Crystal structures and Hirshfeld surface analyses of hypoxanthine salts involving 5-sulfosalicylate and perchlorate anions.

Two salts of 1,9-di-hydro-purin-6-one (hypoxanthine), namely, 6-oxo-1,9-di-hydro-purin-7-ium 5-sulfosalicylate dihydrate, C 5 H 5 N 4 O + ·C 7 H 5 O 6 S - ·2H 2 O, ( I ), and 6-oxo-1,9-di-hydro-purin-7-ium perchlorate monohydrate, C 5 H 5 N 4 O + ·ClO 4 - ·H 2 O, ( II ), have been synthesized and characterized using single-crystal X-ray diffraction and Hirshfeld analysis. In both salts, the hypoxanthine mol-ecule is protonated at the N7 position of the purine ring. In salt ( I ), the cation and anion are connected through N-H⋯O inter-actions. The protonated hypoxanthine cations of salt ( I ) form base pairs with another symmetry-related hypoxanthine cation through N-H⋯O hydrogen bonds with an R 2 2 (8) ring motif, while in salt ( II ), the hypoxanthine cations are paired through a water mol-ecule via N-H⋯O and O-H⋯N hydrogen bonds with an R 3 3 (11) ring motif. The packings within the crystal structures are stabilized by π-π stacking inter-actions in salt ( I ) and C-O⋯π inter-actions in salt ( II ). The combination of several inter-actions leads to the formation of supra-molecular sheets extending parallel to (010) in salts ( I ) and ( II ). Hirshfeld surface analysis and fingerprint plots reveal that O⋯H/H⋯O contacts play the major role in the crystal packing of each of the salts, with a 54.1% contribution in salt ( I ) and 62.3% in salt ( II ).