Találati lista | Tudóstér

001-es BibID:	BIBFORM018852
Első szerző:	Tei, Lorenzo
Cím:	Mn(ii) complexes of novel hexadentate AAZTA-like chelators : a solution thermodynamics and relaxometric study / Lorenzo Tei, Giuseppe Gugliotta, Marianna Fekete, Ferenc K. Kálmán, Mauro Botta
Dátum:	2011
ISSN:	1477-9226
Megjegyzések:	Three novel chelators based on the 6-amino-6-methylperhydro-1,4-diazepine scaffold and possessing three pendant N-acetic or N-?-methylacetic acid have been synthesised. The ligands contain six donor atoms for complexation of MnII ions and thus potentially leave an additional site for coordination of a water molecule. The protonation constants of the ligands and the stability constants of their complexes formed with MnII ion were determined by pH-potentiometric titrations in 0.15 M NaCl solution at 25 ?C and compared to those of the parent AAZTA ligand (AAZTA = 6-amino-6-methylperhydro-1,4-diazepine tetraacetic acid). In spite of the similar value of the total basicity (?log K), the values of the stability constants of the MnIIAAZTA-like complexes are more than three orders of magnitude lower than that of MnAAZTA (log KMnL = 14.19). A detailed 1H and 17O NMR relaxometric study was carried out on the MnII complexes in aqueous solution as a function of pH, temperature and magnetic field strength. The 1H NMRD profiles of all the complexes show a similar shape, typical of low-molecular weight systems, but amplitudes that markedly differ to indicate a different degree of hydration. A similar behaviour is shown by the 17O NMR transverse relaxation rates and chemical shift data as a function of temperature. The experimental data can be rationalised by considering the presence in solution of a mixture of two isomeric species differing in coordination number (7 and 6) and in the number (1 and 0) of bound water molecules. Whereas this type of coordination equilibrium has been previously reported for lanthanide(III) complexes, it is observed for the first time on MnII chelates.
Tárgyszavak:	Természettudományok Kémiai tudományok idegen nyelvű folyóiratközlemény külföldi lapban
Megjelenés:	Dalton Transactions. - 40 : 9 (2011), p. 2025-2032. -
További szerzők:	Gugliotta, Giuseppe Fekete Marianna Kálmán Ferenc K. (1978-) (vegyész) Botta, Mauro
Pályázati támogatás:	ESF COST Action D38 Egyéb
Internet cím:	DOI Intézményi repozitóriumban (DEA) tárolt változat
Borító:
Saját polcon: