The aromatic rings in 2,7-dimethoxy-1,8-bis(1-naphthoyl)naphthalene in crystal accumulate non-coplanarly to each other, with the dihedral
angle between the terminal naphthalene and the 2,7-dimethoxynaphthalene rings of closer to 90˚ than the homologous compounds, 1,8-
dibenzoyl-2,7-dimethoxynaphthalene and 2,7-dimethoxy-1,8-bis(2-naphthoyl)naphthalene. Molecular packing structures of the title
compound and the homologous two compounds are classified by screw-sense and orientation of molecular assembly with a two-fold screw
axis. In the title compound, right(left)-handed 21 helical assemblies are oriented in a downward (an upward) direction forming a plane. The
plane is alternately stacked with the counter handed version. In the homologous compounds, right (left)-handed 21 helical assemblies are
oriented in an upward (a downward) direction to form a plane. In other words, the 21 helical assemblies in the molecular packing of the
title compound correspond to the 180˚ rotated one of the homologous compounds as space geometry. In the right(left)-handed 21 helical
assembly of the title compound, two types of effective C–H…O=C hydrogen bonds are observed, i.e., (sp3
)C–H…O=C hydrogen bond and
(sp2
)C–H…O=C hydrogen bond. On the other hand, either of two types of C–H…O=C hydrogen bonds is found in a right(left)-handed 21
helical assembly of the homologous two compounds. Besides, the title compound has (sp3
)C–H…O=C hydrogen bonds between the righthanded 21 helical assembly and the left-handed one, and the homologous two compounds have effective … stacking interactions and
(sp2
)C–H…O=C hydrogen bonds. Cooperative two types of C–H…O=C hydrogen bonds in right(left)-handed helical assembly induce a
downward (an upward) orientation of the 21 helical assemblies, showing P21/c space group. Sole function of either (sp3
)C–H…O=C
hydrogen bond or (sp2
)C–H…O=C one in right(left)-handed helical assembly leads the opposite oriented right(left)-handed 21 helical
assemblies, showing C2/c space group.
Key words: Non-coplanarly accumulated aromatic rings molecule, Cooperative hydrogen bonds, Orientation of 21 helical assembly
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