O=C1C2C3C=C4c5ccccc5N(c5ccccc5)C4(C2C(=O)N1c1ccccc1)C1C(=O)N(c2ccccc2)C(=O)C31
Hydrogen bond acceptor: The atom, ion, or molecule component of a hydrogen bond which does not supply the bridging (shared) hydrogen atom. How many hydrogen bond acceptors does the molecule have?