R11 and R12 are each, independently, hydrogen, alkyl of 1 6 carbon atoms, aralkyl of 7 10 carbon atoms, {HEAD ~ cycloalkyl} of {TAIL ~ 3 8 carbon atoms}, halogen, or trifluoromethyl 
of
R11 and R12 are each , independently , hydrogen , alkyl of 1 6 carbon atoms , aralkyl of 7 10 carbon atoms , { HEAD ~ cycloalkyl } of { TAIL ~ 3 8 carbon atoms } , halogen , or trifluoromethyl
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH