Circularly polarized luminescence/total luminescence and conductometric studies of lanthanide-chiral crown ether complexes in solution
The focus of this research was to elucidate the structure and stoichiometry of europium (III) and terbium (III) complexes of chiral 15-crown-5 and 18-crown-6 macrocycles dissolved in the solvents acetonitrile (MeCN), 2,2,2-trifluoroethanol (TFE), and 1,1,1,3,3,3-hexafluoroisopropanol (HFiP). The chiral 15-crown-5 ethers synthesized in this work are (2R,3R)-2,3-dimethyl-1,4,7,10,13-pentaoxacyclopentadecane (2,3-15c5) and its isomer (2S,6S)-2,6-dimethyl-1,4,7,10,13-pentaoxacyclopentadecane (2,6-15c5). The chiral 18-crown-6 ligands employed in this study are (2R,3R)-2,3-dimethyl-1,4,7,10,13,16-hexaoxacyclooctadecane (2,3-18c6), (2S,6S)-2,6-dimethyl-1,4,7,10,13,16-hexaoxacyclooctadecane (2,6-18c6), (2R,3R,11R,12R)-2,3,11,12-tetramethyl-1,4,7,10,13,16-hexaoxacyclooctadecane (2,3,11,12-18c6), and (2S,6S,11S,15S)-2,6,11,15-tetramethyl-1,4,7,10,13-16-hexaoxacyclooctadecane (2,6,11,15-18c6). As probes of the crown-lanthanide association, the techniques of circularly polarized luminescence (CPL) and total luminescence (TL), were employed. Changes in CPL/TL spectra and the simultaneously measured conductivity observed during a titration of Eu(NO/sub 3/)/sub 3/ dissolved in TFE with 2,6-15c5 indicate that the crown-lanthanide nitrate complex is of 1:1 stoichiometry. Complexes between the dimethyl 15-crown-5 ligands and Eu-(ClO/sub 4/)/sub 3/ and Tb(ClO/sub 4/)/sub 3/ adopt a structure similar to that of the nitrate compounds. In TFE, changes in the CPL/TL and conductivity observed during titrations of Eu(ClO/sub 4/)/sub 3/ and Tb(ClO/sub 4/)/sub 3/ with 2,6-15c5 support the formation of 1:2 (lanthanide:crown) sandwich compounds in the presence of an excess of the polyether.
- Research Organization:
- Duke Univ., Durham, NC (USA)
- OSTI ID:
- 6908821
- Resource Relation:
- Other Information: Thesis (Ph. D.)
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
EUROPIUM COMPLEXES
MOLECULAR STRUCTURE
TERBIUM COMPLEXES
CHEMICAL PREPARATION
ELECTRIC CONDUCTIVITY
ETHERS
LUMINESCENCE
SYNTHESIS
COMPLEXES
ELECTRICAL PROPERTIES
ORGANIC COMPOUNDS
ORGANIC OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
RARE EARTH COMPLEXES
400201* - Chemical & Physicochemical Properties