A novel hexachelating amino-thiol ligand and its complex with gallium(III)
- Washington Univ. School of Medicine, St. Louis, MO (USA)
The ligand 1,4,7-tris(2-mercaptoethyl)-1,4,7-triazacyclononane, TS-TACNH{sub 3} (1), was synthesized from the parent amine, TACN, by reaction with ethylene sulfide in benzene. TS-TACNH{sub 3} undergoes reaction with Ga(NO{sub 3}){sub 3}{times}9H{sub 2}O in ethanol to give the neutral complex Ga(TS-TACN) (2). The complex may be recrystallized from dichloromethane as pale pink needles of the disolvate and the crystal structure is reported. There are four molecules of complex and two molecules of solvation (CH{sub 2}Cl{sub 2}) present per unit cell. The gallium is fully chelated in a slightly distorted octahedral environment by the three amine nitrogens and the three thiolate sulfurs. For comparison, the Ga{sup 3+} complex of the similarly hexachelating ligand 1,4,7-triazacyclononane-1,4,7-triacetic acid, NOTA, is also presented. The complex Ga(NOTA) (3), crystallizes from boiling water also as pale pink needles. Again, the metal center is fully chelated in a slightly distorted octahedral environment. The degree of distortion may be expressed as trigonal twist, {phi}, where {phi} = 0{degree} for a true octahedron and {phi} = 60{degree} for a trigonal prism. While both Ga(TS-TACN) and Ga(NOTA) are potentially isostructural, in regard to coordination geometry, with trigonal-prismatic Fe(NOTA) ({phi} = 34.8{degree}), the gallium(III) complexes are only slightly distorted from a regular octahedral coordination sphere (Ga(NOTA) {phi} = 12.4{degree} and Ga(TS-TACN) {phi} = 10.4{degree}). Preliminary results indicate {sup 68}Ga(TS-TACN) to be stable in vivo versus the blood protein transferrin, indicating a relatively high stability constant for this hexachelating ligand. 14 refs., 7 figs., 3 tabs.
- DOE Contract Number:
- FG02-87ER60512
- OSTI ID:
- 6944954
- Journal Information:
- Inorganic Chemistry; (USA), Journal Name: Inorganic Chemistry; (USA) Vol. 29:4; ISSN 0020-1669; ISSN INOCA
- Country of Publication:
- United States
- Language:
- English
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62 RADIOLOGY AND NUCLEAR MEDICINE
ALKANES
AMINES
BETA DECAY RADIOISOTOPES
BETA-PLUS DECAY RADIOISOTOPES
COMPLEXES
CRYSTAL STRUCTURE
CYCLOALKANES
DATA
DRUGS
EXPERIMENTAL DATA
GALLIUM 68
GALLIUM COMPLEXES
GALLIUM ISOTOPES
HOURS LIVING RADIOISOTOPES
HYDROCARBONS
INFORMATION
INTERMEDIATE MASS NUCLEI
ISOTOPES
LABELLED COMPOUNDS
NUCLEI
NUMERICAL DATA
ODD-ODD NUCLEI
ORGANIC COMPOUNDS
ORGANIC SULFUR COMPOUNDS
RADIOISOTOPES
RADIOPHARMACEUTICALS
SYNTHESIS