4-Bromo-1H-pyrrole-2-carb-oxy-lic acid.

In the title compound, C(5)H(4)BrNO(2), the non-H atoms of the pyrrole ring and the Br atom are approximately coplanar, with an r.m.s. deviation from the best fit plane of 0.025 (6) Å;. The dihedral angle between the plane of the carb-oxy group and this plane is 14.1 (2)°. In the crystal, O-H⋯O hydrogen bonds link the mol-ecules together, forming corrugated sheets parallel to the bc plane.

9-Allyl-9H-carbazole-3,6-dicarbaldehyde.

In the title mol-ecule, C(17)H(13)NO(2), the allyl group is almost perpendicular to the carbazole mean plane, with a dihedral angle of 89.0 (2)°. In the crystal, nonclassical C-H⋯O hydrogen bonds link the mol-ecules into corrugated sheets parallel to the bc plane. Weak inter-molecular π-π inter-actions are observed between the benzene rings [centroid-centroid distance = 3.874 (4) Å] from neighbouring sheets.

A second monoclinic polymorph of 1-benzyl-N-methyl-1H-pyrrole-2-carboxamide.

In the title compound, C(13)H(14)N(2)O, the N(pyrrole)-C(H(2))-C-C torsion angle is -7.7 (3)° and the dihedral angle between the pyrrole and benzene rings is 83.6 (2)°. In the crystal, inter-molecular N-H⋯O hydrogen bonds link the mol-ecules into chains extending along the c axis. We have previously reported another polymorphic form of this title compound, which has the same space group with different cell parameters: a = 9.8285 (18) Å, b = 23.588 (4) Å, c = 9.9230 (17) Å, ß = 90.107 (3)°, Z = 8 and V = 2300.5 (7) Å(3) [Zeng et al. (2010 ▶). Acta Cryst. E66, o2051].

rac-Dimethyl 2-(1H-pyrrole-2-carboxamido)-butane-dioate.

The title compound, C(11)H(14)N(2)O(5), was synthesized by condensation of (RS)-2-amino-succinic acid dimethyl ester with 2-trichloro-acetyl-pyrrole at room temperature. The amide group is twisted by 7.4 (1)° from the plane of the pyrrole ring. In the crystal, mol-ecules are linked by inter-molecular N-H⋯O hydrogen bonds into chains extending along the c axis.

Methyl 2-(1H-indole-3-carboxamido)-acetate.

The title compound, C(12)H(12)N(2)O(3), was synthesized by condensation of methyl amino-acetate with 3-trichloro-acetyl-indole. In the crystal, inter-molecular N-H⋯O hydrogen bonds link the mol-ecules into chains parallel to the b axis. The chains are further connected into a three-dimensional network by N-H⋯O hydrogen bonds involving the indole N atom. In the molecule, the indole skeleton is nearly planar [maximum deviation = 0.012 (1) Å] and the mean plane of the amido group is twisted from the mean plane of indole ring by 17.2 (1)°.

2-Iodo-5-nitro-thio-phene.

The title compound, C(4)H(2)INO(2)S, was synthesized by nitration of iodo-thio-phene with acetyl nitrate. The molecule is essentially planar, withthe nitro group tilted by 1.78 (19)° and the iodine atom displaced by 0.0233 (2) Šwith respect to the thiophene ring. In the crystal structure, adjacent mol-ecules are linked through weak I⋯O inter-actions [3.039 (2)Å], forming chains extending along the b axis.

Methyl 3-(1H-indole-3-carboxamido)propionate hemihydrate.

The title compound, C(13)H(14)N(2)O(3)·0.5H(2)O, was synthesized by the condensation of methyl 3-amino-propionate with 3-trichloro-acetyl-indole. The two organic mol-ecules in the asymmetric unit are both close to planar, with r.m.s. deviations from the best fit plane through all of the non-H atoms of 0.004 (2) Šfor mol-ecule A and 0.006 (1) Šfor mol-ecule B. Also, the five- and six-membered rings of the indole systems are inclined at 1.67 (8) and 1.50 (8)° in mol-ecules A and B, respectively. In the crystal structure, the organic molecules are connected by inter-molecular N-H⋯O hydrogen bonds, forming chains. O-H⋯O and N-H⋯O hydrogen-bond inter-actions involving the water molecules inter-link these chains, forming double chains approximately parallel to the a axis.

1-Benzyl-N-methyl-1H-pyrrole-2-carboxamide.

The asymmetric unit of the title compound, C(13)H(14)N(2)O, contains two independent mol-ecules, which differ in the twist of the phenyl ring: the N(pyrrole)-C(H(2))-C-C torsion angles are -73.0 (3) and 17.1 (3)°. In the crystal structure, mol-ecules are linked through N-H⋯O hydrogen bonds into chains extending along the a axis.

Methyl 3-[(1-butyl-1H-indol-3-yl)carbonyl-amino]propionate.

In the title mol-ecule, C(17)H(22)N(2)O(3), the mean plane of the terminal (C=O)OMe fragment and the indole plane form a dihedral angle of 78.94 (3)°. Inter-molecular N-H⋯O hydrogen bonds link the mol-ecules into chains extended along the c axis. The crystal packing exhibits π-π inter-actions, indicated by the short distance of 3.472 (2) Šbetween the centroids of the five-membered heterocycles of neighbouring mol-ecules.

3-(1-Ethyl-1H-pyrrole-2-carboxamido)propionic acid monohydrate.

The title compound, C(10)H(14)N(2)O(3)·H(2)O, was synthesized by alkyl-ation of methyl 3-(1H-pyrrole-2-carboxamido)-propion-ate with ethyl bromide, followed by saponification and acidification. In the crystal structure, inter-molecular O-H⋯O and N-H⋯O hydrogen bonds link the mol-ecules, forming layers parallel to the ac plane.

1-Ethyl-1H,6H-pyrrolo[2,3-c]azepine-4,8(5H,7H)-dione.

The title compound, C(10)H(12)N(2)O(2), was synthesized by cyclization of 3-(1-ethyl-pyrrole-2-carboxamido)propanoic acid in the presence of polyphospho-ric acid and diphospho-rus pentoxide. In the crystal structure, adjacent mol-ecules are linked by N-H⋯O hydrogen bonds, forming chains extending along the b axis.

1H-Pyrrole-2-carboxylic acid.

In the title compound, C(5)H(5)NO(2), the pyrrole ring and its carboxyl substituent are close to coplanar, with a dihedral angle of 11.7 (3)° between the planes. In the crystal structure, adjacent mol-ecules are linked by pairs of O-H⋯O hydrogen bonds to form inversion dimers. Additional N-H⋯O hydrogen bonds link these dimers into chains extending along the a axis.

Methyl (1H-pyrrol-2-ylcarbonyl-amino)acetate.

In the crystal structure of the title compound, C(8)H(10)N(2)O(3), mol-ecules are linked by N-H⋯O hydrogen bonds, forming ribbons of centrosymmetric dimers extending along the c axis.