ISSN:
1434-193X
Keywords:
Fluorine
;
Cryptands
;
Macrocycles
;
Macrocyclic ligands
;
Cyclophanes
;
Chemistry
;
General Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
---Novel fluorine-containing macrocyclic molecules have been synthesized in order to clarify the interaction or coordination ability of the C-F unit towards metal ions. The cage compounds 1 and 2 were prepared by direct coupling reactions between the appropriate diamines and dibromides, while bond isomers of the cage compounds were synthesized via fluorinated diaza[3.3]metacyclophanes. Complex formation with alkali metal cations, NH4+, and Ag+ ions has been assessed by picrate extraction experiments. Comparison of the cation affinities of hosts 1, 2, and 4, shows that the spatial arrangement of the fluorine atoms strongly affects the donor ability of the host molecules. The hexafluoro cage compound 1, with six fluorine atoms in an octahedral geometry, exhibits relatively strong coordination ability towards K+, NH4+, and Ag+ ions, while compound 2, with four fluorine atoms in a structure similar to that of 1 shows only poor affinity for these ions. Compound 4, which has six fluorine atoms arranged in a quasi planar fashion, was found to show weak affinity towards NH4+ and Ag+ ions. Thus, octahedrally arranged fluorine atoms evidently provide the best fit for spherical cations. Compound 1 shows characteristic 1H-, 13C-, and 19F-NMR-spectral changes upon complexation. The crystal structure of 1 has been elucidated and compared to that of the K+ complex. The C-F bonds are found to be slightly elongated in the K+ complex, which is clearly indicative of coordination of the fluorine atom to K+.Supporting information for this article is available on the WWW under //http://www.wiley-vch.de/contents/jc_2046/2000/99243_s.pdf or from the author.
Additional Material:
4 Ill.
Type of Medium:
Electronic Resource
Permalink
