12168
The absorption band of this quinoidal thiophene dye appeared at longer wavelengths than those of dyes with similar pi - conjugation length , indicating the effective pi - conjugation through the quinoidal structure .
 Chemical: quinoidal thiophene
Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: Chemical 
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Answer:
 Chemical: quinoidal thiophene