Temperature-Dependent Phase Transition Studies Of Multicomponent Crystals Of Hexamethylenetetramine And Isonicotinamide

In this research, thirty-one multi-component crystals of hexamethylenetetramine and isonicotinamide were successfully prepared and seven of them undergo temperature-dependent phase transitions, which were investigated by using variable-temperature single-crystal X-ray diffraction analysis. These seven multi-component crystals are hexamethylenetetramine‒2-methylbenzoic acid (1/2) (monoclinic P21/c ↔ orthorhombic Pccn, Tc = 164.5 (5) K), hexamethylenetetramine‒benzoic acid (1/2) (monoclinic Pn ↔ orthorhombic Fmm2, Tc = 257.5 (5) K), hexamethylenetetramine‒4-methylbenzoic acid (1/2) (monoclinic P21/n ↔ orthorhombic Cmcm, Tc = 265.5 (5) K), hexamethylenetetramine‒succinic acid (1/1) (monoclinic P21/n ↔ monoclinic P21/c, Tc = 219 (1) K)

5-Bromo-4-(3,4-dimeth­oxy­phen­yl)thia­zol-2-amine

In the title compound, C11H11BrN2O2S, the thia­zole ring makes a dihedral angle of 53.16 (11)° with the adjacent benzene ring. The two meth­oxy groups are slightly twisted from the attached benzene ring with C—O—C—C torsion angles of −9.2 (3) and −5.5 (3)°. In the crystal, mol­ecules are linked by a pair of N—H⋯N hydrogen bonds into an inversion dimer with an R 2 2(8) ring motif. The dimers are further connected by N—H⋯O hydrogen bonds into a tape along [-110]

3,3′-[1,2-Phenyl­enebis(methyl­ene)]bis­(1-propyl­benzimidazolium) dibromide hemihydrate

The asymmetric unit of the title compound, C28H32N4 2+·2Br−·0.5H2O, contains one 3,3′-[1,2-phenyl­enebis(methyl­ene)]bis­(1-propyl­benzimidazolium) cation, two bromide anions and one half-mol­ecule of water. In the crystal, the whole 3,3′-[1,2-phen­yl­enebis(methyl­ene)]bis­(1-propyl­benzimidazolium) cation and one of the bromide anions are each disordered over two positions with site-occupancy ratios of 0.751 (6):0.249 (6) and 0.680 (8):0.320 (8). For the major component of the disordered cation, the central benzene ring forms dihedral angles of 83.6 (5) and 88.2 (4)° with its adjacent imidazole rings, while these angles for the minor component are 89.2 (15) and 84.9 (13)°. In the crystal, the cations and anions are linked by C—H⋯Br hydrogen bonds into dimers and then stacked along the c axis. The crystal packing is further stabilized by C—H⋯π and π–π inter­actions [shortest centroid–centroid distance = 3.646 (4) Å]

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

In the title compound, C15H10ClFO, the fluoro-substituted benzene ring forms a dihedral angle of 44.41 (6)° with the chloro-substituted benzene ring. The only significant directional bonds in the crystal are weak C—H⋯π inter­actions

2-[3,5-Bis­(4-fluoro­phen­yl)-4,5-dihydro-1H-pyrazol-1-yl]-4,6-bis(4-fluoro­phenyl)pyrimidine

In the title compound, C31H20F4N4, the pyrazole ring adopts an envelope conformation and forms a dihedral angle of 9.91 (6)° with the adjacent pyrimidine ring. The pyrimidine ring forms dihedral angles of 9.23 (6) and 2.16 (5)° with its adjacent fluoro-substituted benzene rings, whereas these angles are 88.22 (6) and 9.66 (6)° for the pyrazole ring and its adjacent benzene rings. In the crystal, mol­ecules are linked by C—H⋯F hydrogen bonds into ribbons along [01-1]. The crystal packing is further stabilized by C—H⋯π and by π–π inter­actions, with centroid–centroid distances of 3.7428 (7) and 3.7630 (6) Å

(2E)-2-(4-Fluoro­benzyl­idene)hydrazinecarboxamide

In the title compound, C8H8FN3O, the semicarbazide group is close to being planar, with a maximum deviation of 0.020 (1) Å, and subtends a dihedral angle of 16.63 (9)° with its attached fluoro­benzene ring. In the crystal, mol­ecules are linked by N—H⋯O hydrogen bonds, forming layers lying parallel to the bc plane

1-(5-Bromo-4-phenyl-1,3-thia­zol-2-yl)pyrrolidin-2-one

The asymmetric unit of the title compound, C13H11BrN2OS, consists of two crystallographically independent mol­ecules (A and B). In each mol­ecule, the pyrrolidine ring adopts an envelope conformation with a methyl­ene C atom as the flap atom. In mol­ecule A, the central thia­zole ring makes a dihedral angle of 36.69 (11)° with the adjacent phenyl ring, whereas the corresponding angle is 36.85 (12)° in mol­ecule B. The pyrrolidine ring is slightly twisted from the thia­zole ring, with C—N—C—N torsion angles of 4.8 (3) and 3.0 (4)° in mol­ecules A and B, respectively. In the crystal, C—H⋯π and π–π [centroid-to-centroid distance = 3.7539 (14) Å] inter­actions are observed. The crystal studied was a pseudo-merohedral twin with twin law (-100 0-10 101) and a refined component ratio of 0.7188 (5):0.2812 (5)

(E)-3-Dimethyl­amino-1-(2,5-dimethyl­thio­phen-3-yl)prop-2-en-1-one

In the title compound, C11H15NOS, the 3-(dimethyl­amino)­prop-2-en-1-one unit is approximately planar [maximum deviation = 0.0975 (14) Å] and its mean plane of seven non-H atoms makes a dihedral angle of 6.96 (10)° with the thio­phene ring. In the crystal, mol­ecules are linked by pairs of C—H⋯O hydrogen bonds into inversion dimers with R 2 2(14) ring motifs. The dimers are stacked along the c axis through C—H⋯π inter­actions. The two methyl groups, attached to the thio­phene ring and the amino N atom, are each disordered over two orientations, with site-occupancy ratios of 0.59 (4):0.41 (4) and 0.74 (4):0.26 (4), respectively

(E)-2-Cyano-N′-(1,2,3,4-tetra­hydro­naphthalen-1-yl­idene)acetohydrazide

In the title compound, C13H13N3O, the tetra­hydro­benzene ring adopts a half-boat (envelope) conformation. The mean plane of the tetra­hydro­naphthalene ring system forms a dihedral angle of 9.56 (6)° with the mean plane of the cyano­acetohydrazide group. In the crystal, inversion dimers linked by pairs of N—H⋯O hydrogen bonds generate R 2 2(8) loops. The dimers are connected by C—H⋯N hydrogen bonds into a chain propagating along [101]. The crystal packing also features C—H⋯π inter­actions