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Titolo:
Thermodynamic and structural aspects of manganese(II) complexes with polyaminopolycarboxylic ligands based upon 1,4,7,10-tetraazacyclododecane (cyclen). Crystal structure of dimeric [MnL](2)center dot 2CH(3)OH containing thenew ligand 1,4,7,10-tetraazacyclododecane-1,4-diacetate
Autore:
Bianchi, A; Calabi, L; Giorgi, C; Losi, P; Mariani, P; Palano, D; Paoli, P; Rossi, P; Valtancoli, B;
Indirizzi:
Univ Florence, Dept Chem, I-50144 Florence, Italy Univ Florence FlorenceItaly I-50144 Dept Chem, I-50144 Florence, Italy Bracco SpA, Div Res & Dev, I-20134 Milan, Italy Bracco SpA Milan Italy I-20134 SpA, Div Res & Dev, I-20134 Milan, Italy Univ Florence, Dept Energet, Florence, Italy Univ Florence Florence Italy iv Florence, Dept Energet, Florence, Italy
Titolo Testata:
JOURNAL OF THE CHEMICAL SOCIETY-DALTON TRANSACTIONS
fascicolo: 6, , anno: 2001,
pagine: 917 - 922
SICI:
1472-7773(2001):6<917:TASAOM>2.0.ZU;2-9
Fonte:
ISI
Lingua:
ENG
Soggetto:
MACROCYCLIC POLYAMINO CARBOXYLATES; MRI CONTRAST AGENT; X-RAY STRUCTURE; LANTHANIDE COMPLEXES; METAL-COMPLEXES; MN-DPDP; GADOLINIUM(III) COMPLEXES; GD3+ COMPLEXES; SCHIFF-BASE; IN-VIVO;
Keywords:
macrocycles; pharmaceutical chemistry; stability constants; thermodynamics; manganese;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Citazioni:
66
Recensione:
Indirizzi per estratti:
Indirizzo: Bianchi, A Univ Florence, Dept Chem, Via Maragliano 75-77, I-50144 Florence, Italy Univ Florence Via Maragliano 75-77 Florence Italy I-50144 taly
Citazione:
A. Bianchi et al., "Thermodynamic and structural aspects of manganese(II) complexes with polyaminopolycarboxylic ligands based upon 1,4,7,10-tetraazacyclododecane (cyclen). Crystal structure of dimeric [MnL](2)center dot 2CH(3)OH containing thenew ligand 1,4,7,10-tetraazacyclododecane-1,4-diacetate", J CHEM S DA, (6), 2001, pp. 917-922

Abstract

The formation of manganese(II) complexes with polyaminopolycarboxylic ligands based upon 1,4,7,10-tetraazacyclododecane (cyclen) has been studied in aqueous solution by means of potentiometric and microcalorimetric techniques affording log K, DeltaH degrees and T DeltaS degrees values for the complexation reactions. The ML complexes present high stability constants, due to both favourable enthalpic and entropic contributions; with the unique exception of DOTA (1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid), the entropic term is prevalent. The new ligand 1,4-DO2A (1,4,7,10-tetraazacyclododecane-1,4-diacetic acid) forms a more stable complex than the 1,7-DO2A isomer. The thermodynamic results are discussed in terms of ligand characteristics: number and type of donor atoms, overall charge, substituent location. The crystal structure of [MnL](2). 2CH(3)OH (H2L=1,4-DO2A), obtainedby single crystal X-ray analysis, displays a centrosymmetric dimeric [Mn2L2] unit in which each manganese atom is seven-coordinated by four nitrogen atoms of a cyclen macrocycle, one oxygen atom of each of the acetate groupslinked to this macrocyclic unit, and one oxygen atom pertaining to an acetate group of the other cyclen molecule in the same dimeric unit and bridging the two metal centers. The resulting binuclear complex contains a doubly bridged bimetallic core with Mn . . . Mn distance of 3.537(1) Angstrom.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 21/09/20 alle ore 03:31:54