18814
The N - heterocyclic amines and ligand backbone ( Et vs Pr ) are found to modulate structural and reactivity properties , and O - O bond activation is shown , both experimentally and theoretically , to track with metal ion Lewis acidity .
 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: N - heterocyclic amines; Chemical: O - O