3574
The design of pyridyl - based fluorescent sensors for selective sensing of metal ions is examined in terms of the role of spin - orbit coupling constants ( zeta ) , paramagnetism , and steric effects in the development of selective fluorescent sensors that operate via chelation enhanced fluorescence ( CHEF ) .
 Chemical: pyridyl
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: pyridyl