2-Methyl-3-chloro-9-hydroxy-4-oxo-4H-pyrido[1,2-a]pyrimidine Hydrochloride: Crystal Structure and Interaction with DNA

Abstract

The title compound, C9H8ClN2O2 +·Cl−, is a hydrochloric acid salt of 2-methyl-3-chloro-9- hydroxy-4H-pyrido[1,2-a]pyrimidine-4-one, which is an important intermediate for the synthesis of biologically active heterocyclic compounds. The synthesized compound was characterized by 1H NMR and X-ray crystallography. The structure was solved in monoclinic, space group P21/n with a = 11.8295 (12), b = 6.2214 (6), c = 13.8133 (15) A, β = 97.7860 (10)°, V = 1007.23 (18) A3, Z = 4, and with R int = 0.077. The cation of the title compound, as shown by the single-crystal structure determination, has two conjugated aromatic rings that are almost coplanar with a dihedral angle of 0.230°. The crystal packing is stabilized by intermolecular N–H···Cl, O–H···Cl hydrogen bonds, which link the molecules into centrosymmetric dimers, and by weak π–π stacking interactions (average distance 3.352 A). The interaction of native calf thymus DNA (ctDNA) with the compound at physiological pH was monitored by UV–Vis spectroscopy and viscosimetric techniques. It was found that the compound might interact with ctDNA by a groove mode of binding via hydrogen bonds. The title compound, C9H8ClN2O2 +·Cl−, is a hydrochloric acid salt of 2-methyl-3- chloro-9-hydroxy-4H-pyrido[1,2-a]pyrimidine-4-one, which is an important inter-mediate for the synthesis of biologically active heterocyclic compounds. It was found that the compound might interact with ctDNA by a groove mode of binding.