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Titolo:
Spectroscopic study of the hydration equilibria and water exchange dynamics of lanthanide(III) complexes of 1,7-bis(carboxymethyl)-1,4,7,10-tetraazacyclododecane (DO2A)
Autore:
Yerly, F; Dunand, FA; Toth, E; Figueirinha, A; Kovacs, Z; Sherry, AD; Geraldes, CFGC; Merbach, AE;
Indirizzi:
Univ Coimbra, Fac Sci & Technol, Dept Biochem, P-3000 Coimbra, Portugal Univ Coimbra Coimbra Portugal P-3000 t Biochem, P-3000 Coimbra, Portugal Univ Lausanne, BCH, Inst Inorgan & Analyt Chem, CH-1015 Lausanne, Switzerland Univ Lausanne Lausanne Switzerland CH-1015 CH-1015 Lausanne, Switzerland Univ Coimbra, Ctr Neurosci, P-3000 Coimbra, Portugal Univ Coimbra Coimbra Portugal P-3000 Neurosci, P-3000 Coimbra, Portugal Univ Texas, Dept Chem, Richardson, TX 75083 USA Univ Texas Richardson TX USA 75083 s, Dept Chem, Richardson, TX 75083 USA Univ Texas, SW Med Ctr, Dept Radiol, Mary Nell & Ralph B Rogers Magnet Resonance Ctr, Dallas, TX 75235 USA Univ Texas Dallas TX USA 75235 Magnet Resonance Ctr, Dallas, TX 75235 USA
Titolo Testata:
EUROPEAN JOURNAL OF INORGANIC CHEMISTRY
fascicolo: 5, , anno: 2000,
pagine: 1001 - 1006
SICI:
1434-1948(200005):5<1001:SSOTHE>2.0.ZU;2-8
Fonte:
ISI
Lingua:
ENG
Soggetto:
MAGNETIC-RESONANCE SHIFTS; MACROCYCLIC COMPLEXES; CONTRAST AGENTS; LUMINESCENCE; LIGANDS; METAL; IONS; ELECTROPHORESIS; RELAXATION; PYRIDINE;
Keywords:
imaging agents; lanthanides; NMR spectroscopy; DNA cleavage;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Citazioni:
32
Recensione:
Indirizzi per estratti:
Indirizzo: Geraldes, CFGC Univ Coimbra, Fac Sci & Technol, Dept Biochem, Apartado 3126, P-3000 Coimbra, Portugal Univ Coimbra Apartado 3126 Coimbra Portugal P-3000 ortugal
Citazione:
F. Yerly et al., "Spectroscopic study of the hydration equilibria and water exchange dynamics of lanthanide(III) complexes of 1,7-bis(carboxymethyl)-1,4,7,10-tetraazacyclododecane (DO2A)", EUR J INORG, (5), 2000, pp. 1001-1006

Abstract

The hydration state of a series of [Ln(DO2A)(H2O)(n)](+) complexes in aqueous solution at pH = 6.4-7.0 was studied by measuring the lanthanide-induced O-17 shifts (LIS) of water [Ln includes elements from Ce to Yb; DO2A = 1,7-bis(carboxymethyl)-1,4,7, 10-tetraazacyclododecane]. Their contact contribution, obtained from Reilley plots, indicated a decrease in the inner-sphere water coordination number of the [Ln(DO2A)(H2O)(n)]+ complexes from n = 3 (Ce-Eu), to n = 2 (Tb-Yb). A temperature-dependent UV/Vis absorption study of the 578-582 nm F-7(0) --> D-5(0) transition band of [Eu(DO2A)(H2O)(n)](+) in aqueous solution showed that this complex is present in an equilibrium between eight- and nine-coordinate species with n = 2 and n = 3, respectively. The hydration equilibrium parameters (2 reversible arrow 3), K-2-3(298), 4.0 +/- 0.2, Delta H-2-3(0) = -12.1 +/- 1 kJ mol(-1) and Delta S-2-3(0) = -28.9 +/- 3 J mol-K-1, correspond to an average hydration number of 2.65-2.85 in the temperature range 273-363 K. A variable temperature, multiplefield O-17 NMR study combined with direct EPR measurements of the transverse electronic relaxation rates has been used to obtain the parameters characterizing water exchange, rotation and electronic relaxation, all influencing the proton relaxivity of [Gd(DO2A)(H2O)(2-3)](+). The small increase in the water exchange rate of [Gd(DO2A)(H2O)(2-3)](+) (k(ex)(298) = (10 +/- 5)x 10(6)s(-1)) relative to that of [Gd(DOTA)(H2O)](-) (4.8 x 10(6) s(-1)) is a consequence of an unfavorable interplay of charge and hydration equilibria. The value of tau(R)(298) = 40 +/- 1 ps is short, and the electronic relaxation rate (1/T-2e approximate to 1.2 x 10(10) s(-1)) is fast relative to [Gd(DOTA)(H2O)](-) (1.3-2.4 x 10(9) s(-1) for B = 0.34 T). These parameters negate to some extent the expected increase in proton relaxivity of the [Gd(DO2A)(H2O)(2-3)](+) complex.

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Documento generato il 28/11/20 alle ore 09:35:19