9047
Given that energy ( exciton ) migration in natural photosynthesis primarily occurs in highly ordered porphyrin - like pigments ( chlorophylls ) , equally highly ordered porphyrin - based metal - organic frameworks ( MOFs ) might be expected to exhibit similar behavior , thereby facilitating antenna - like light - harvesting and positioning such materials for use in solar energy conversion schemes .
 porphyrin, chlorophylls, porphyrin
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: Chemical 
Text: {0} 
Answer:
 porphyrin, chlorophylls, porphyrin