and wherein {HEAD ~ T3} is {TAIL ~ a timing} or linking group which functions by electron transfer down a conjugated chain and is represented by the formula ##STR25## wherein *** denotes the point of attachment to E2 and **** denotes the point of attachment to PUG 
is
and wherein { HEAD ~ T3 } is { TAIL ~ a timing } or linking group which functions by electron transfer down a conjugated chain and is represented by the formula # # STR25 # # wherein * * * denotes the point of attachment to E2 and * * * * denotes the point of attachment to PUG
OTH OTH HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH