[en] The preparations of several hydrogenlanthanum(III) bis(porphyrinates) LaH(P)₂ [P = both OEP, TPP, or TBPP, or one OEP and one TPP, respectively], of some of their 'salts' of the π radicals La(P)₂, of the dilanthanum(III) trisporphyrinates La₂(OEP)₃ and La₂(OEP)₂(TPP), and of the π-diradical cation salt [Y(OEP)₂][Sbl₆] are described. The compounds are characterized by UV/Vis-, IR-, ¹H-NMR, ESR and mass spectra. The synthesis of lanthanoid porphyrins via the acetylacetonate method is discussed in general

[en] Short communication

No abstract available

No abstract available

[en] The protonation constants of L-alanine and the complex formation constants of its La(III) complexes were determined by potentiometric studies at ionic strengths 0.06, 0.1, and 0.15 mol dm^-3 (NaClO₄) and at different temperatures 20, 27, and 35^OC. The data together with the derived thermodynamic parameters ΔH^O, ΔS^O, and ΔG^O are reported and discussed. (author)

[en] The stoichiometric stability constants for La(III) and Y(III) L-serine complexes were determined by potentiometric methods at different ionic strenghts adjusted with NaClO₄ and at different temperatures. The overall changes in free energy (ΔG^O), enthalpy (ΔH^O), and entropy (ΔS^O) during the protonation of L-serine and that accompanying the complex formation with the metal ions have been evaluated. (author)

[en] In this communication, we have used theoretical calculations in order to prepare a composite with an enhanced magnetocaloric effect from La_0.4Re_0.1Ca_0.5MnO₃ (Re = Dy, Gd, and Eu) samples. Although the obtained composites did not exhibit very important values of magnetic entropy change (− ΔS), they are active in a very wide temperature range. One of the composites is characterized by a plateau-like shape of − ΔS(T) curves. Several anomalies were found in the magnetic and the magnetocaloric properties of our composites. The origin of these anomalies is essentially attributed to the phase separation phenomenon characterizing all the La_0.4Re_0.1Ca_0.5MnO₃ samples.

[en] The complex formation between La(III) and Eriochrome Cyanine R has been investigated. Three complexes have been detected. A first one (Complex I) in the pH range of 5.3-5.5 with lambda sub(max) = 460nm. a second one (Complex II) in the pH range of 6.2-6.5 with lambda sub(max) = 490nm and a third one (complex III) in the pH range of 8.2 - 9.0 with lambda sub(max) = 545nm and a shoulder between 570-580nm. The composition and stability constants of the complexes, respectively: complex I: La(ECR)₂ and 4.9 x 10⁷, complex II: La(ECR)₂ and 7.0 x 10⁷, complex III: La.ECR and 1.0 x 10⁴. All measurements were taken at 25.0 +- 0.1⁰C and μ = 0.2 (NaClO₄). (Author)

[en] Solvated tris-complexes of (R)- and (S)-1,1'-binaphthyl-2,2'-dyil phosphate with lanthanum(III) and europium(III) centers were prepared and characterized by spectroscopic methods and elemental analysis. Circularly polarized luminescence (CPL) spectra for the optically active isomers of the europium complexes are also reported

[en] The coordination chemistry of the lanthanides (ln) and actinides (An) in lower oxidation states is discussed, including the hydration-solvation properties of Ln²⁺ and An²⁺ in aqueous and aqueous-ethanolic solutions and the formation of complexes with the tetraphenylborate ion and crown ethers. Some physicochemical properties of a number of novel compounds with crown ethers are reported. In this paper the difference in the properties of Ln²⁺ and An²⁺ with an fⁿd⁰ and f^n-1d¹ configuration and the ability of the f^n-1 d¹ compounds to form mixed condensed clusters with Gd₂Cl₃ are discussed. The properties of Ln and An elements in various oxidation states are compared with those of elements of other groups in the periodic table