Using halogen•••halogen interactions or C/N-H•••Cl hydrogen bonding to direct crystal packing in tetrachlorophthalic acid with N-heterocyclic compounds

In exploring tetrachlorophthalic acid (H-2-tcpH) with a series of N-heterocyclic compounds, eight different types of supramolecular complexes have been obtained, namely, [(H-1,10-phen)center dot(H-tcpH)center dot(H-2-tcpH)center dot( CH3OH)] (1), [(H-Hatz)center dot(H-tcpH)] (2), [(H-2-L5)center dot(H-tcpH)(2)] (3), [(H-Hampym)center dot(H-tcpH)] (4), [(H-2-edm)center dot( H-tcpH)(2)] (5), [(H-ahmp)(2)center dot(tcpH)(2)center dot(H2O)] (6), [(H-2-L7)center dot(tcpH)center dot 2(H2O)] (7), and [(H-Bim)center dot(H-tcpH)center dot(H2O)] (8) (in which 1,10-phen = 1,10-phenanthroline, Hatz = 3-amino-1,2,4-triazole, L5 = 1,4-bis[(2-methylimidazole-1-yl)methyl]benzene, Hampym = 2-aminopyrimidine, edm = ethylenediamine, ahmp = 2-amino-4-hydroxy-6-methylpyrimidine, L7 = 1,2-bis[(2-methylimidazole-1-yl)methyl]benzene, Bim = benzimidazole). These eight complexes displayed amusing structural characteristics and a large amount of hydrogen bonding. Of these, crystals 1-5 generated a 3D supramolecular structure through Cl center dot center dot center dot Cl interactions, whilst C-H center dot center dot center dot Cl and N-H center dot center dot center dot Cl hydrogen bonding exists in the 3D construction of complexes 6-8. In addition, all the complexes were fully characterized by single crystal X-ray diffraction analysis, elemental analysis, infrared spectroscopy (IR), and thermogravimetric analysis (TGA).