O=C1N(CN2CCOCC2)CN(CN2CCOCC2)C(=O)N1Cc1ccc(-c2ccc(CN3C(=O)N(CN4CCOCC4)CN(CN4CCOCC4)C3=O)cc2)cc1
The electronegative atoms usually involved in hydrogen bonding are oxygen, nitrogen and fluorine. How many hydrogen bond acceptors does the molecule contain?