{HEAD ~ Aryl groups} can be substituted with {TAIL ~ up to four independently selected R12 groups}, as described herein 
substituted with
{ HEAD ~ Aryl groups } can be substituted with { TAIL ~ up to four independently selected R12 groups } , as described herein
HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH