Bisphenol-C is the strongest bifunctional ERα-agonist and ERβ-antagonist due to magnified halogen bonding
Fig 9
Resonance structures feasible for BPC.
BPC is in a trans no-πbenzene ring-πC = C-nCl electron conjugation system. Resonance A shows the structures starting, at the top-left corner, from the n→π* transition of the chlorine atom 3p nonbonding orbital, whereas resonance B shows the structures starting from the n→π* transition of the oxygen atom 2p nonbonding orbital. R is another phenol group that is also involved in a similar trans no-πbenzene ring-πC = C-nCl electron conjugation. The resonance would take place also intersectingly in the cis arrangement.