These compounds comprise a moiety which provides a detectable species when released from {HEAD ~ the compound} in {TAIL ~ an environment} of pH 9 or less  
in
These compounds comprise a moiety which provides a detectable species when released from { HEAD ~ the compound } in { TAIL ~ an environment } of pH 9 or less
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH