O=C(Nc1ccc2ccccc2c1)[C@@H]1C[C@H]1[C@@H](NP(=O)(c1ccccc1)c1ccccc1)c1ccccc1
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?