R11 is independently selected from {TAIL ~ the group} consisting of {HEAD ~ alkyl} and aryl; and 
R11 is independently selected from { TAIL ~ the group } consisting of { HEAD ~ alkyl } and aryl ; and
OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH