Structural Features in Crystals of Derivatives of Benzene with Multiple Contiguous Phenyl Substituents

Abstract

Hexaphenylbenzene and related derivatives of benzene with multiple contiguous phenyl substituents have well-defined nonplanar topologies. Their structures limit conjugation and disfavor intermolecular π−π and C−H···π interactions. Such compounds therefore show higher HOMO−LUMO gaps, lower degrees of self-association, less efficient packing, and higher solubilities than planar analogues. These characteristic properties underlie the growing utility of nonplanar phenyl-substituted benzenes in science and technology. Surprisingly, no systematic structural analysis of compounds of this type has been reported. We have now examined structural features in crystals of hexaphenylbenzene, 1,2,4,5-tetraphenylbenzene, 1,4-dimethyl-2,3,5,6-tetraphenylbenzene, pentaphenylbenzene, 1-methyl-2,3,4,5,6-pentaphenylbenzene, and an octaphenyl-p-quinquephenyl. These compounds tend to crystallize in sheets held together by van der Waals contacts and small numbers of C−H···π interactions. Although the nonplanar topologies of these compounds do not eliminate C···H contacts entirely, the ratios of H···H contacts to C···H contacts greatly exceed those found in analogous aromatic compounds that can assume planar structures. Our structural analyses promise to help explain the characteristic behavior of nonplanar aryl-substituted arenes and to accelerate the discovery of new applications.

Two different one-dimensional supramolecular chains formed from the reaction of 2-[1-(pyridin-4-ylmethyl)-1H-benzimidazol-2-yl]quinoline with two different precursors, Co(NO3)2 and CoCl2

“…5c). The C-HÁ Á Á distances are in close agreement with previously reported values (Gagnon et al, 2010). The result is that a novel twodimensional sheet is generated in the ab plane (Fig.…”

Turn‐On Fluorescence and Unprecedented Encapsulation of Large Aromatic Molecules within a Manganese(II)–Triazole Metal–Organic Confined Space

“…These are well over 1 Å longer than the shortest phenyl⋅⋅⋅phenyl contacts of 3.4 Å observed for common TCPE derivatives and TTPE itself, in which the nearest intermolecular phenyl⋅⋅⋅phenyl rings are 4.406(27) Å. Moreover, the shortest H⋅⋅⋅H contacts between nearest TTPE neighbors, a parameter often cited in connection with molecular aggregation chromophores,27–29 are 3.483(41) in 1 and 3.428(45) Å in 2 . Once again, these contacts are more than 1 Å longer than in molecular crystals of other TCPE derivatives, including TTPE, in which the corresponding value is only 2.939(45) Å.…”

Influence of the number and substitution position of phenyl groups on the aggregation-enhanced emission of benzene-cored luminogens

“…2B, S16 and S17, ESI †). Moreover, due to the more crowded substituted phenyl rings on the benzene cores as indicated by their single crystals, PPB (CCDC 769270) 13 and HPB (CCDC 609800) 14 possess the dihedral angles of 56.09-72.92 o and 65.14-88.59 o , respectively ( Fig. S18 and S19, ESI †), which are more twisted than that of 1,2,4,5-TPB.…”