{HEAD ~ The compound} may have the formula 2C L M R. The substructure {TAIL ~ L} may be selected from an optionally substituted propenylene group and trimethylene group  
{ HEAD ~ The compound } may have the formula 2C L M R. The substructure { TAIL ~ L } may be selected from an optionally substituted propenylene group and trimethylene group
HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH