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Titolo:
DINUCLEAR COPPER(II) COMPLEXES WITH CARBOXYLATE-RICH COORDINATION ENVIRONMENTS - MODELS FOR SUBSTITUTED COPPER(II) AMINOPEPTIDASES
Autore:
HOLZ RC; BRINK JM; GOBENA FT; OCONNOR CJ;
Indirizzi:
UTAH STATE UNIV,DEPT CHEM & BIOCHEM LOGAN UT 84322 UNIV NEW ORLEANS,DEPT CHEM NEW ORLEANS LA 70122
Titolo Testata:
Inorganic chemistry
fascicolo: 26, volume: 33, anno: 1994,
pagine: 6086 - 6092
SICI:
0020-1669(1994)33:26<6086:DCCWCC>2.0.ZU;2-O
Fonte:
ISI
Lingua:
ENG
Soggetto:
LEUCINE AMINOPEPTIDASE; CRYSTAL-STRUCTURES; AEROMONAS AMINOPEPTIDASE; MAGNETIC-PROPERTIES; BOVINE LENS; BINUCLEAR; PROTEINS; LIGAND; ION; UTEROFERRIN;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
45
Recensione:
Indirizzi per estratti:
Citazione:
R.C. Holz et al., "DINUCLEAR COPPER(II) COMPLEXES WITH CARBOXYLATE-RICH COORDINATION ENVIRONMENTS - MODELS FOR SUBSTITUTED COPPER(II) AMINOPEPTIDASES", Inorganic chemistry, 33(26), 1994, pp. 6086-6092

Abstract

The dinucleating ligand -5-methyl-1,3-xylylene)bis(N-carboxymethylglycine) (CH(3)HXTA) has been used to synthesize the dinuclear Cu(II) diaqua complex [Cu-2(CH(3)HXTA)(H2O)(2)]H.4H(2)O (I): monoclinic space group P2(1)/n (a = 15.092(3) Angstrom, b = 10.842(3) Angstrom, c = 15.219(4) Angstrom, and beta = 104.70(2)degrees). The structure shows two distinct square pyramidal Cu(II) centers with each Cu(II) ion bound to two carboxylate oxygen atoms, one amine nitrogen atom, the phenolate oxygen atom, and one water oxygen atom. The Cu- -Cu separation is 3.726Angstrom and Cu1-O1-Cu2 angle is 127.9 degrees. The phenyl ring of the CH(3)HXTA ligand is twisted relative to the Cu1-O1-Cu2 plane and theresulting dihedral angle is 46.7 degrees. The electronic absorption and EPR spectra of 1 in aqueous solution at pH 3 suggest a shift towardtrigonal bipyramidal Cu(II) coordination in solution. Variable temperature magnetic susceptibility data for 1 indicates that it behaves as a simple Curie-Weiss paramagnet and hence the Cu(II) ions show little coupling (J-O). Titration of 1 with sodium hydroxide is accompanied bya reversible shift in the phenoxide-to-copper LMCT band at 420 nm anda concomitant decrease in the molar absorptivity. These data suggest that 1, is converted to a second dicopper(II) complex (2) with an apparent pK(a) of 8. The structure of 2, derived from electronic absorption, EPR, NMR, and Evans susceptibility measurements, indicate it is the(mu-phenoxo)Cu-hydroxo)dicopper(II) complex [Cu-2(CH(3)HXTA)(mu-OH)](2-).

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Documento generato il 01/12/20 alle ore 19:49:45