Isonicotinamide-4-methoxybenzoic acid co-crystal (1), C6H6N2O·C8H8O3, is formed through slow evaporation from methanol solution and it undergoes a first-order isosymmetry (monoclinic I2/a ↔ monoclinic I2/a) structural phase transition at Tc= 142.5 (5) K, which has been confirmed by an abrupt jump of crystallographic interaxial angle β from variable-temperature single-crystal XRD and small heat hysteresis (6.25 K) in differential scanning calorimetry measurement. The three-dimensional X-ray crystal structures of (1) at the low-temperature phase (LTP) (100, 140 and 142 K) and the high-temperature phase (HTP) (143, 150, 200, 250 and 300 K) were solved and refined as a simple non-disordered model with final R[F2> 2σ(F2)] ≃ 0.05. The asymmetric unit of (1) consists of crystallographically independent 4-methoxybenzoic acid (A) and isonicotinamide (B) molecules in both enantiotropic phases. Molecule A adopts a `near-hydroxyl' conformation in which the hydroxyl and methoxy groups are positioned on the same side. Both `near-hydroxyl' and `near-carbonyl' molecular conformations possess minimum conformational energies with an energy difference of
Hexamethylenetetramine-benzoic acid (1/2) (HBA) and hexamethylenetetramine-4-methylbenzoic acid (1/2) (HMBA) co-crystals undergo order-disorder structural phase transition from a low-temperature monoclinic crystal structure to a high-temperature orthorhombic crystal structure at the transition temperatures of 257.5 (5) K (Pn ↔ Fmm2) and 265.5 (5) K (P21/n ↔ Cmcm), respectively, using variable-temperature single-crystal X-ray diffraction analysis. The observed phase transitions were confirmed to be reversible first-order transitions as indicated by the sharp endothermic and exothermic peaks in the differential scanning calorimetry measurement. The three-molecule aggregate of HBA and HMBA consists of a hexamethylenetetramine molecule and two benzoic acid or two 4-methylbenzoic acid molecules, respectively. The acid molecules are ordered at the low-temperature phase and are equally disordered over two positions, which are related by a mirror symmetry, at the high-temperature phase. The two-dimensional supramolecular constructs common to both co-crystals are formed by three-molecule aggregates via weak intermolecular C-H...O and C-H...π interactions into molecular trilayers parallel to the ac plane with small XPac dissimilarity indices and parameters. The PIXEL interaction energies of all corresponding molecular contacts were calculated and the results are comparable between HBA and HMBA co-crystals, resulting in similar lattice energies and transition temperatures despite their two-dimensional isostructural relationship. The observed phase transitions of these two energetically similar co-crystals are triggered by similar mechanisms, i.e. the molecular rotator ordering and structural order-disorder transformation, which induced non-merohedral twinning with similar twin matrices in the low-temperature crystal form of both co-crystals.
As a function of temperature, the hexamethylenetetramine-2-methylbenzoic acid (1/2) cocrystal, C6H12N4·2C8H8O2, undergoes a reversible structural phase transition. The orthorhombic high-temperature phase in the space group Pccn has been studied in the temperature range between 165 and 300 K. At 164 K, a t2phase transition to the monoclinic subgroup P21/c space group occurs; the resulting twinned low-temperature phase was investigated in the temperature range between 164 and 100 K. The domains in the pseudomerohedral twin are related by a twofold rotation corresponding to the matrix (100/0-10/00-1. Systematic absence violations represent a sensitive criterium for the decision about the correct space-group assignment at each temperature. The fractional volume contributions of the minor twin domain in the low-temperature phase increases in the order 0.259 (2) → 0.318 (2) → 0.336 (2) → 0.341 (3) as the temperature increases in the order 150 → 160 → 163 → 164 K. The transformation occurs between the nonpolar point group mmm and the nonpolar point group 2/m, and corresponds to a ferroelastic transition or to a t2structural phase transition. The asymmetric unit of the low-temperature phase consists of two hexamethylenetetramine molecules and four molecules of 2-methylbenzoic acid; it is smaller by a factor of 2 in the high-temperature phase and contains two half molecules of hexamethylenetetramine, which sit across twofold axes, and two molecules of the organic acid. In both phases, the hexamethylenetetramine residue and two benzoic acid molecules form a three-molecule aggregate; the low-temperature phase contains two of these aggregates in general positions, whereas they are situated on a crystallographic twofold axis in the high-temperature phase. In both phases, one of these three-molecule aggregates is disordered. For this disordered unit, the ratio between the major and minor conformer increases upon cooling from 0.567 (7):0.433 (7) at 170 K via 0.674 (6):0.326 (6) and 0.808 (5):0.192 (5) at 160 K to 0.803 (6):0.197 (6) and 0.900 (4):0.100 (4) at 150 K, indicating temperature-dependent dynamic molecular disorder. Even upon further cooling to 100 K, the disorder is retained in principle, albeit with very low site occupancies for the minor conformer.
