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Titolo:
ALKALINE-EARTH METAL AND LANTHANIDE(III) COMPLEXES OF LIGANDS BASED UPON 1,4,7,10-TETRAAZACYCLODODECANE-1,7-BIS(ACETIC ACID)
Autore:
HUSKENS J; TORRES DA; KOVACS Z; ANDRE JP; GERALDES CFGC; SHERRY AD;
Indirizzi:
UNIV TEXAS,DEPT CHEM,POB 830688 RICHARDSON TX 75083 UNIV TEXAS,DEPT CHEM RICHARDSON TX 75083 UNIV MINHO,SCH SCI,DEPT CHEM P-4714 BRAGA PORTUGAL UNIV COIMBRA,FAC SCI & TECHNOL,DEPT BIOCHEM P-3000 COIMBRA PORTUGAL UNIV COIMBRA,FAC SCI & TECHNOL,CTR NEUROSCI P-3000 COIMBRA PORTUGAL UNIV TEXAS,SW MED CTR,DEPT RADIOL,ROGERS MAGNET RESONANCE CTR DALLAS TX 75235
Titolo Testata:
Inorganic chemistry
fascicolo: 7, volume: 36, anno: 1997,
pagine: 1495 - 1503
SICI:
0020-1669(1997)36:7<1495:AMALCO>2.0.ZU;2-F
Fonte:
ISI
Lingua:
ENG
Soggetto:
NUCLEAR MAGNETIC-RESONANCE; AZATETRA-ACETIC ACIDS; GADOLINIUM(III) COMPLEXES; EXPLORATORY CALCULATIONS; PROTONATION SEQUENCE; AMINO CARBOXYLATES; HYDRATION NUMBERS; AQUEOUS-SOLUTION; CONTRAST AGENTS; PH-DEPENDENCE;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
61
Recensione:
Indirizzi per estratti:
Citazione:
J. Huskens et al., "ALKALINE-EARTH METAL AND LANTHANIDE(III) COMPLEXES OF LIGANDS BASED UPON 1,4,7,10-TETRAAZACYCLODODECANE-1,7-BIS(ACETIC ACID)", Inorganic chemistry, 36(7), 1997, pp. 1495-1503

Abstract

The macrocyclic ligand DO2A (1,4,7,10-tetraazacyclododecane-1,7-bis(acetic acid)) was prepared and used as a building block for four new macrocyclic ligands having mixed side-chain chelating groups. These ligands and their complexes with Mg-II, Ca-II, and Ln(III) were studied extensively by potentiometry, high-resolution NMR, and water proton relaxivity measurements. The protonation constants of all compounds compared well with those of other cyclen-based macrocyclic ligands. All Ca-II complexes were found to be more stable than the corresponding Mg-II complexes. Trends for the stabilities of the Ln(III) complexes are discussed and compared with literature data, incorporating the effects ofwater coordination numbers, Ln(III) contraction, and the nature of the side chains and the steric hindrance between them. H-1 NMR titrations of DO2A revealed that the first and second protonations take place preferentially at the secondary ring nitrogens, while the third and fourth involved protonation of the acetates. O-17 NMR shifts showed that the DyDO2A(+) complex had two inner-sphere water molecules. Water proton spin-lattice relaxation rates for the GdDO2A(+) complex were also consistent with water exchange between bulk water and two inner-sphere Gd-III coordination positions. Upon formation of the diamagnetic complexes of DO2A (Ca-II, Mg-II, La-III, and Lu-III), all of the macrocyclic ring protons became nonequivalent due to slow conformational rearrangements, while the signals for the acetate CH2 protons remained a singlet.

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Documento generato il 24/11/20 alle ore 14:20:58