The crystalline sponge method updated.

Area of Science:

• Crystallography
• Materials Science
• Chemical Analysis

Background:

• Crystalline sponges are porous metal-organic frameworks capable of encapsulating and orienting guest molecules.
• The crystalline sponge method enables X-ray structure analysis of molecules not amenable to traditional crystallography.
• Optimization is needed to enhance the reliability and information yield of this technique.

Purpose of the Study:

• To systematically examine and optimize all steps of the crystalline sponge method.
• To improve the quality and reliability of structural data obtained for guest molecules.
• To establish benchmark tests for evaluating the method's performance with both achiral and chiral compounds.

Main Methods:

• Optimization of crystal preparation, pore-solvent exchange, guest soaking, and X-ray data collection.
• Development of a high-throughput method for optimizing guest soaking conditions.
• Refinement of disorder in the host framework and solvent molecules within the pores.
• Benchmark testing using guaiazulene (achiral) and santonin (chiral) as guest molecules.

Main Results:

• Significant improvements in guest site occupancy and X-ray data quality, especially in high-angle regions.
• Achieved high-quality structural data comparable to conventional methods for achiral molecules (guaiazulene).
• Demonstrated potential for reliable absolute structure determination of chiral molecules (santonin).

Conclusions:

• The optimized crystalline sponge method provides reliable and meaningful chemical information.
• The method shows great promise for the structural analysis of diverse organic molecules, including chiral compounds.
• This work advances chemical crystallography by refining a powerful tool for molecular structure determination.