Micro FT-IR and EXAFS spectroscopy methods were utilized to characteri
ze the periodic and chaotic precipitation occuring in some metal bile
salt systems in sol-gel medium. The results indicate that the precipit
ates were just the corresponding metal bile salt complexes, and the ag
ar gel medium has very weak interaction with the dispersed ions. In ad
dition, comparison between the EXAFS spectra of the precipitate formed
in the CoCl2-NaDC gel system and of the complexes Co(DC)(2) synthesiz
ed in water-ethanol solvent suggested that the two complexes were of s
imilar composition but the precipitate in the gel had a more ordered c
oordination structure.