{HEAD ~ The compound} 11, wherein Z1 and {TAIL ~ Z2} are each independently a single bond or alkylene 
wherein
{ HEAD ~ The compound } 11 , wherein Z1 and { TAIL ~ Z2 } are each independently a single bond or alkylene
HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH REL OTH OTH TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH