XFEL Microcrystallography of Self-Assembling Silver n-Alkanethiolates

Area of Science:

• Materials Science
• Crystallography
• Nanotechnology

Background:

• Synthesizing complex hybrid materials requires advanced characterization techniques.
• Traditional single-crystal X-ray diffraction is limited by the availability of suitable crystals.
• Characterizing microcrystalline materials with small or defective crystals presents significant challenges.

Purpose of the Study:

• To employ small-molecule serial femtosecond crystallography (smSFX) for atomic resolution analysis of silver n-alkanethiolates.
• To resolve controversies regarding atomic connectivity and layer stacking in silver alkanethiolates.
• To investigate the odd-even effects in the crystal structures of silver alkanethiolates with varying alkyl chain lengths.

Main Methods:

• Utilized small-molecule serial femtosecond crystallography (smSFX) at X-ray free electron laser facilities.
• Achieved atomic resolution (0.833 Å) characterization of microcrystalline silver n-alkanethiolates.
• Employed selected-area electron diffraction (SAED) to identify secondary odd-even effects.

Main Results:

• Determined crystal structures of silver n-butanethiolate (C4), silver n-hexanethiolate (C6), and silver n-nonanethiolate (C9).
• Identified the origin of the odd-even effect in layer stacking related to terminal methyl group orientation and packing efficiency.
• Observed a secondary odd-even effect in even-numbered chain crystals due to mosaic block arrangements.

Conclusions:

• smSFX is a powerful technique for characterizing microcrystalline materials, even those with small or defective crystals.
• The study clarifies the atomic structure and packing behavior of silver alkanethiolates, explaining odd-even effects.
• Findings contribute to understanding structure-property relationships in nanomaterials and self-assembled monolayers.