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