1500
A crown - ether dithiol quaterthiophene is synthesized and immobilized on gold surface by double covalent fixation .
 Chemical: crown - ether dithiol quaterthiophene
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 dithiol quaterthiophene