Acta Crystallographica Section C

Volume 65, Part 12 (December 2009)

organic compounds

 

Hydrogen bonding and - interactions in 1-benzofuran-2,3-dicarboxylic acid and its 1:1 cocrystals with pyridine, phenazine and 1,4-phenylenediamine

H. M. Titi and I. Goldberg

Abstract: The structure of 1-benzofuran-2,3-dicarboxylic acid (BFDC), C₁₀H₆O₅, (I), exhibits an intramolecular hydrogen bond between one -COOH group and the other, while the second carboxyl function is involved in intermolecular hydrogen bonding to neighbouring species. The latter results in the formation of flat one-dimensional hydrogen-bonded chains in the crystal structure, which are - stacked along the normal to the plane of the molecular framework, forming a layered structure. 1:1 Cocrystallization of BFDC with pyridine, phenazine and 1,4-phenylenediamine is associated with H-atom transfer from BFDC to the base and charge-assisted hydrogen bonding between the BFDC^- monoanion and the corresponding ammonium species, while preserving, in all cases, the intramolecular hydrogen bond between the carboxyl and carboxylate functions. The pyridinium 2-carboxylato-1-benzofuran-3-carboxylic acid, C₅H₆N⁺·C₁₀H₅O₅^-, (II), and phenazinium 3-carboxylato-1-benzofuran-2-carboxylic acid, C₁₂H₉N₂⁺·C₁₀H₅O₅^-, (III), adducts form discrete hydrogen-bonded ion-pair entities. In the corresponding crystal structures, the two components are arranged in either segregated or mixed - stacks, respectively. On the other hand, the structure of 4-aminoanilinium 2-carboxylato-1-benzofuran-3-carboxylic acid, C₆H₉N₂⁺·C₁₀H₅O₅^-, (IV), exhibits an intermolecular hydrogen-bonding network with three-dimensional connectivity. Moreover, this fourth structure exhibits induction of supramolecular chirality by the extended hydrogen bonding, leading to a helical arrangement of the interacting moieties around 2₁ screw axes. The significance of this study is that it presents the first crystallographic characterization of pure BFDC, and manifestation of its cocrystallization with a variety of weakly basic amine molecules. It confirms the tendency of BFDC to preserve its intramolecular hydrogen bond and to prefer a monoanionic form in supramolecular association with other components. The aromaticity of the flat benzofuran residue plays an important role in directing either homo- or heteromolecular - stacking in the first three structures, while the occurrence of a chiral architecture directed by multiple hydrogen bonding is the dominant feature in the fourth.

Formula: C₁₀H₆O₅, C₅H₆N⁺·C₁₀H₅O₅^-, C₁₂H₉N₂⁺·C₁₀H₅O₅^- and C₆H₉N₂⁺·C₁₀H₅O₅^-

	Structure factor file (CIF format) (97.6 kbytes) [ doi:10.1107/S0108270109047519/gd3317Isup2.hkl ] Contains datablock I
	Structure factor file (CIF format) (142.2 kbytes) [ doi:10.1107/S0108270109047519/gd3317IIsup3.hkl ] Contains datablock II
	Structure factor file (CIF format) (96.9 kbytes) [ doi:10.1107/S0108270109047519/gd3317IIIsup4.hkl ] Contains datablock III
	Structure factor file (CIF format) (85.2 kbytes) [ doi:10.1107/S0108270109047519/gd3317IVsup5.hkl ] Contains datablock IV

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