EXAFS and EPR studies of inclusion compounds of the trans-[Cu(en)2(H2O)2]2+ in cucurbit[8]uril

Abstract

This work describes EXAFS and EPR studies of inclusion compounds of the trans-[Cu(en)2(H2O)2]2+ complex in the macrocyclic cavitand CB[8] at different stages of heat treatment in the hydrogen atmosphere in a temperature range of 200–330°C. The structure and composition of the nearest environment of copper atoms are characterized, and the interatomic distances and coordination numbers are determined. It is shown that the structure of the copper complex inside the cavitand CB[8] remains unchanged at the first stage of complex preparation and upon heating up to 280°C in hydrogen atmosphere. The copper environment corresponds to four nitrogen atoms and two oxygen atoms. Further temperature treatment at 330°C causes decomposition of the complex inside the cavitand without the formation of copper clusters.