Supramolecular Synthesis by Cocrystallization of Oxalic and Fumaric Acid with Diazanaphthalenes

Abstract

1:1 cocrystals of oxalic and fumaric acid with 1,4-diazanaphthalene (quinoxaline) and 2,3-diazanaphthalene (phthalazine) were prepared. 1,5-Diazanaphthalene (naphthyridine) formed a 1:1 cocrystal only with oxalic acid. X-ray structural analyses are reported. The influence of the position of the two nitrogen atoms in these diazanaphthalenes on the crystal packing is analyzed. The gross crystal structure is governed by strong OH···N hydrogen bonds. The fine-tuning of the packing of the cocrystals of quinoxaline with oxalic and fumaric acid occurs via CH···O hydrogen bonds. The stabilization by the CH···O hydrogen bonds leads to a planar sheetlike structure in the cocrystal with fumaric acid, in contrast to the cocrystal with oxalic acid where the optimization of the CH···O hydrogen bonds results in a nonplanar bent structure. The geometrical arrangement of the nitrogen atoms in 1- and 5-positions in naphthyridine allows a planar sheetlike structure in the cocrystal with oxalic acid. In the case of phthalazi...