Gallium and indium imaging agents. 2. Complexes of sulfonated catecholyamide sequestering agents
The solution equilibria for the reaction of Ga(III) and In(III) with the hexadentate ligands N, N', N''-tris(2,3-dihydroxy-5-sulfonatobenzoyl)-1,3,5-tris(aminomethyl)benzene (MECAMS) and N, N', N''-tris(2,3-dihydroxy-5-sulfonatobenzoyl)-1,5,10-triazadecane (3,4-LICAMS) and the bidentate catechol N,N-dimethyl-2,3-dihydroxy-5-sulfonatobenzamide (DMBS) have been determined on 0.1 M KNO/sub 3/ at 25/sup 0/C. Both Ga(III) and In(III) are coordinated by three catecholate groups at high pH and have formation constants of the order ..beta../sub 110/ = 10/sup 38/ M/sup -1/. As the acidity of the medium is increased, the metal complexes of the hexadentate sequestering agents undergo protonation reactions. For the determination of the nature of the protonated metal chelates, the stretching frequency of the amide carbonyl has been monitored in D/sub 2/O by Fourier transform infrared spectroscopy (FT IR). These data support a series of two one-proton steps to form a mixed salicylate-catecholate coordination about the metal ion. In the salicylate bonding mode the metal is bound through the ortho phenolic oxygen and the amide cabonyl whereas catecholate coordination is via the adjacent phenols. In contrast, protonation of the M/sup III/(DMBS)/sub 3/ complexes results in dissociation of a catechol moiety to form M/sup III/(DMBS)/sub 2/. The potential use of these compounds as tumor-imaging agents in cancer diagnosis is discussed, with specific attention to the role of the gallium transferrin complex.
- Research Organization:
- Univ. of California, Berkeley
- OSTI ID:
- 7065713
- Journal Information:
- Inorg. Chem.; (United States), Vol. 21:6
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
62 RADIOLOGY AND NUCLEAR MEDICINE
GALLIUM
EXTRACTION
INDIUM
ORGANIC SULFUR COMPOUNDS
POTENTIOMETRY
STABILITY
AMIDES
CHELATES
DATA
EQUATIONS
EXPERIMENTAL DATA
INFRARED SPECTRA
IRON
LIGANDS
MEDIUM TEMPERATURE
PH VALUE
PYROCATECHOL
RADIONUCLIDE KINETICS
AROMATICS
COMPLEXES
DEVELOPERS
ELEMENTS
HYDROXY COMPOUNDS
INFORMATION
METALS
NUMERICAL DATA
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PHENOLS
POLYPHENOLS
SEPARATION PROCESSES
SPECTRA
TITRATION
TRANSITION ELEMENTS
560161* - Radionuclide Effects
Kinetics
& Toxicology- Man
550601 - Medicine- Unsealed Radionuclides in Diagnostics