Abstract
In the title proton-transfer organic salt, C5H6.3N5 +·C8H4.7O4 −·C3H7NO, the adeninium moiety is protonated at the N atom in the 1-position of the 6-amino-7H-purin-1-ium (adeninium) cation. In the solid state, the second acidic proton of isophthalic acid is partially transferred to the imidazole N atom of the adeninium cation [refined O—H versus N—H ratio = 0.70 (11):0.30 (11)]. Through the partially transferred proton, the adeninium cation is strongly hydrogen bonded (N—H⋯O/O—H⋯N) to the isophthalate anion. This strong interaction is assisted by another N—H⋯O hydrogen bond originating from the adeninium NH2 group towards the isophthalate keto O atom, with an R 2 2(8) graph-set motif. This arrangement is linked via N—H⋯O hydrogen bonds to the O atoms of the carboxylate group of an isophthalate anion. Together, these hydrogen bonds lead to the formation criss-cross zigzag isophthalate⋯adeninium chains lying parallel to (501) and (50-1). The adeninium cations and the isophthalate anions are arranged in infinite π stacks that extend along the c-axis direction [interplanar distance = 3.305 (3) Å]. Molecules are inclined with respect to this direction and within the stacks they are offset by ca. half a molecule each. Combination of the N—H⋯O and O—H⋯N hydrogen bonds with the π–π interactions forms infinitely stacked isophthalate⋯adeninium chains, thus leading to a two-dimensional supramolecular structure with parallel interdigitating layers formed by the π stacked isophthalate⋯adeninium chains. The DMF molecules of crystallization are bonded to the adeninium cations through strong N—H⋯O hydrogen bonds and project into the lattice space in between the anions and cations. There are also C—H⋯O hydrogen bonds present which, combined with the other interactions, form a three-dimensional network. The crystal under investigation was found to be split and was handled as if non-merohedrally twinned.
Highlights
For supramolecular structures comprising 3-carboxybenzoates, see, for example: Siddiqui et al (2012)
In the title proton-transfer organic salt, C5H6.3N5+C8H4.7O4C3H7NO, the adeninium moiety is protonated at the N atom in the 1-position of the 6-amino-7H-purin-1-ium cation
The adeninium cations and the isophthalate anions are arranged in infinite stacks that extend along the caxis direction [interplanar distance = 3.305 (3) Å]
Summary
Vandavasi Koteswara Rao, Tausif Siddiqui, Matthias Zeller and Sherri R. Through the partially transferred proton, the adeninium cation is strongly hydrogen bonded (N—H O/O—H N) to the isophthalate anion. This strong interaction is assisted by another N—H O hydrogen bond originating from the adeninium NH2 group towards the isophthalate keto O atom, with an R22(8) graph-set motif. This arrangement is linked via N—H O hydrogen bonds to the O atoms of the carboxylate group of an isophthalate anion. N—H O and O—H N hydrogen bonds with the – interactions forms infinitely stacked isophthalate adeninium chains, leading to a two-dimensional supramolecular structure with parallel interdigitating layers formed by the stacked isophthalate adeninium chains. The crystal under investigation was found to be split and was handled as if non-merohedrally twinned
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