Coordination environment of copper (II) during the sol–gel process of an aminated alkoxide

Abstract

Copper(II) complexes with N-2-aminoethyl-3-aminopropyltnmethoxysilane (N – N) as an ethylenediamme analogue were analysed prior to the sol–gel process, during the reaction (N – N + tetramethoxysilane) with water and in the gel products, to determine the coordination environment of the central ion. The results of EPR, thermal decomposition and Cu^II adsorption studies are summarized in three identified models of the coordination sites in the gels. Partial conversion of the bis- to mono-[N – N] environment of Cu^II during the transition from the sol to the gel is observed. There is also EPR evidence of the existence of another copper(II) site, the coordination sphere of which was not identified.