(μ-OH)}(μ-4,4'-bipy)](ClO4) 2•2H2O (4); 1 ∞[{L 3Zn2(μ-OH)}(μ-bpeta)](ClO4)2 (5a); 1 ∞[{L3Zn2(μ-OH)} (μ-bpeta)](ClO4)2•THF (5b); 1 ∞[{L2Zn2(μ-OH)}(μ-4,4'- bipy)2](ClO4)2•2H2O (6) (H 2Ln are compartmental Schiff-base ligands resulting from condensation reactions between 2,6-diformyl-p-cresol with, respectively, 1,3-diamino-propane, 2-aminoethyl-pyridine, and N,N-dimethyl-ethylenediamine). The zinc complexes exhibit luminescence properties. © 2010 American Chemical Society. Source

Magureanu M.,Romanian National Institute for Lasers, Plasma and Radiation Physics | Piroi D.,Romanian National Institute for Lasers, Plasma and Radiation Physics | Mandache N.B.,Romanian National Institute for Lasers, Plasma and Radiation Physics | Parvulescu V.I.,University of Bucharest | And 6 more authors.
Applied Catalysis B: Environmental | Year: 2011

Silver colloids have been prepared by reducing AgNO3 in aqueous solution and embeded in alumina following a sol-gel procedure in the presence of Pluronic 84 ((EO)19(PO)39(EO)19), as surfactant. Plasma-catalytic experiments aimed at the mineralization of toluene showed that the selectivity to CO2 was significantly increased in the presence of Ag catalysts compared with results obtained using the plasma alone. In-situ studies of the ozone interaction with catalysts provide an insight into the nature of the active sites of supported silver colloids for mineralization reactions. It is noticeable that when ozone is chemisorbed on embedded Ag colloidal catalysts no change in the silver oxidation state or size is found. The population of the chemisorbed species is higher at lower temperatures, where the non-selective decomposition of ozone is smaller. The catalysts exhibit high stability, preserving the structural and textural properties after the catalytic tests, that is indeed very important in the presence of ozone. © 2011 Elsevier B.V. Source

Miyazaki A.,Japan Womens University | Numata M.,Japan Womens University | Etou M.,Fukuoka University | Yonezu K.,Fukuoka University | And 2 more authors.
Colloids and Surfaces A: Physicochemical and Engineering Aspects | Year: 2013

27Al magic-angle spinning nuclear magnetic resonance (MAS NMR) spectroscopy was used to investigate the effect of Zn2+ ion adsorption on Al(OH)3 gel. While as-prepared Al(OH)3 gel exhibits a single peak around 5ppm, the same gel with adsorbed Zn2+ has new peaks around 15 and 60ppm. These peaks correspond to AlO6 octahedral species with adsorbed Zn2+ and AlO4 tetrahedral species, respectively. In order to assess the mechanism for the formation of AlO4 tetrahedral species, hydroxide coprecipitates of Al3+ and Zn2+ were prepared and the chemical states of Al in the solids were observed by 27Al MAS NMR. The coprecipitates were found to have the AlO4 tetrahedral structure, except for those with high Zn/Al ratios. From these results, it can be assumed that adsorption of Zn2+ onto Al(OH)3 gel induces Al3+ dissolution followed by the coprecipitation of Al3+ with Zn2+ to form AlO4 tetrahedral structures on the surface of Al(OH)3 gel. © 2012 Elsevier B.V. Source

Perisanu S.,Polytechnic University of Bucharest | Contineanu I.,Institute of Physical Chemistry of the Romanian Academy | Neacsu A.,Institute of Physical Chemistry of the Romanian Academy | Rath N.P.,University of Missouri-St. Louis | And 3 more authors.
Structural Chemistry | Year: 2013

The crystalline and gas phase enthalpy of formation of 5-cyano-7H-dibenzo- [a,c]-cyclohepten-6-amine (1) (142.0 ± 11.6 and 264 ± 20 kJ mol-1, respectively) are reported. The sublimation enthalpy at T = 298.15 K for this compound was evaluated by combining the fusion enthalpy from DSC measurements adjusted to 298 K with estimated vaporization enthalpy. The experimental enthalpy of formation is discussed in relationship with values calculated at the G3(MP2)//B3LYP level of quantum chemical theory and by means of group additivity. The crystal structure of this compound was determined by X-ray crystallography and shown to exist entirely in the cyanoenamine form 1, i.e. not the tautomeric α-cyanoimine 2. © 2013 Springer Science+Business Media New York. Source

Papa F.,Institute of Physical Chemistry of the Romanian Academy | Negrila C.,National Institute of Materials Physics Bucharest | Miyazaki A.,Japan Womens University | Balint I.,Institute of Physical Chemistry of the Romanian Academy
Journal of Nanoparticle Research | Year: 2011

Well-dispersed, uniform monometallic Pt and bimetallic Pt-Cu, and Pt-Ag nanoparticles protected with PVP have been synthesized by a modified-protocol alkaline polyol method. The nanoparticles were characterized by various methods (TEM, XPS, and XRD) to elucidate the relationship between morphology and preparation variables. The average of monodispersed nanoparticles ranged between 4.1 and 4.9 nm. Core-shell structure was obtained in the case of bimetallic nanoparticles. The core of bimetallic nanoparticles was found to be rich in platinum, whereas the shell contained mostly copper or silver. The final structure of bimetallic nanoparticles was found to be determined by the morphology particles resulted in the first reduction step. Explanations are advanced on the light of experimental results. © 2011 Springer Science+Business Media B.V. Source

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