Molecular Association of Almotriptan with Oxalate and Terephthalate Anions

Abstract

Crystal structures of anti-migraine drug almotriptan were crystallized with oxalic acid (I) and with terephthalic acid (II) and their crystal structures and molecular associations were determined using X-ray diffraction methods. Crystals of both (I) and (II) are monoclinic, space group P21/c, with a = 5.6270(4) A, b = 27.6419(19) A, c = 13.6228(9) A, β = 93.057(1)°, V = 2115.9(3) A3, Z = 4 (I) and a = 13.3756(15) A, b = 15.6065(17) A, c = 10.7238(12) A, β = 98.017(2)°, V = 2216.7(4) A3, Z = 4 (II). In almotriptan oxalate {systematic name: N,N-dimethyl-2-[5-(pyrrolidin-1-ylsulfonyl-methyl)-1H-indol-3-yl]-ethanaminium semioxalate}, C17H26N3O2S+, C2HO4 −, (I) and in almotriptan hemi terephthalate hydrate {systematic name: N,N-dimethyl-2-[5-(pyrrolidin-1-ylsulfonyl-methyl)-1H-indol-3-yl]-ethanaminium hemi terephthalate monohydrate}, C17H26N3O2S+, 0.5(C8H4O4 2−), H2O, (II), both the almotriptan cations form a trimer with the corresponding anions via N–H···O hydrogen bonds. In (I), the oxalate salt is monoprotonated and in (II), the terephthalic acid is located across the inversion centre and exists as doubly protonated anion. In (I), the cation and anion are interlinked by the N–H···O and O–H···O hydrogen bonds into continuous two-dimensional layers generate an R 6 6 (34) hydrogen-bonded motif tetramers running parallel to the (0 0 1) plane. In (II), the cation and water form a centrosymmetric tetramer of R 4 4 (22) hydrogen-bonded motif via N–H···O and O–H···O hydrogen bonds and further cross-linked by centrosymmetric anions to form an infinite three-dimensional supramolecular hydrogen-bonded networks. In the present study, we have determined the crystal structures of almotriptan with oxalate and terephthalate anions. .