(2E)-3-(2-Fluoro­phen­yl)-1-(4-fluoro­phen­yl)prop-2-en-1-one

In the title compouund, C₁₅H₁₀F₂O, the mol­ecule exists in an E conformation with respect to the C=C bond [1.3382 (16) Å]. The dihedral angle between the fluoro-substituted benzene rings is 6.80 (6)° and the whole mol­ecule is roughly planar (r.m.s. deviation for the non-H atoms = 0.069 Å). In the crystal, mol­ecules are linked by C—H...F and C—H...O inter­actions into sheets lying parallel to the bc plane.

Ethyl 6-(4-meth­oxy­phen­yl)-2-oxo-4-phenyl­cyclo­hex-3-ene­carboxyl­ate

The asymmetric unit of the title compound, C₂₂H₂₂O₄, consists of two independent mol­ecules (A and B). The cyclo­hexene rings adopt slightly distorted sofa conformations in both mol­ecules. The dihedral angles between the benzene rings are 74.16 (13) and 71.85 (13)° in mol­ecules A and B, respectively. In the crystal, weak C—H...O hydrogen bonds link the mol­ecules into a ribbon-like structure along the b axis. Weak C—H...π inter­actions are also observed.

2-Amino-5-methyl­pyridinium 6-oxo-1,6-dihydro­pyridine-2-carboxyl­ate

The anion of the title salt, C₆H₉N₂⁺·C₆H₄NO₃⁻, undergoes an enol-to-keto tautomerism during the crystallization. In the crystal structure, the cation and anion are held together by a relatively short N—H...O hydrogen bond, and the two anions are further connected to each other by a pair of N—H...O hydrogen bonds with an R₂²(8) ring motif, thus forming a centrosymmetric 2 + 2 aggregate. The aggregates are further linked through weak N—H...O and C—H...O hydrogen bonds, resulting a three-dimensional network.

2-Amino-5-methyl­pyridinium 3-chloro­benzoate

The 3-chloro­benzoate anion of the title salt, C₆H₉N₂⁺·C₇H₄ClO₂⁻, is nearly planar with a dihedral angle of 2.44 (13)° between the benzene ring and the carboxyl­ate group. In the crystal, the protonated N atom and the 2-amino group of the cation are hydrogen bonded to the carboxyl­ate O atoms of the anion via a pair of N—H...O hydrogen bonds with an R₂²(8) ring motif, forming an approximately planar ion pair with a dihedral angle of 7.92 (5)° between the pyridinium and benzene rings. The ion pairs are further connected via N—H...O and C—H...O hydrogen bonds, forming a two-dimensional network parallel to the bc plane.

2-Amino-5-methyl­pyridinium 2-amino­benzoate

In the 2-amino­benzoate anion of the title salt, C₆H₉N₂⁺·C₇H₆NO₂⁻, an intra­molecular N—H...O hydrogen bond is observed. The dihedral angle between the ring and the CO₂ group is 8.41 (13)°. In the crystal, the protonated N atom and the 2-amino group of the cation are hydrogen bonded to the carboxyl­ate O atoms via a pair of N—H...O hydrogen bonds, forming an R₂²(8) ring motif. The ion pairs are further connected via N—H...O hydrogen bonds, resulting in a donor–donor–acceptor–acceptor (DDAA) array of quadruple hydrogen bonds. The crystal structure also features a weak N—H...O hydrogen bond and a C—H...π inter­action, resulting in a three-dimensional network.

2-Amino-5-methyl­pyridinium trifluoro­acetate

In the title salt, C₆H₉N₂⁺·C₂F₃O₂⁻, the F atoms of the anion are disordered over two sets of sites, with refined occupancies in a ratio of 0.505 (17):0.495 (17). In the crystal, cations and anions are linked via N—H...O hydrogen bonds, forming R₂²(8) ring motifs. The ionic units are linked into a two-dimensional network parallel to (100) by N—H...O and weak C—H...O hydrogen bonds. The crystal structure is further stabilized by weak C—H...F hydrogen bonds, resulting in a three-dimensional network.

Bis(2,6-diamino-4-chloro­pyrimidin-1-ium) fumarate

In the title salt, 2C₄H₆ClN₄⁺·C₄H₂O₄²⁻, the complete fumarate dianion is generated by crystallographic inversion symmetry. The cation is essentially planar, with a maximum deviation of 0.018 (1) Å. In the anion, the carboxyl­ate group is twisted slightly away from the attached plane, the dihedral angle between the carboxyl­ate and (E)-but-2-ene planes being 12.78 (13)°. In the crystal, the protonated N atom and the 2-amino group of the cation are hydrogen bonded to the carboxyl­ate O atoms of the anion via a pair of N—H...O hydrogen bonds, forming an R₂²(8) ring motif. In addition, another type of R₂²(8) motif is formed by centrosymmetrically related pyrimidinium cations via N—H...N hydrogen bonds. These two combined motifs form a heterotetra­mer. The crystal structure is further stabilized by stong N—H...O, N—H...Cl and weak C—H...O hydrogen bonds, resulting a three-dimensional network.

4,6-Dimeth­oxy-2-(methyl­sulfan­yl)pyrimidine–4-hy­droxy­benzoic acid (1/1)

The base mol­ecule of the title co-crystal, C₇H₁₀N₂O₂S·C₇H₆O₃, is essentially planar, with a maximum deviation of 0.0806 (14) Å for all non-H atoms. The acid mol­ecule is also nearly planar, with a dihedral angle of 8.12 (14)° between the benzene ring and the carb­oxy group. In the crystal, the acid mol­ecules form an inversion dimer through a pair of O—H...O hydrogen bonds with an R₂²(8) ring motif. The pyrimidine mol­ecules are linked on both sides of the dimer into a heterotetra­mer via O—H...N and C—H...O hydrogen bonds with R₂²(8) ring motifs. The heterotetra­mers are further linked by weak C—H...O hydrogen bonds, forming a tape structure along [1-10].