Krystyna Bukietyńska

Spectroscopy and structures of neodymium solvates in high dielectric constant solvents

The electronic spectra of neodymium nitrate in mono- and disubstituted amides were investigated. The transitions were identified and the oscillator strengths of the 4ƒ−4ƒ transitions were determined. The τλ parameters were evaluated from the Judd equation and good agreement between Pexp and Pcalc was found. From the spectroscopic data, ultrasonic absorption and conductivities, low-symmetry inner-sphere [NdNO3(DMF)(x−1)]2+ species were found to be formed in the disubstituted amides.

Complexes of vanadium(III) with l-alanine and l-aspartic acid

The equilibria of the complexation processes of V(3+) with L-alanine and L-aspartic acid in aqueous solution over a wide pH range (2-10) were studied by potentiometric and spectroscopic (UV-Vis, CD) methods. The results show that alanine forms complexes with V(3+) in the metal ion concentration range and at the ligand-to-metal ratios investigated, giving mononuclear species only. In ML(2) species, which dominate in the range pH 4-8, alanine acts as a bidendate ligand through O and N atoms. The complexation processes of V(3+) with aspartic acid are more complicated. In acidic solution (up to pH approximately 4) they are similar to those for alanine. In the higher pH region, however, there are complicated equilibria among mono- and various dinuclear species. These dinuclear species consist of carboxylic or mu-oxo bridges and differ from each other by the number of coordinated ligands and OH(-) groups. The solid phase of the V(III) complex with aspartic acid could be isolated from nonaqueous solution only. Spectroscopic (UV-Vis-IR) measurements and magnetic susceptibility data confirm the coordination of vanadium(III) by two carboxylic groups. Both V(III)-L-aspartic acid and V(III)-L-alanine complexes have a significant apoptotic effect on Hepatoma Morris 5123 cells.

Spectroscopy and structure of neodymium complexes with EDTA

Abstract The spectral properties of Nd 3+ -EDTA solutions were investigated at different Nd 3+ and EDTA concentrations within a broad pH region. The analysis of the oscillator strength values of the ‘hypersensitive’ 2 G 7/2 , 4 G 5/2 ← 4 I 9/2 transition and of the Judd- Ofelt intensity parameters was performed in order to investigate the formation and the type of bonding in the Nd 3+ -EDTA species. The correlation of these results with NMR and kinetic data has made it possible to suggest a relatively complete model of the Nd 3+ -EDTA coordination. The X-ray data in the solid phase confirmed the proposed model.

Spectroscopic properties of Nd3+ complexes with 2,2'-dipyridine and 1,10-phenanthroline

Abstract Absorption spectroscopy studies of the hydrated and anhydrous Nd 3+ perchlorates in CH 3 OH with different concentrations of N-donor ligands 2,2′- dipyridine (Dipy) and 1,10-phenanthroline (Phe) are presented in this paper. Solid complexes of neodymium perchlorate with Dipy and Phe were also isolated. Analysis of the intensities of ff transitions expressed in terms of oscillator strengths and Judd- Ofelt parameters τλ indicate that the electron spectroscopy method can be successfully applied to the investigation of Ln 3+ ion coordination processes in nonaqueous solvents with N-donor ligands. It was proved that Dipy is a significantly weaker ligand than Phe for Nd 3+ ion. Most stable species of Nd 3+ Phe complexes which exist in solution are species with 2 and 4 Phe molecules.

Spectroscopy and structure of heavy lanthanide complexes with EDTA

Abstract The electronic absorption method has been used to study the equilibria and structure of Ho 3+ and Er 3+ complexes with EDTA. Spectral properties of these systems are investigated for different Ln 3+ concentrations at M:L ratios of 1:1 and 1:2 within a broad pH range. Analysis of the ‘hypersensitive’ transition band shapes and intensities and of the Judd–Ofelt intensity parameters τ λ allows us to investigate the formation and the type of bonding of Ln 3+ –EDTA species occurring in solution. Comparison of the results for Ho 3+ and Er 3+ with Nd 3+ –EDTA [1] complexes shows a significant difference between EDTA complexes of heavy and light lanthanides.

f–f Transition intensities of europium(III) acetate complexes in a single crystal and in solution

Abstract Optical absorption spectra of Eu III -acetate complexes in a single crystal and in solution as well as of the Eu III -aquoion were analyzed. With decreasing temperature from 293 to 4 K an unusually strong intensity decrease of the 7 F 0 → 5 D 2 , 7 F 0 → 5 D 1 and 7 F 0 → 5 D 0 transitions in the crystal was detected. A distinct influence of light polarization on these transitions caused by crystal anisotropy was observed. Spectral intensities of the investigated systems were parametrized in terms of the Judd–Ofelt theory.

The spectroscopy and structure of some lanthanide chlorides in amide solutions

The spectral properties of Pr, Nd, Ho and Er anhydrous and hydrated chlorides in amide solutions have been investigated. The Judd—Oefelt method of intensity analysis and determination of nepheloauxetic effect allowed to establish the first coordination sphere of lanthanide ion and approximate symmetry of amide solvates of anhydrous and hydrated lanthanide chlorides. The difference between symmetry and coordination numbers of light and heavy lanthanide solvates has been found. The relation between the structure of lanthanide solvates and structure of amide molecules have been established.

Spectroscopy of heavy lanthanide complexes with NTA

Abstract Spectroscopic properties of Ho 3+ -NTA and Er 3+ -NTA systems were investigated for different M:L ratios and different concentrations of M within a broad pH range. Analysis of the oscillator strength values of the ‘hypersensitive’ transitions and of the Judd–Ofelt intensity parameters τ λ allowed us to investigate the formation and the type of bonding of the Ln 3+ –NTA species occurring in solution. These results are in good agreement with the results of luminescence measurements.

Distortion of the decavanadate polyhedron and the role of hydrogen bonding in dimethylammonium decavanadate

The dimethylammonium decavanadate, [Me2NH2]6[V10O28] · H2O was synthesized and its crystal structure determined by X-ray diffraction. I.r. and n.i.r. spectra were also recorded. The results, compared to the reported crystal structures of decavanadates, indicate that the deformations of isolated polyhedra and their crystal lattice packing are closely related to the anion interactions both with cations and/or water (or solvent) molecules. The i.r. spectra of the relatively strongly distorted (but unprotonated) decavanadate anion are very similar to the spectrum of protonated [Me3CNH3]4[H2V10O28] [1], with a different distribution of hydrogen bonds. Thus the i.r. spectra of the decavanadate salts provide no evidence for protonation. In each case, the analysis of a particular decavanadate spectrum by advanced quantum chemistry calculations is needed. The near i.r. spectra of [Me2NH2]6[V10O28] · H2O can be helpful in gaining a better understanding of decavanadate salts structures. These results are important because of the role of decavanadate in catalysis.

Spectral intensity analysis of the S3+-POCl3-ZrCl4 system

Abstract The solution absorption spectra of the Sm3+-POCl3-ZrCl4 system were recorded within the 40,000-4000 cm−1 range. A number of absorption bands in solution in the near-IR region were considered taking advantage of the optical transparency of the solvent. It was proved that only in this case the Judd-Ofelt parameters ωλ are physically significant and can be determined with relatively good accuracy.