Ioan Rosca

Highly luminescent europium and terbium complexes based on succinimide and N-hydroxysuccinimide

Abstract The preparation of two highly luminescent europium(III) and terbium(III) complexes with succinimide (SI) and N-hydroxysuccinimide (NHSI) were reported, which were further investigated through elemental chemical analysis, thermal analysis, FT-IR, powder X-ray diffraction, SEM and fluorescence spectroscopy. Data collected through these analysis revealed the formation of the Eu(III) and Tb(III) complexes with the above mentioned ligands at a metal to ligand (M:L) molar ratio of 1:3. Interesting conclusions regarding the efficient sensitization through the coordination site of the lanthanide luminescent centers were retained from the photoluminescent spectra investigation. Strong luminescence emission was observed in case of Eu(III)-SI and Tb(III)-NHSI complexes while the corresponding Eu(III)-NHSI and Tb(III)-SI complexes exhibited no photo luminescent properties. Newly obtained luminescent lanthanide complexes may be of particular interest for various applications in optoelectronics.

New coordination compounds of Cr(III) used in leather tanning

Some new coordination compounds of Cr(III) using as ligand N-hydroxy - succinimide, were obtained and studied. The combination ratio, central atom: ligand were 1:1; 1:2 and 1:3. The new complex compounds were studied using UV-Vis spectroscopy, conductance and pH measurements. The studies of obtaining and of stability of the new compounds were accomplished in aqueous solutions using methods characteristic for coordination compounds: conductance and pH measurements. The combination ratios and the stability constants were determined with methods characteristic for studies in solutions.

Studies of obtaining and stability in aqueous medium of new complex compounds of Ti(IV) and Zr(IV) used in ecological leather tanning

In this paper, the study of obtaining new coordination compounds of Ti(IV) and Zr(IV) using as ligand: D,L-β-iso-butyric acid, is presented. Also, the stability of these compounds in aqueous medium is studied. The studies of obtaining and of stability of the new compounds were accomplished in aqueous solutions using methods characteristic for coordination compounds: conductance and pH measurements. The combination ratios and the stability were determined with methods characteristic for studies in solutions. From experimental data resulted that the combination ratio of central metallic atoms with the ligand derived from D,L-β-iso-butyric acid was 1:2. From experimental data resulted that in strong acid and strong basic mediums, the coordination compounds could not be obtained. The optimal stability of the studied compounds is limited between 3-6, pH - values. This fact is in accordance with the conditions of using these compounds in ecological leather tanning. Of great importance is that these compounds were used with very good results in tanning processes of different types of leather. This fact evidenced that the ecological alternative of tanning is better than non-ecological tanning using chrome compounds. The importance of this paper consists in obtaining new coordination compounds that can be used in ecological leather tanning.

NITROUS OXIDE DECOMPOSITION OVER Fe-ZSM-5 CATALYSTS PREPARED BY DIFFERENT METHODS

Two different methods of preparation (solid state exchange and aqueous exchange) with two different iron precursors (ferrous chloride, respectively ferric oxalate) have been used to introduce iron species in the zeolite ZSM-5. A special attention was devoted to the aqueous exchange method. The catalysts thus prepared were tested for direct N2O decomposition. The results of catalytic tests show that the Fe-ZSM-5 catalyst prepared by aqueous exchange in ferric oxalate solutions is much more active than the one prepared by solid state exchange.

Aspects Regarding the Synthesis Mechanism and Kinetics of Some Co-Ordination Polymers

The paper presents some aspects regarding the kinetics and mechanisms of the reactions between the Fe(III) and Cr(III) acetylacetonates with phosphinic acids. The experimental data indicate that the mechanism of the studied reactions is an SN2.

Structural Considerations on Some Inorganic Polymers of Fe(III) with Phosphorus Containing Rings

The compounds were synthesised by the reactions between Fe(III) acetylacetonate with each of the following acids: diphenylphosphinic, diphenyltiophosphinic and diphenylditiophosphinic, diethylphosphinic, diethyltiophosphinic, diethylditiophosphinic. The studies were performed by means of Mössbauer, IR and ESR spectroscopy and X-ray diffraction.