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In the crystal structure of the title compound, 2C6H9N3 C8H6O4, terephthalic acid has a crystallographic inversion centre and the dimethylpyrimidine molecule shows approximate non-crystallographic mirror and twofold rotation symmetry. The inversion-related pyrimidine molecules form a base pair [R2 2(8) ring motif] via a pair of NH⋯N hydrogen bonds. The carboxyl groups of terephthalic acid link the base pairs via OH⋯N and NH⋯O hydrogen bonds [R2 2(8) motif] to generate a supramolecular ribbon. [ABSTRACT FROM AUTHOR]

In the title compound, C12H14ClN4+·C6H4NO2−·H2O, the pyrimethamine molecule is protonated at one of the pyrimidine N atoms. The protonated N atom and 2-amino group of the cation interact with an adjacent nicotinate anion through a pair of N—H...O hydrogen bonds [graph set R22(8)]. The cation, anion and water molecule form a hydrogen-bonded ring motif with graph-set notation R42(8). The crystal structure is further stabilized by N—H...O and O—H...O hydrogen bonds and π–π interactions [centroid–centroid distance = 3.637 (6) Å]. [ABSTRACT FROM AUTHOR]

In the title compounds, namely 2,4-diamino-5-[(3,4,5-trimethoxy­phenyl)methyl]­pyrimidin-1-ium pyridine-2-carboxyl­ate, C14H19N4O3+·C6H4NO2−, (I), and 2-amino-4,6-dimethyl­pyrimidin-1-ium pyridine-2-carboxyl­ate hemihydrate, C6H10N3+·C6H4NO2−·0.5H2O, (II), the trimethoprim and 2-amino-4,6-dimethyl­pyrimidin-1-ium cations are protonated at one of the pyrimidine N atoms. In (I), bifurcated hydrogen bonds are observed between a picolinate O atom, the protonated N atom and the 2-amino group; the graph-set designator is R21(6). The pyrimidine moieties of the trimethoprim cations are centrosymmetrically paired through a pair of N—H⋯N hydrogen bonds. In addition to the base pairing, one of the picolinate O atoms bridges the 2- and 4-amino groups on either side of the paired bases, resulting in a complementary DADA array. In (II), the carboxyl­ate group of the picolinate anion binds with the protonated pyrimidine N atom and the 2-amino group of the pyrimidine moiety through a pair of N—H⋯O hydrogen bonds, leading to the common ring motif R22(8). The water mol­ecule, which resides on a twofold rotation axis, bridges the carboxyl­ate group of the picolinate anion via O—H⋯O hydrogen bonds. [ABSTRACT FROM AUTHOR]

In the title compound [systematic name: 2,4-diamino-5-(3,4,5-trimethoxy­benz­yl)pyrimidinium tetrafluoroborate], C14H19N4O3+·BF4−, the trimethoprim (TMP) mol­ecule is protonated at one of the pyrimidine N atoms. The protonated N atom and 2-amine group of the TMP cation inter­act with the tetrafluoroborate anion through a pair of N—H⋯F hydrogen bonds [graph set R22(8)]. The inversion-related TMP cations are linked through a pair of N—H⋯N hydrogen bonds. The 2-amine group of one TMP cation and the 4-amine group of another cation are bridged by a meth­oxy O atom, via N—H⋯O hydrogen bonds. [ABSTRACT FROM AUTHOR]

In the title cocrystal, C6H9N3O2·C7H7NO2, the 2-amino-4,6-dimethoxy­pyrimidine mol­ecule inter­acts with the carboxyl group of the 4-amino­benzoic acid mol­ecule through N—H⋯O and O—H⋯N hydrogen bonds, forming a cyclic hydrogen-bonded motif [ R22(8)]. This motif further self-organizes through N—H⋯O hydrogen bonds to generate an array of six hydrogen bonds with the rings having the graph-set notation R23(6), R22(8), R42(8), R22(8) and R23(6). The 4-amino­benzoic acid mol­ecules self-assemble via N—H⋯O hydrogen bonds to form a supra­molecular chain along the c axis. [ABSTRACT FROM AUTHOR]