Zwitterionic 1-{(1E)-[(4-hy-droxy-phen-yl)iminio]meth-yl}naphthalen-2-olate: crystal structure and Hirshfeld surface analysis.

The title zwitterion, C17H13NO2 (systematic name: 1-{(1E)-[(4-hy-droxy-phen-yl)iminium-yl]meth-yl}naphthalen-2-olate), features an intra-molecular charge-assisted N+-H⋯O- hydrogen bond. A twist in the mol-ecule is evident around the N-C(hy-droxy-benzene) bond [C-N-C-C torsion angle = 39.42 (8)°] and is reflected in the dihedral angle of 39.42 (8)° formed between the aromatic regions of the mol-ecule. In the crystal, zigzag supra-molecular chains along the a axis are formed by charge-assisted hy-droxy-O-H⋯O(phenoxide) hydrogen bonding. These are connected into a layer in the ab plane by charge-assisted hy-droxy-benzene-C-H⋯O(phenoxide) inter-actions and π-π contacts [inter-centroid distance between naphthyl-C6 rings = 3.4905 (12) Å]. Layers stack along the c axis with no specific inter-actions between them. The Hirshfeld surface analysis points to the significance C⋯H contacts between layers.

Crystal structure of 2-{(E)-[(2-hy-droxy-phen-yl)iminium-yl]meth-yl}-4-methyl-phenolate.

The title compound, C14H13NO2, exists as a zwitterion in the solid state, with the H atom of the phenol group transferred to the imine N atom. The dihedral angle between the planes of the benzene rings is 10.13 (9)°. Intra-molecular N-H⋯O hydrogen bond generate S(6) and S(5) loops. In the crystal, mol-ecules are connected by O-H⋯O hydrogen bonds, generating C(9) chains propagating in the [010] direction.

Crystal structure of (E)-N-[(2-meth-oxy-naphthalen-1-yl)methyl-idene]-3-nitro-aniline.

In the title compound, C18H14N2O3, the dihedral angle between the naphthalene ring system and the benzene ring is 59.99 (13)°. A short intra-molecular C-H⋯N contact closes an S(6) ring. The nitro group is disordered over two orientations in a statistical ratio. In the crystal, weak C-H⋯O hydrogen bonds and very weak π-π stacking inter-actions [centroid-centroid separation = 3.9168 (17) Å] are observed.

rac-3-(4-Hy-droxy-benz-yl)chroman-4-one.

In the racemic title compound, C16H14O3, the ring of the 4-hy-droxy-benzyl substituent group forms a dihedral angle of 80.12 (12)° with the benzene ring of the chromanone system. Two C atoms of the pyran-one ring and the H atoms on the benzyl α-C atom are disordered over two sites, with site-occupation factors of 0.818 (8) and 0.182 (8). The crystal structure is stabilized by O-H⋯O hydrogen bonds, which form parallel one-dimensional zigzag chains down the c axis and are inter-connected by both methine C-H⋯O hydrogen bonds and weak aromatic C-H⋯π inter-actions, giving a sheet structure lying parallel to [011].

Ethyl 3-amino-5-bromo-1-benzo-furan-2-carboxyl-ate.

The title compound, C11H10BrNO3, is close to planar with the benzo-furan unit and the ester group subtending a dihedral angle of 5.25 (2)°. The mol-ecular structure features an intra-molecular N-H⋯O inter-action. In the crystal, N-H⋯O hydrogen bonds involving carboxyl O-atom acceptors generate a chain extending along [201].

Ethyl 5-bromo-3-eth-oxy-carbonyl-amino-1-benzofuran-2-carboxyl-ate.

In the title compound, C14H14BrNO5, the ester group is disordered [occupancy ratio 0.52 (2):0.48 (2)]. The major component is nearly coplanar with the benzofuran plane, subtending a dihedral angle of 7.84 (2)°, while the amide group is twisted out of the benzofuran plane making a dihedral angle of 39.69 (2)°. An intra-molecular N-H⋯O hydrogen bond occurs. In the crystal, pairs of weak C-H⋯O hydrogen bonds link the mol-ecules into inversion dimers, which are further linked via strong N-H⋯O hydrogen bonds, generating a zigzag chain extending along [100].

3-(3,4-Dimeth-oxy-benz-yl)chroman-4-one.

In the title compound, C(18)H(18)O(4), the six-membered chroman-4-one ring adopts an envelope conformation with the C atom bonded to the bridging CH(2) atom as the flap. The dihedral angle between the mean plane of the fused pyranone ring and the dimeth-oxy-substituted benzene ring is 89.72 (2)°. In the crystal, adjacent molecules are linked via C-H⋯π inter-actions.

(1E,4E)-1,5-Bis(thio-phen-3-yl)penta-1,4-dien-3-one.

The title compound, C(13)H(10)OS(2), exhibits twists between the central C(3)O and ethene residues [O-C-C-C torsion angles = -8.4 (3) and 11.8 (3)°], and between the ethene and adjacent thio-phenyl residues [C-C-C-C torsion angles = -4.2 (3) and 10.5 (3)°]. As a result, the mol-ecule is non-planar, the dihedral angle formed between the terminal thio-phenyl groups being 15.45 (10)°. The presence of C-H⋯O inter-actions involving the bifurcated carbonyl O atom leads to supra-molecular arrays in the ac plane. These are linked into a three-dimensional architecture by C-H⋯π inter-actions involving both thio-phenyl residues.

5,7-syn-Bis(trimethylsilyl)-5-norbornene-2,3-endo-dicarboxylic acid: a rare co-existence of dimeric and catemeric synthons.

The crystal and molecular structure of the title compound, C(15)H(26)O(4)Si(2), reveals a self-assembly facilitated via the rare co-existence of dimeric and catemeric patterns, which is attributed to the influence of the trimethylsilyl groups. The structure is dicussed in the context of a database search and subsequent analysis of structures of cis-1,2-dicarboxylic acids.