The title 1:1 adduct, C(5)H(5)BrN(2)·C(7)H(6)O(3), contains two mol-ecules of each species in the asymmetric unit, with similar geometries. In the crystal, mol-ecules are linked to form extended chains along [100] by N-H⋯O, O-H⋯O, O-H⋯N and C-H⋯O hydrogen bonds. Adjacent chains are crosslinked via further N-H⋯O inter-actions into sheets lying parallel to (001). The crystal studied was an inversion twin with a 0.54 (2):0.46 (2) domain ratio.
In the anion of the title mol-ecular salt, C(6)H(9)N(2) (+)·C(7)H(3)N(2)O(7) (-), the two nitro groups are twisted from the attached benzene ring with dihedral angles of 27.36 (10) and 4.86 (11)°. The anion is stabilized by an intra-molecular O-H⋯O hydrogen bond, which generates an S(6) ring motif. In the crystal, the cations and anions are linked by N-H⋯O and C-H⋯O inter-actions and are further consolidated by C-H⋯π inter-actions, to generate a three-dimensional network. A short O⋯N contact of 2.876 (2) Å also occurs.
In the title mol-ecular salt, C(6)H(9)N(2) (+)·C(8)H(5)O(4) (-), the anion is stabilized by an intra-molecular O-H⋯O hydrogen bond, which generates an S(7) ring motif. In the crystal, the cations and anions are linked to form extended chains along [001] by O-H⋯O and N-H⋯O hydrogen bonds. Adjacent chains are crosslinked via C-H⋯O inter-actions into sheets lying parallel to (100).
The asymmetric unit of the title compound, C(5)H(6)BrN(2) (+)·C(8)H(5)O(4) (-), consists of two crystallographically independent 2-amino-5-bromo-pyridinium cations (A and B) and two 2-carb-oxy-benzoate anions (A and B). Each 2-amino-5-bromo-pyridinium cation is approximately planar, with a maximum deviation of 0.047 (1) Å in cation A and 0.027 (1) Å in cation B. The 2-amino-5-bromo-pyridinium unit in cation A is inclined at dihedral angles of 4.9 (3) and 2.2 (3)° with the phenyl rings of the A and B 2-carb-oxy-benzoate anions, respectively. The corresponding angles for cation B are 3.0 (3) and 5.6 (3)°. The mol-ecular structure is stabilized by an intra-molecular O-H⋯O hydrogen bond,which generates an S(7) ring motif. The cations and anions are linked via inter-molecular N-H⋯O and C-H⋯O hydrogen bonds, generating R(2) (2)(8) ring motifs. In the crystal packing, mol-ecules are linked into wave-like chains along [001] via adjacent ring motifs. Short inter-molecular distances between the phenyl and pyridine rings [3.613 (4) and 3.641 (4) Å] indicate the existence of π-π inter-actions. The crystal structure is a non-merohedral twin with a contribution of 0.271 (3) of the minor component.
In the title compound, C(6)H(9)N(2) (+)·C(7)H(5)O(3) (-), the protonated 2-amino-5-methyl-pyridinium cation and the 2-hy-droxy-benzoate anion are both essentially planar, with maximum deviations of 0.026 (2) and 0.034 (1) Å, respectively. The anion is stabilized by an intra-molecular O-H⋯O hydrogen bond, which forms an S(6) ring motif. In the solid state, the anions are linked to the cations via pairs of inter-molecular N-H⋯O hydrogen bonds forming R(2) (2)(8) ring motifs. The crystal structure is further stabilized by N-H⋯O and C-H⋯O inter-actions which link the mol-ecules into chains along [010]. A π-π stacking inter-action [centroid-centroid-distance = 3.740 (2) Å] is also observed.
