O=[N+]([O-])c1ccc2c(c1)N=C1O[C@H](c3ccc([C@H]4OC5=Nc6cc([N+](=O)[O-])ccc6NC5=C4O)cc3)C(O)=C1N2
Hydrogen bond acceptor is the chemical compound which contains the lone electron pairs that participate in the hydrogen bond formation. This compound should contain a more electronegative atom (more electronegative than hydrogen) with lone electron pairs. Then it can attract protons from a donor. Moreover, the electronegative atoms usually involved in hydrogen bonding are oxygen, nitrogen and fluorine. How many hydrogen bond acceptors does the molecule contain?