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Hydrogen bonding-based 3D supramolecular architecture of [Cu(CHA)2][TCM]·11H2O

100%

Vlassa M., Borodi G., Silvestru C., Vlassa M.

Open Chemistry

2014

vol. 12

issue 1

14-24

Reaction of Na4TCM (1) (H4TCM = tetra[4-(carboxyphenyl)oxamethyl]methane) with [Cu(CHA)](ClO4)2 (2)(CHA = 1,3,6,8,11,14-hexaaz atricyclo[12.2.1.1.8,11] octadecane) in a DMF-water mixture yields [Cu(CHA)]2[TCM] (3). Structural analysis of [Cu(CHA)]2[TCM]·11H2O (3·11H2O) by single crystal X-ray diffraction reveals strong copper-oxygen bonds between two complex cations and the tetraanion leading to a 3D coordination network (zwitterionic structure), consolidated through additional NH...O=C hydrogen bonding within the cation/anion association. The resulting coordination geometry around a copper atom is a distorted square pyramidal with an oxygen atom of the anionic ligand in the apical position. A 3D supramolecular network is developed in the crystal based only on NH...OC hydrogen bonds between the macrocyclic metallic tecton and the carboxylate groups of neighboring 3D coordinated (zwitterionic) moieties. The pseudotetrahedral TCM4− tetraanionic ligand induces a diamondoid architecture formed of large distorted adamantanoid cages. [...]

Catalytic reduction of sulfuric acid to sulfur dioxide

88%

Balla A., Marcu C., Axente D., Borodi G., Lazăr D.

Open Chemistry

2012

vol. 10

issue 6

1817-1823

The reduction of H2SO4 to SO2 occurs with a relatively good efficiency only at high temperatures, in the presence of catalysts. Some experimental results, regarding conversion of sulfuric acid (96 wt.%) to sulfur dioxide and oxygen, are reported. The reduction has been performed at 800 – 900°C and atmospheric pressure, in a tubular quartz reactor. The following commercial catalysts were tested: Pd/Al2O3 (5 wt.% and 0.5 wt.% Pd), Pt/Al2O3 (0.1 wt.% Pt) and α-Fe2O3. The fresh and spent catalysts were characterized by X-Ray diffraction and BET method. The highest catalytic activity was determined for 5 wt.% Pd/Al2O3, a conversion of 80% being obtained for 5 hours time on stream, at 9 mL h−1 flow rate of 96 wt.% H2SO4. A conversion of 64% was determined for 0.5 wt.% Pd/Al2O3 and 0.1 wt.% Pt/Al2O3. For α-Fe2O3, a less expensive catalyst, a conversion of 61% for about 60 hours was obtained. [...]

Co doped ZnO semiconductor materials: structural, morphological and magnetic properties

64%

Popa A., Toloman D., Raita O., Biris A., Borodi G., Mustafa T., Watanabe F., Biris A., Darabont A., Giurgiu L.

Open Physics

2011

vol. 9

issue 6

1446-1451

Structural, morphological and magnetic properties of Zn1−xCoxO (x = 0.01 and 0.03) powdered materials are presented. XRD studies reveal a wurtzite-type structure, while the formation of a Co3O4 secondary phase was evidenced by Raman spectroscopy. A ferromagnetic behaviour with low Curie temperature was evidenced by Electron Paramagnetic Resonance (EPR) investigation. We suggest that the origin of the ferromagnetism in Zn1−xCoxO powders is probably due to the presence of the mixed cation valence of Co ions via a double-exchange mechanism rather than the real doping effect.

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2 Open Chemistry

1 Open Physics

1 2014

1 2012

1 2011

3 Borodi G.

1 Axente D.

1 Balla A.

1 Biris A.

1 Darabont A.

1 Giurgiu L.

1 Lazăr D.

1 Marcu C.

1 Mustafa T.

1 Popa A.

1 Raita O.

1 Silvestru C.

1 Toloman D.

1 Vlassa M.

1 Watanabe F.

Search results

Hydrogen bonding-based 3D supramolecular architecture of [Cu(CHA)2][TCM]·11H2O

Catalytic reduction of sulfuric acid to sulfur dioxide

Co doped ZnO semiconductor materials: structural, morphological and magnetic properties