In the title compound, 2C(5)H(6)BrN(2) (+)·C(4)H(2)O(4) (2-)·2H(2)O, the complete fumarate dianion is generated by crystallographic inversion symmetry. The cation is approximately planar, with a maximum deviation of 0.036 (1) Å. In the anion, the carboxyl-ate group is twisted slightly away from the attached plane; the dihedral angle between carboxyl-ate and (E)-but-2-ene planes is 6.11 (14)°. In the crystal, the carboxyl-ate O atoms form bifurcated (N-H⋯O and C-H⋯O) and N-H⋯O hydrogen bonds with the cations. The crystal packing is stabilized by R(2) (2)(8) ring motifs which are generated by pairs of N-H⋯O hydrogen bonds. The crystal structure is further consolidated by water mol-ecules via O(water)-H⋯O and N-H⋯O(water) hydrogen bonds. The components are linked by these inter-actions into three-dimensional network.
In the title compound, C(5)H(6)BrN(2) (+)·C(7)H(5)O(3) (-), the 2-amino-5-bromo-pyridinium cation and 2-hy-droxy-benzoate anion are essentially planar with maximum deviations of 0.020 (1) and 0.018 (2) Å, respectively. The anion is stabilized by an intra-molecular O-H⋯O hydrogen bond, which generates an S(6) ring motif. In the crystal, the cations and anions are linked by N-H⋯O hydrogen bonds into chains propagating along [010]. The chains contain R(2) (2)(8) ring motifs. The structure is further stabilized by π-π stacking inter-actions [centroid-centroid distances = 3.4908 (10) and 3.5927 (10) Å] and also features short Br⋯O contacts [2.9671 (13) Å].
In the title compound, C(5)H(7)N(2) (+)·C(7)H(5)O(3) (-), the carboxyl-ate mean plane of the 4-hydroxy-benzoate anion is twisted by 8.78 (5)° from the attached ring. The cations and anions are linked via O-H⋯O, N-H⋯O and C-H⋯O hydrogen bonds, forming a three-dimensional network. In addition, π-π inter-actions involving the benzene and pyridinium rings, with centroid-centroid distances of 3.5500 (6) and 3.6594 (6) Å, are observed.
In the title 1:1 adduct, C(7)H(5)NO(4)·C(7)H(7)NO(2), the nitro group of the 4-nitro benzoic acid is twisted from the attached ring by 4.40 (8)°. In the crystal, the mol-ecules are linked into ribbon-like structures along [150] and [10] via O-H⋯O, N-H⋯O, N-H⋯N and C-H⋯O inter-molecular hydrogen bonds.
The asymmetric unit of the title compound, C(5)H(7)N(2) (+)·C(7)H(4)NO(4) (-)·C(7)H(5)NO(4), consists of an amino-pyridinium cation, a 4-nitro-benzoate anion and a neutral 4-nitro-benzoic acid mol-ecule. The pyridine ring forms dihedral angles of 64.70 (5)° and 70.37 (5)°, respectively, with the benzene rings of 4-nitro-benzoic acid and 4-nitro-benzoate. In the crystal structure, the cations, anions and the neutral 4-nitro-benzoic acid mol-ecules are linked by O-H⋯O and N-H⋯O hydrogen bonds, forming a two-dimensional network parallel to (001). Adjacent networks are cross-linked via C-H⋯O hydrogen bonds and π-π stacking inter-actions [centroid-centroid distances 3.6339 (6) and 3.6566 (6) Å].
The title compound, C20H28O3, known as 'trichodermaerin' [systematic name: (4E)-4,9,15,16,16-penta-methyl-6-oxa-tetra-cyclo-[10.3.1.0(1,10).0(5,9)]hexa-dec-4-ene-7,13-dione], is a diterpene lactone which was isolated from Trichoderma asperellum. The structure has a tetra-cycic 6-5-7-5 ring system, with the cyclo-hexa-none ring adopting a twisted half-chair conformation and the cyclo-pentane ring adopting a half-chair conformation, whereas the cyclo-heptene and tetra-hydro-furan-anone rings are in chair and envelope (with the methyl-substituted C atom as the flap) conformations, respectively. The three-dimensional architecture is stabilized by C-H⋯O inter-actions.
