A study of the crystal structures, supra-molecular patterns and Hirshfeld surfaces of bromide salts of hypoxanthine and xanthine.

Two new crystalline salts, namely, hypoxanthinium bromide monohydrate, CHNO·Br·HO () and xanthinium bromide monohydrate, CHNO ·Br·HO (), were synthesized and characterized by single-crystal X-ray diffraction technique and Hirshfeld surface analysis. The hypoxanthinium and xanthinium cations in salts and are both in the oxo-N(9)-H tautomeric form. The crystal packing of the two salts is governed predominantly by N-H⋯O, N-H⋯Br, C-H⋯Br and O-H⋯Br inter-actions described by (9) and (8) synthons. The crystal packing is also consolidated by carbon-yl⋯π inter-actions between symmetry-related hypoxanthinium ( ) cations in salt and xanthinium cations ( ) in salt . The combination of all these inter-actions leads to the formation of wave- and staircase-like architectures in salts and , respectively. The largest contributions to the overall Hirshfeld surface are from Br⋯H/H⋯Br contacts (22.3% in and 25.4% in ) .