O=[N+]([O-])O.c1ccc(CN[C@H]2C[C@@H](NCc3ccccn3)C[C@@H](NCc3ccccn3)C2)nc1
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?