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Electrophilic 1,2- and 1,4-Addition of X2 to 1,3-Butadiene

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Alkyl Halides

Alkyl Halides

Structural Properties
Alkyl halides are halogen-substituted alkanes wherein one or more hydrogen atoms of an alkane is replaced by a halogen atom such as fluorine, chlorine, bromine, or iodine. The carbon atom in an alkyl halide is bonded to the halogen atom, which is sp3-hybridized and exhibits a tetrahedral shape.
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Published on: July 28, 2018

2,11-Dibromo-5,8-dibut-yl[4]helicene.

Hiroyuki Isobe¹, Taisuke Matsuno, Shunpei Hitosugi

¹Department of Chemistry, Tohoku University, Aoba-ku, Sendai 980-8578, Japan.

Acta Crystallographica. Section E, Structure Reports Online

|May 19, 2012

Summary

This study reveals that a brominated [4]helicene forms homochiral columns in its crystal structure. Molecules with the same helical handedness self-assemble, showcasing unique packing arrangements and short intermolecular contacts.

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Preparation of a Corannulene-functionalized Hexahelicene by Copper(I)-catalyzed Alkyne-azide Cycloaddition of Nonplanar Polyaromatic Units

Preparation of a Corannulene-functionalized Hexahelicene by Copper(I)-catalyzed Alkyne-azide Cycloaddition of Nonplanar Polyaromatic Units

Published on: September 18, 2016

Area of Science:

Organic Chemistry
Crystallography
Supramolecular Chemistry

Background:

Helicenes are polycyclic aromatic hydrocarbons characterized by their helical structure.
Brominated helicenes offer unique electronic and structural properties.
Crystal packing significantly influences the macroscopic properties of molecular compounds.

Purpose of the Study:

To investigate the crystal structure of a brominated [4]helicene.
To analyze the molecular arrangement and intermolecular interactions in the solid state.
To understand the self-assembly behavior of helicene derivatives.

Main Methods:

Single-crystal X-ray diffraction analysis was employed.
The crystal structure of the racemic mixture of C(26)H(26)Br(2) was determined.
Intermolecular distances and contacts were analyzed.

Main Results:

The compound crystallizes as a racemic mixture, but with two unique molecules of the same helical handedness in the asymmetric unit.
Homochiral columns are formed due to the segregation of molecules with the same handedness.
Short intermolecular hydrogen-hydrogen contacts (1.87 and 1.94 Å) were observed in the fjord region.
Stacked molecules exhibit alternate orientations within columns, with the shortest C-C distance being 3.306(4) Å.

Conclusions:

The crystal packing of this brominated [4]helicene is dictated by helical handedness, leading to homochiral columnar assemblies.
The observed intermolecular contacts provide insights into the forces governing helicene self-assembly.
This study contributes to understanding structure-property relationships in complex organic molecules.