R6, R8, R12, and R13 are independently selected from {HEAD ~ the group} consisting of {TAIL ~ hydrogen}, alkyl, alkoxyalkyl, polyfluoroalkyl, hydroxyalkyl, polyhydroxyalkyl, aralkyl, R9, —R15 and —R9 
consisting of
R6 , R8 , R12 , and R13 are independently selected from { HEAD ~ the group } consisting of { TAIL ~ hydrogen } , alkyl , alkoxyalkyl , polyfluoroalkyl , hydroxyalkyl , polyhydroxyalkyl , aralkyl , R9 , — R15 and — R9
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL REL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH