6533b85bfe1ef96bd12ba9cc

RESEARCH PRODUCT

Spectroscopic investigations of matrix effects induced by silicate xerogels prepared by the sol-gel method on the entrapped Cr(NCS) 6 3− ions

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Abstract Time- and temperature-resolved electronic absorption end emission spectra of silicate xerogels made via the sol-gel technique and doped with K 3 [Cr(NCS) 6 ] have been obtained. These results, along with excited states lifetime measurements, document an unexpected colour change of the entrapped chromium complex from violet to green. By varying the conditions of the doped xerogels preparation, it has been shown that the observed colour transition can not be attributed to ligand exchange with NH 3 or water molecules. On the other hand, the oxygen-rich network of silicate xerogels might be responsible for the observed behaviour. It has been shown that dimethylsulfoxide (DMSO), while destabilizing the Cr(NCS) 6 3− ion in liquid solutions, prevents its colour change in solid silicate xerogel matrices.