Cooperative Halogen Bonding and π-π Stacking Interactions as Drivers of Polymorphism

Area of Science:

• Physical Chemistry
• Materials Science
• Crystallography

Background:

• Polymorphism, the existence of multiple crystalline forms, is crucial for material properties.
• Understanding polymorph formation is vital for functional materials, especially in pharmaceuticals.

Purpose of the Study:

• To elucidate the formation mechanisms of two polymorphic forms of a polyyne compound.
• To investigate the role of intermolecular interactions in controlling crystal structure.

Main Methods:

• Single-crystal X-ray diffraction was used for structural analysis.
• Experimental techniques combined with theoretical studies provided a comprehensive understanding.
• Computational modeling was employed to rationalize polymorph formation.

Main Results:

• Two distinct polymorphic forms of the polyyne compound were identified and characterized.
• Halogen bonding and pi-pi stacking interactions were found to be the primary drivers of polymorphism.
• A detailed model explaining the formation of both polymorphs was successfully constructed.

Conclusions:

• The interplay between halogen bonding and pi-pi stacking dictates the formation of polyyne polymorphs.
• This research provides fundamental insights into controlling crystal engineering for functional materials.
• The findings have implications for the rational design of pharmaceutical compounds.