Nuclear magnetic resonance and potentiometric studies of the protonation scheme of a triaza triacetic macrocycle and its complexes with lanthanum and lutetium
Journal Article
·
· Inorg. Chem.; (United States)
The protonation constants of the macrocyclic ligand 1,4,7-triazacyclononane-N,N',N''-triacetic acid (NOTA) have been measured by potentiometry, and the protonation sequence of the various amino and carboxylate groups of NOTA has been studied in D/sub 2/O as a function of pD from the chemical shifts of the nonlabile protons. Shielding constants for protonation of the amino groups were determined in a NMR study of the triaza macrocyclic amine, its trimethylated analogue, and NOTA and compared with values reported for linear polyamino polycarboxylates and cyclic tetraaza tetracarboxylate ligands. The results indicate that two nitrogens of NOTA are protonated at higher pH than the carboxylate groups. The last nitrogen is protonated only at very low pH. The sequence of protonation of NOTA supports the formation of hydrogen bonds between two protonated nitrogens and the adjacent two nonprotonated carboxylates. The /sup 1/H and /sup 13/C spectra of the La(NOTA) and Lu(NOTA) species were studied as a function of pH and temperature. 33 references, 5 figures, 4 tables.
- Research Organization:
- Univ. of Coimbra, Portugal
- OSTI ID:
- 5895018
- Journal Information:
- Inorg. Chem.; (United States), Journal Name: Inorg. Chem.; (United States) Vol. 24:23; ISSN INOCA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEAR CHEMISTRY
400301 -- Organic Chemistry-- Chemical & Physicochemical Properties-- (-1987)
400702* -- Radiochemistry & Nuclear Chemistry-- Properties of Radioactive Materials
BARYONS
CHEMICAL REACTIONS
COMPLEXES
DATA
ELEMENTARY PARTICLES
EXPERIMENTAL DATA
FERMIONS
HADRONS
HYDROGEN TRANSFER
INFORMATION
LANTHANUM COMPLEXES
LIGANDS
LUTETIUM COMPLEXES
MAGNETIC RESONANCE
NMR SPECTRA
NUCLEAR MAGNETIC RESONANCE
NUCLEONS
NUMERICAL DATA
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PH VALUE
POTENTIOMETRY
PROTONS
RARE EARTH COMPLEXES
RESONANCE
SPECTRA
TEMPERATURE DEPENDENCE
TITRATION
38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEAR CHEMISTRY
400301 -- Organic Chemistry-- Chemical & Physicochemical Properties-- (-1987)
400702* -- Radiochemistry & Nuclear Chemistry-- Properties of Radioactive Materials
BARYONS
CHEMICAL REACTIONS
COMPLEXES
DATA
ELEMENTARY PARTICLES
EXPERIMENTAL DATA
FERMIONS
HADRONS
HYDROGEN TRANSFER
INFORMATION
LANTHANUM COMPLEXES
LIGANDS
LUTETIUM COMPLEXES
MAGNETIC RESONANCE
NMR SPECTRA
NUCLEAR MAGNETIC RESONANCE
NUCLEONS
NUMERICAL DATA
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PH VALUE
POTENTIOMETRY
PROTONS
RARE EARTH COMPLEXES
RESONANCE
SPECTRA
TEMPERATURE DEPENDENCE
TITRATION