1499
A crown - ether loop - derivatized oligothiophene doubly attached on gold surface as cation - binding switchable molecular junction .
 Chemical: crown - ether; Chemical: oligothiophene
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: crown - ether; Chemical: oligothiophene