Covalent-assisted supramolecular synthesis: the effect of hydrogen bonding in cocrystals of 4-tert-butylbenzoic acid with isoniazid and its derivatized forms.

A series of cocrystals of isoniazid and four of its derivatives have been produced with the cocrystal former 4-tert-butylbenzoic acid via a one-pot covalent and supramolecular synthesis, namely 4-tert-butylbenzoic acid-isoniazid, C6H7N3O·C11H14O2, 4-tert-butylbenzoic acid-N'-(propan-2-ylidene)isonicotinohydrazide, C9H11N3O·C11H14O2, 4-tert-butylbenzoic acid-N'-(butan-2-ylidene)isonicotinohydrazide, C10H13N3O·C11H14O2, 4-tert-butylbenzoic acid-N'-(diphenylmethylidene)isonicotinohydrazide, C19H15N3O·C11H14O2, and 4-tert-butylbenzoic acid-N'-(4-hydroxy-4-methylpentan-2-ylidene)isonicotinohydrazide, C12H17N3O2·C11H14O2. The co-former falls under the classification of a `generally regarded as safe' compound. The four derivatizing ketones used are propan-2-one, butan-2-one, benzophenone and 3-hydroxy-3-methylbutan-2-one. Hydrogen bonds involving the carboxylic acid occur consistently with the pyridine ring N atom of the isoniazid and all of its derivatives. The remaining hydrogen-bonding sites on the isoniazid backbone vary based on the steric influences of the derivative group. These are contrasted in each of the molecular systems.

2-[(2Z)-Azepan-2-yl-idene]-1-(4-nitro-phen-yl)ethanone.

The title compound, C(14)H(16)N(2)O(3), is an NH-vinyl-ogous amide (enaminone) produced by the reaction of 4-nitro-phenacyl bromide with azepane-2-thione. The conformation about the C=C bond [1.3927 (14) Å] is Z, which allows for the formation of an intra-molecular N-H⋯O hydrogen bond that leads to an S(6) loop. Inversion-related mol-ecules associate via N-H⋯O hydrogen bonds to form a 12-membered {⋯OC(3)NH}(2) synthon.

(2E)-1-Phenyl-2-[1-(2-phenyl-prop-2-en-1-yl)pyrrolidin-2-yl-idene]ethanone.

The title compound, C21H21NO, is a vinyl-ogous amide (enaminone) produced by reaction of 1-(2-phenyl-prop-2-en-1-yl)pyrrolidine-2-thione with phenacyl bromide. In the mol-ecule, the phenyl rings are twisted from the mean plane of the pyrrolidine ring by 11.2 (1) and 67.3 (1)°. In the crystal, weak C-H⋯O hydrogen bonds link the mol-ecules related by translation along the b axis into chains.

2,3-Dihydro-1H-pyrrolo-[1,2-a]indole-9-carbonitrile.

The asymmetric unit of the title compound, C12H10N2, which may serve as a model for mitosenes, contains two independent mol-ecules. The conformation of the five-membered rings in both molecules is envelope, with the central CH2-CH2-CH2 C atom at the flap in each case. In the crystal, they inter-act by a combination of weak C-H⋯N and π-π inter-actions [centroid-centroid distances = 3.616 (1) and 3.499 (1) Å] and C-H⋯π contacts.

(±)-(rel-3R,3'R)-1,1'-Dimethyl-3,3'-bipyrrolidine-2,2'-dithione.

The asymmetric unit of the racemic title compound, C(10)H(16)N(2)S(2), a C(2)-symmetric bis-(thiol-actam), contains one half-mol-ecule, the complete mol-ecule being generated by a twofold axis symmetry operation. The five-membered ring is nearly planar, with a maximum deviation of 0.025 (1) Å. In the crystal, the mol-ecules are linked via weak C-H⋯S inter-actions, forming infinite chains along the b-axis direction.

Isonicotinamide-2-naphthoic acid (1/1).

In the title 1:1 adduct, C(6)H(6)N(2)O·C(11)H(8)O(2), the amide group is slightly twisted out of the plane of the aromatic ring, with a C-C-C-N torsion angle of 25.11 (19)°, whereas the carb-oxy-lic acid group is approximately coplanar with the bicylic ring system, with a C-C-C-O torsion angle of 10.9 (2)°. The amide groups from two isonicotinamide mol-ecules form a dimer via N-H⋯O hydrogen bonds. In addition, the 2-naphthanoic acid mol-ecule is hydrogen bonded to the pyridine unit of an isonicotinamide mol-ecule via an O-H⋯N hydrogen bond. This gives rise to a centrosymmetric four-mol-ecule chain, which is cross-linked by further N-H⋯O hydrogen bonds from the amide group.