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Updated: May 14, 2026

Preparation of a Corannulene-functionalized Hexahelicene by Copper(I)-catalyzed Alkyne-azide Cycloaddition of Nonplanar Polyaromatic Units
Published on: September 18, 2016
Two polymorphs of 1,8-dichloroanthracene.
Peter Müller1, Frank R Fronczek, Stacey J Smith
1Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Avenue 2-325, Cambridge, MA 02139-4307, USA. pmueller@mit.edu
A new monoclinic crystal form of C(14)H(8)Cl(2) was discovered. Comparing its crystal packing with the orthorhombic form reveals distinct intermolecular C-H···Cl interactions influencing molecular arrangement.
Area of Science:
- Crystallography
- Solid-state chemistry
- Organic chemistry
Background:
- Polymorphism in organic compounds influences material properties.
- Previous studies described an orthorhombic form of C(14)H(8)Cl(2).
- Limited structural details were available for the orthorhombic form.
Purpose of the Study:
- To identify and characterize a new monoclinic polymorph of C(14)H(8)Cl(2).
- To redetermine the crystal structure of the orthorhombic form using modern techniques.
- To compare the crystal packing and intermolecular interactions of both polymorphs.
Main Methods:
- Single-crystal X-ray diffraction.
- Low-temperature structural analysis.
- Comparative crystallographic analysis.
Main Results:
- A second, monoclinic, polymorph of C(14)H(8)Cl(2) was successfully synthesized and characterized.
- The crystal structure of the orthorhombic form was redetermined at low temperature with improved resolution.
- The monoclinic form exhibits one C-H···Cl interaction forming ribbons, while the orthorhombic form displays two independent C-H···Cl interactions forming a 3D network.
Conclusions:
- The discovery of a new polymorph highlights the complex solid-state behavior of C(14)H(8)Cl(2).
- Detailed structural comparison reveals differences in intermolecular interactions and crystal packing between the two forms.
- Understanding these packing differences is crucial for predicting and controlling material properties.
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