Nucleobases are key structure directing agents due to their rich combination of hydrogen bond donor and acceptor positions. Their propensity to self-assemble through hydrogen-bonding interactions has led to a plethora of supramolecular structures. As a significant nucleobase of DNA, adenine is an important naturally occurring nitrogen heterocycle present in nucleic acids.

The inspection of hydrogen bonding network in both compounds; adeninium hydrogen diselenite (I) and adeninium hydrogen selenite (II) shows direct interactions between the cations and the anions. Furthermore, supramolecular homo and hetero-synthons found play an important role in shaping these supramolecular compounds. Moreover, the 1H,9H-adeninium in both structures generate cationic ribbons. In addition to the N—H ···N and C—H ···N hydrogen bonds connecting the bases in (I) and (II), weak stacking interactions are observed between the aromatic rings of the adeninium base in both compounds. The stacking of cations is stabilized in the crystal packing of (I) and (II) by the ionic bridges with the surrounding anions; indeed, anions play an important role in maintaining the three-dimensional network through hydrogen bonds and charge-charge interactions. In (I) the anions exercise their role in solo while in (II) they do it as hexamers. Further, the connectivity between these hexamers in (II) generates a three-dimensional honeycomb-like inorganic framework. This effect should be considered as important in crystal engineering. There is an interesting electrostatic association, seen only in (I), between the SeOH oxygen electron lone pairs and the aromatic cation.