Study on spatial organization of non-coplanarly accumulated-aromatic rings molecules aiming organic structure materials

Molecules of congested non-coplanarly-accumulated aromatic rings structure such as binaphthyl and biphenyl have attracted the interests of the chemists in organic chemistry and material chemistry fields as unique building blocks affording characteristic optic and electronic properties in addition to construction of chiral molecular scaffold for organic synthesis. To integrate information about stabilization factors of crystalline accumulation state of organic molecules is significantly important as fundamental study for development of such functional organic materials.
Recently, the authors have reported peri(1,8)-selective diaroylation of naphthalene derivatives. According to the X-ray crystal structure analyses of the resulting 1,8-diaroylnaphthalene compounds, they have been proved to have characteristic structure of non-coplanarly aromatic-rings-accumulated structures. As single molecular structure, two aroyl groups are attached to the naphthalene ring in an almost perpendicular fashion and oriented in an opposite direction. The highly congested circumstance leading non-coplanar spatial organization of aromatic rings accumulation of these molecules means the reduced development of conjugation inevitably resulting in relatively lower contribution of interaction originated from conjugated planes. Instead, it affords the opportunity to reveal the normally hidden interactions. The authors have intended to disclose the stabilization factors of non-coplanarly aromatic-rings-accumulated compounds through investigation of the spatial organization of single molecule, the molecular accumulation structure, and the non-bonding molecular interactions in 1,8-diaroylnaphthalene homologues. In the course of these studies, the authors have designed and synthesized 1,8-diaroylated-2,7-dialkoxynaphthalene compounds followed by determination of the crystal structures, e.g., 1,8-bis(4-fluorobenzoyl)-2,7-dimethoxynaphthalene, 2,7-diethoxy-1,8-bis(4-fluorobenzoyl)naphthalene, 2,7-dibutoxy-1,8-bis(4-fluorobenzoyl)naphthalene, and 1,8-bis(4-fluorobenzoyl)-2,7-diphenoxynaphthalene. In this study, the authors will report crystal structure of peri-aroylnaphthalene copounds and discuss the contribution of the non-bonding molecular interactions to stabilization of the molecular packing through comparison of the crystal structures of the homologues in detail.