Sahar Mostafa | Tanta University (original) (raw)
Papers by Sahar Mostafa
Monatshefte Fur Chemie, 1998
Monatshefte Fur Chemie, 1998
Metal complexes of divalent copper (1-2), cobalt (3), and nickel (4) with mixed ligands acetylace... more Metal complexes of divalent copper (1-2), cobalt (3), and nickel (4) with mixed ligands acetylacetone (acac) and adenine were prepared and characterized by IR, mass spectra, elemental and thermal analysis. The X-ray crystal structures of {[Cu(acac) 2 (adenine)]ÁEtOH} complex (1) and {[Cu(acac) 2 (adenine)]ÁDMFÁH 2 O} (2) were determined. Compound (1) crystallizes in the triclinic space group P -1 with a = 7.547 Å , b = 7.828(3) Å , c = 17.791(6) Å , a = 79.538(6)°, b = 82.240(7)°, c = 86.010 (6)°, V = 1023.1(6) Å 3 , and Z = 2. Complex (1) forms a hydrogen bonded 2:2 complex {[Cu(acac) 2 (adenine)] 2 : [EtOH] 2 } arranged in bilayers. Complex (2) crystallizes in the triclinic space group P -1 with a = 7.828(2) Å , b = 8.095(2) Å , c = 16.995(5) Å , a = 78.508(5)°, b = 84.949(5)°, c = 89.285(5)°, V = 1051.2(5) Å 3 , and Z = 2.
Journal of The American Chemical Society, 2011
Tailoring the chemical reactivity of nanomaterials at the atomic level is one of the most importa... more Tailoring the chemical reactivity of nanomaterials at the atomic level is one of the most important challenges in catalysis research. In order to achieve this elusive goal, fundamental understanding of the geometric and electronic structure of these complex systems at the atomic level must be obtained. This article reports the influence of the nanoparticle shape on the reactivity of Pt nanocatalysts supported on γ-Al 2 O 3 . Nanoparticles with analogous average size distributions (∼0.8-1 nm), but with different shapes, synthesized by inverse micelle encapsulation, were found to display distinct reactivities for the oxidation of 2-propanol. A correlation between the number of undercoordinated atoms at the nanoparticle surface and the onset temperature for 2-propanol oxidation was observed, demonstrating that catalytic properties can be controlled through shape-selective synthesis.
Journal of The American Chemical Society, 2011
Unraveling the complex interaction between catalysts and reactants under operando conditions is a... more Unraveling the complex interaction between catalysts and reactants under operando conditions is a key step toward gaining fundamental insight in catalysis. We report the evolution of the structure and chemical composition of size-selected micellar Pt nanoparticles (∼1 nm) supported on nanocrystalline γ-Al 2 O 3 during the catalytic oxidation of 2-propanol using X-ray absorption fine-structure spectroscopy. Platinum oxides were found to be the active species for the partial oxidation of 2-propanol (<140°C), while the complete oxidation (>140°C) is initially catalyzed by oxygen-covered metallic Pt nanoparticles, which were found to regrow a thin surface oxide layer above 200°C. The intermediate reaction regime, where the partial and complete oxidation pathways coexist, is characterized by the decomposition of the Pt oxide species due to the production of reducing intermediates and the blocking of O 2 adsorption sites on the nanoparticle surface. The high catalytic activity and low onset reaction temperature displayed by our small Pt particles for the oxidation of 2-propanol is attributed to the large amount of edge and corner sites available, which facilitate the formation of reactive surface oxides. Our findings highlight the decisive role of the nanoparticle structure and chemical state in oxidation catalytic reactions.
Monatshefte Fur Chemie, 1998
Monatshefte Fur Chemie, 1998
Metal complexes of divalent copper (1-2), cobalt (3), and nickel (4) with mixed ligands acetylace... more Metal complexes of divalent copper (1-2), cobalt (3), and nickel (4) with mixed ligands acetylacetone (acac) and adenine were prepared and characterized by IR, mass spectra, elemental and thermal analysis. The X-ray crystal structures of {[Cu(acac) 2 (adenine)]ÁEtOH} complex (1) and {[Cu(acac) 2 (adenine)]ÁDMFÁH 2 O} (2) were determined. Compound (1) crystallizes in the triclinic space group P -1 with a = 7.547 Å , b = 7.828(3) Å , c = 17.791(6) Å , a = 79.538(6)°, b = 82.240(7)°, c = 86.010 (6)°, V = 1023.1(6) Å 3 , and Z = 2. Complex (1) forms a hydrogen bonded 2:2 complex {[Cu(acac) 2 (adenine)] 2 : [EtOH] 2 } arranged in bilayers. Complex (2) crystallizes in the triclinic space group P -1 with a = 7.828(2) Å , b = 8.095(2) Å , c = 16.995(5) Å , a = 78.508(5)°, b = 84.949(5)°, c = 89.285(5)°, V = 1051.2(5) Å 3 , and Z = 2.
Journal of The American Chemical Society, 2011
Tailoring the chemical reactivity of nanomaterials at the atomic level is one of the most importa... more Tailoring the chemical reactivity of nanomaterials at the atomic level is one of the most important challenges in catalysis research. In order to achieve this elusive goal, fundamental understanding of the geometric and electronic structure of these complex systems at the atomic level must be obtained. This article reports the influence of the nanoparticle shape on the reactivity of Pt nanocatalysts supported on γ-Al 2 O 3 . Nanoparticles with analogous average size distributions (∼0.8-1 nm), but with different shapes, synthesized by inverse micelle encapsulation, were found to display distinct reactivities for the oxidation of 2-propanol. A correlation between the number of undercoordinated atoms at the nanoparticle surface and the onset temperature for 2-propanol oxidation was observed, demonstrating that catalytic properties can be controlled through shape-selective synthesis.
Journal of The American Chemical Society, 2011
Unraveling the complex interaction between catalysts and reactants under operando conditions is a... more Unraveling the complex interaction between catalysts and reactants under operando conditions is a key step toward gaining fundamental insight in catalysis. We report the evolution of the structure and chemical composition of size-selected micellar Pt nanoparticles (∼1 nm) supported on nanocrystalline γ-Al 2 O 3 during the catalytic oxidation of 2-propanol using X-ray absorption fine-structure spectroscopy. Platinum oxides were found to be the active species for the partial oxidation of 2-propanol (<140°C), while the complete oxidation (>140°C) is initially catalyzed by oxygen-covered metallic Pt nanoparticles, which were found to regrow a thin surface oxide layer above 200°C. The intermediate reaction regime, where the partial and complete oxidation pathways coexist, is characterized by the decomposition of the Pt oxide species due to the production of reducing intermediates and the blocking of O 2 adsorption sites on the nanoparticle surface. The high catalytic activity and low onset reaction temperature displayed by our small Pt particles for the oxidation of 2-propanol is attributed to the large amount of edge and corner sites available, which facilitate the formation of reactive surface oxides. Our findings highlight the decisive role of the nanoparticle structure and chemical state in oxidation catalytic reactions.