Efficient screening of 2D molecular polymorphs at the solution-solid interface

Area of Science:

• Materials Science
• Crystallography
• Supramolecular Chemistry

Background:

• Multiple polymorphs commonly form during two-dimensional (2D) crystallization of organic molecules.
• Predicting polymorph occurrence and experimentally verifying them remain challenging.
• Existing methods for 2D polymorph screening are limited.

Purpose of the Study:

• To develop a straightforward experimental approach for screening 2D polymorphs.
• To enable rapid discovery and nanoscale separation of multiple 2D polymorphs.
• To demonstrate the method's versatility with different organic building blocks.

Main Methods:

• Utilizing solution flow generated by contacting tissue paper to a sample.
• Creating a lateral density gradient along the substrate surface in situ.
• Employing this gradient for rapid screening and separation of 2D polymorphs.

Main Results:

• Successfully screened 2D polymorphs for three structurally distinct organic building blocks.
• Demonstrated rapid discovery and nanoscale separation of multiple 2D polymorphs in a single experiment.
• Validated the effectiveness of the solution flow-induced density gradient method.

Conclusions:

• The developed method offers a powerful tool for efficient screening of 2D polymorphs.
• This approach simplifies the experimental verification of diverse crystalline structures.
• Facilitates crystal engineering studies by enabling easier access to different 2D polymorphs.