18815
The peroxo O - O bond is shown to gradually become more activated as the N - heterocyclic amines move closer to the metal ion causing a decrease in pi - donation from the peroxo pi v * ( O - O ) orbital .
 Chemical: peroxo O - O; Chemical: N - heterocyclic amines; Chemical: O - O
Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
Answer:
 Chemical: peroxo O - O; Chemical: N - heterocyclic amines; Chemical: O - O