InChI=1S/C13H12N4O4/c18-11(19)6-5-10(13(20)21)15-17-12-9-4-2-1-3-8(9)7-14-16-12/h1-4,7H,5-6H2,(H,16,17)(H,18,19)(H,20,21)/b15-10-