The asymmetric unit of the title hydrated salt, C22H25N2 (+)·C6H4ClO3S(-)·H2O, comprises two 2-[4-(di-ethyl-amino)-styr-yl]-1-methyl-quinolin-1-ium cations, two 4-chloro-benzene-sul-fon-ate anions and two solvent water mol-ecules. One ethyl group of both cations displays disorder over two positions in a 0.659 (2):0.341 (2) ratio in one mol-ecule and in a 0.501 (2):0.499 (2) ratio in the other. The sulfonate group of one anion is also disordered over two positions in a 0.893 (7):0.107 (7) ratio. The dihedral angle between the mean plane of the quinolinium ring system and that of benzene ring is 10.57 (18)° in one cation and 14.4 (2)° in the other. In the crystal, cations, anions and water mol-ecules are linked into chains along the [010] direction by O-H⋯Osulfonate hydrogen bonds, together with weak C-H⋯Osulfonate and C-H⋯Cl inter-actions. The cations are stacked by π-π inter-actions, with centroid-centroid distances in the range 3.675 (2)-4.162 (3) Å.
Co-crystal is a structurally homogeneous crystalline material that contains two or more neutral building blocks that are present in definite stoichiometric amounts. The main advantage of co-crystals is their ability to generate a variety of solid forms of a drug that have distinct physicochemical properties from the solid co-crystal components. In the present investigation, five co-crystals containing 2-amino-6-chloropyridine (AMPY) moiety were synthesized and characterized.
The title compound crystallizes as a hemihydrate, C18H20N2O5·0.5H2O. The mol-ecule exists in an E conformation with respect to the C=N imine bond. The 4-meth-oxy-phenyl unit is disordered over two sets of sites with a refined occupancy ratio of 0.54 (2):0.46 (2). The dihedral angles between the benzene rings are 29.20 (9) and 26.59 (9)°, respectively, for the major and minor components of the 4-meth-oxy-substituted ring. All meth-oxy substituents lie close to the plane of the attached benzene rings [the Cmeth-yl-O-C-C torsion angles range from -4.0 (12) to 3.9 (2)°]. In the crystal, the components are linked into chains propagating along [001] via N-H⋯O and O-H⋯O hydrogen bonds and weak C-H⋯O inter-actions.
In the structure of the title salt, C20H20NO(+)·C6H4FO3S(-), the 4-(eth-oxy-phen-yl)ethenyl unit is disordered over two positions with a refined site-occupancy ratio of 0.610 (6):0.390 (6). The cation is nearly planar, the dihedral angle between the quinolinium and benzene rings being 6.7 (4) and 1.7 (7)° for the major and minor components, respectively. The eth-oxy group is essentially coplanar with the benzene ring [C-O-C-Cmethy = 177.1 (8) and 177.8 (12)° for the major and minor components, respectively]. In the crystal, cations and anions are linked into chains along the b-axis direction by C-H⋯Osulfon-yl weak inter-actions. These chains are further connected into sheets parallel to (001) by C-H⋯Osulfon-yl weak inter-actions. The chains are also stacked along the a axis through π-π inter-actions involving the quinolinium and benzene rings [centroid-centroid distances = 3.636 (5) Å for the major component and 3.800 (9) Å for the minor component]. C-H⋯π inter-actions are also present.
In the title mixed salt, 2C16H15N2 (+)·C6H4ClO3S(-)·NO3 (-), one of the cations shows whole mol-ecule disorder over two sets of sites in a 0.711 (7):0.289 (7) ratio. The 4-chorobenzenesulfon-ate anion is also disordered over two orientations in a 0.503 (6):0.497 (6) ratio. The cations are close to planar, the dihedral angles between the pyridinium and indole rings being 1.48 (3)° in the ordered cation, and 5.62 (3) and 2.45 (3)°, respectively, for the major and minor components of the disordered cation. In the crystal, the cations are stacked in an anti-parallel manner approximately along the a-axis direction and linked with the anions via N-H⋯O hydrogen bonds and C-H⋯O inter-actions, generating a three-dimensional network. Weak C-H⋯π and π-π inter-actions [with centroid-centroid distances of 3.561 (2)-3.969 (7) Å] are also observed.
In the structure of the title nicotino-nitrile derivative, C19H15N3O, the pyridine ring makes dihedral angles of 11.50 (7) and 43.36 (8)° with the 4-amino-phenyl and phenyl rings, respectively, and the dihedral angle between the phenyl rings is 36.28°. In the crystal, mol-ecules are linked by N-H⋯N hydrogen bonds into wave-like sheets parallel to (10-2). These sheets are stacked by π-π inter-actions between the 4-amino-phenyl rings of adjacent sheets, with centroid-centroid distances of 3.7499 (9) Å. C-H⋯π inter-actions are also present.