8143
In contrast , the use of halogen bonding to trigger supramolecular gel formation in a two - component gel ( ' co - gel ' ) is essentially unexplored , and forms the basis for this study .
 Chemical: halogen
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: halogen