Automated Nanocrystalline Sponge Workflow Enabled by 3D Electron Diffraction.

Area of Science:

• Crystallography
• Materials Science
• Organic Chemistry

Background:

• The crystalline sponge (CS) method determines 3D structures of organic molecules without crystallization by using porous materials.
• Current CS limitations include the need for large single crystals and manual analysis for nanocrystals.
• Three-dimensional electron diffraction (3D ED) enables structure determination from nanosized crystals.

Purpose of the Study:

• To develop an automated workflow for ab initio structural analysis of organic molecules in nanocrystalline sponges using 3D ED.
• To demonstrate the general applicability of the nanocrystalline sponge (NanoCS) strategy with automated analysis.

Main Methods:

• A 3D ED-based NanoCS workflow was developed, integrating guest soaking, low-dose cryogenic data collection, and automated structure solution/refinement.
• The AutoSolveX pipeline was enhanced for automated guest identification and structural analysis.
• A nanocrystalline bismuth-based metal-organic framework (MOF), SU-100, was used as the prototype crystalline sponge.

Main Results:

• The NanoCS strategy successfully determined the structures of 10 organic molecules introduced via liquid, solution, or vapor.
• Automated identification and refinement of guest molecules were achieved using AutoSolveX with 3D ED data collected under low electron fluence and cryogenic conditions.
• The periodic arrangement of guest molecules within SU-100 pores was confirmed, mediated by various intermolecular interactions.

Conclusions:

• The NanoCS workflow combined with automated structural analysis provides a practical and high-throughput platform for routine ab initio structure determination.
• This approach overcomes the limitations of traditional CS methods and manual analysis for nanocrystalline materials.
• It enables efficient structural elucidation of organic molecules hosted in nanocrystalline materials.