Hydrogen bonding between aromatic H and F groups leading to a stripe structure withR- andS-columns: the crystal structure of (2,7-dimethoxynaphthalen-1-yl)(3-fluorophenyl)methanone and comparison with its 1-aroylnaphthalene analogues

Abstract

In the molecule of (2,7-dimethoxynaphthalen-1-yl)(3-fluorophenyl)methanone, C19H15FO3, (I), the dihedral angle between the plane of the naphthalene ring system and that of the benzene ring is 85.90 (5)°. The molecules exhibit axial chirality, with either an R- or an S-stereogenic axis. In the crystal structure, each enantiomer is stacked into a columnar structure and the columns are arranged alternately to form a stripe structure. A pair of (methoxy)C-H...F hydrogen bonds and π-π interactions between the benzene rings of the aroyl groups link an R- and an S-isomer to form a dimeric pair. These dimeric pairs are piled up in a columnar fashion through (benzene)C-H...O=C and (benzene)C-H...OCH3 hydrogen bonds. The analogous 1-benzoylated compound, namely (2,7-dimethoxynaphthalen-1-yl)(phenyl)methanone [Kato et al. (2010). Acta Cryst. E66, o2659], (II), affords three independent molecules having slightly different dihedral angles between the benzene and naphthalene rings. The three independent molecules form separate columns and the three types of column are connected to each other via two C-H...OCH3 hydrogen bonds and one C-H...O=C hydrogen bond. Two of the three columns are formed by the same enantiomeric isomer, whereas the remaining column consists of the counterpart isomer. In the case of the fluorinated 1-benzoylated naphthalene analogue, namely (2,7-dimethoxynaphthalen-1-yl)(4-fluorophenyl)methanone [Watanabe et al. (2011). Acta Cryst. E67, o1466], (III), the molecular packing is similar to that of (I), i.e. it consists of stripes of R- and S-enantiomeric columns. A pair of C-H...F hydrogen bonds between R- and S-isomers, and C-H...O=C hydrogen bonds between R(or S)-isomers, are also observed. Consequently, the stripe structure is apparently induced by the formation of R...S dimeric pairs stacked in a columnar fashion. The pair of C-H...F hydrogen bonds effectively stabilizes the dimeric pair of R- and S-enantiomers. In addition, the co-existence of C-H...F and C-H...O=C hydrogen bonds makes possible the formation of a structure with just one independent molecule.

Crystal structure of 1-(4-hydroxybenzoyl)-2,7-dimethoxynaphthalene: Contribution of classical and non-classical hydrogen bonding interactions to the molecular packing structure

“…Recently, the authors have found highly efficient diaroylation at peri (1,8)-positions of 2,7-dialkoxynaphthalene compounds [5,6]. peri-Aroylated naphthalene compounds thus obtained are proved to have non-coplanarly accumulated aromatic-rings-structure in crystal, i.e., the aroyl groups are twistedly situated to the naphthalene ring core in a perpendicular fashion [7][8][9]. Besides, the two aroyl groups are ordinarily oriented in an opposite direction with a few exceptional compounds bearing unidirectionally-aligned aroyl groups [10,11].…”

Crystal structure of 7-methoxy-1-{[(E)-2,6-dimethylphenylimino] (phenyl)methyl}-2-naphthol: Clarification of non-covalent bonding interactions on the basis of spatial organization of single molecular structure and the molecular alignments

“…Furthermore, functional group interconversion of 2-and/or 7-alkoxy group to hydroxyl group is also achievable [12]. According to X-ray crystal structure analyses, the aroyl groups in these peri-aroylated naphthalene compounds are attached in a non-coplanar fashion to the naphthalene rings [13][14][15]. In molecular packing of peri-aroylated naphthalene compounds, four kinds of non-covalent bonding interactions, (sp 2 )C-H···O=C hydrogen bond, (sp 3 )C-H···O hydrogen bond, C-H···π hydrogen bonding interaction, and π-π stacking interaction are observed as the determining factors of molecular spatial organization in decreasing order of frequency [16].…”