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  • 1
    Digitale Medien
    Digitale Medien
    Springer
    Journal of solution chemistry 26 (1997), S. 105-112 
    ISSN: 1572-8927
    Schlagwort(e): Neodymium complexation ; glutamic acid complex ; aspartic acid complex ; phenanthroline ternary complexes
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract Complexation of neodymium(III)-glutamate(glu)-phenanthroline(phen), neodymium(III)-aspartate(asp)-phenanthroline(phen) ternary systems and the corresponding binary systems in aqueous solution are discussed at various values of pH. Based on change regularity of hypersensitive transition intensities, the neodymium(III)-aspartate-phenanthroline ternary complex has a general formula of Nd(asp)3phen, but the composition of the complex of Nd(III) with glutamate and phenanthroline is complicated and has not been determined. The electronic spectra of these complexes were studied, Slater-Condon parametersF k s and the Lande parameter ξ4f were obtained. The rms deviation between calculated and observed energy levels is less than 43 cm−1. Bonding in these complexes are also investigated and bonding parameters calculated. The results show that Nd(III) and amino acids form complexes by ionic linkage with carboxylic oxygens, but with some weak covalency. Besides, the degrees of covalency in ternary complexes are larger than those in binary complexes.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    Springer
    Journal of solution chemistry 26 (1997), S. 105-112 
    ISSN: 1572-8927
    Schlagwort(e): Neodymium Complexation ; glutamic acid complex ; aspartic acid complex ; phenanthroline ternary complexes
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract Complexation of neodymium(III)–glutamate(glu)–phenanthroline(phen), neodymium(III)–aspartate(asp)–phenamhroline(phen) ternary systems and the corresponding binary systems in aqueous solution are discussed at various values of pH. Based on change regularity of hypersensitive transition intensities, the neodymium(III)–aspartate–phenanthroline ternary complex has a general formula of Nd(asp)3phen, but the composition of the complex of Nd(III) with glutamate and phenanthroline is complicated and has not been determined. The electronic spectra of these complexes were studied, Slater-Condon parameters Fks and the Lande parameter ξ 4f were obtained. The rms deviation between calculated and observed energy levels is less than 43 cm−1. Bonding in these complexes are also investigated and bonding parameters calculated. The results show that Nd(III) and amino acids form complexes by ionic linkage with carboxylic oxygens, but with some weak covalency. Besides, the degrees of covalency in ternary complexes are larger than those in binary complexes.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 43 (1994), S. 439-445 
    ISSN: 0006-3592
    Schlagwort(e): extraction from whole broth ; aqueous two-phase partition ; separation ; cephalosporin C ; desacetyl cephalosporin C ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Cephalosporin C was extracted from diluted or whole broth by PEG/salt aqueous two-phase systems. Parameters such as PEG molecular weight, salt type, pH, and salt concentration were investigated for finding a suitable extraction system. In PEG 600/ammonium sulfate or phosphate systems, Kc (partition coefficienct of cephalosporin C) was observed to be larger than 1, with Kd (partition coefficient of desacetyl cephalosporin C) being smaller than 1. The particular values of these coefficients would imply that the difficult separation of cephalosporin C and desacetyl cephalosporin C could possibly be achieved via the aqueous two-phase extraction. The addition of surfactants, water-miscible solvents, and neutral salts for enhancement of the separation efficiency was also investigated. The addition of surfactants to the system did not affect the separation efficiency substantially. Kc would increase whereas Kd decreased as a result of the addition of acetone, MeOH, EtOH, IPA, and n-BuOH. Meanwhile both Kc and Kd would decrease whenever neutral salts, NaCl, KCl, Kl, or KSCN, were added. The partitioning behavior of cephalosporin C and desacetyl cephalosporin C in filtered, whole, and different batches of broth was notably quite similar to that of diluted broth. The recovery yield of cephalosporin C in whole broth extraction was observed to be a function of centrifugal force used in phase separation. © 1994 John Wiley & Sons, Inc.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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