Synthesis and guest inclusion for molecular catcher-based structure determination

Area of Science:

• Crystallography
• Materials Science
• Supramolecular Chemistry

Background:

• Determining molecular structures of long alkyl chain compounds via X-ray diffraction is challenging due to difficulties in growing single crystals.
• Conventional single-crystal X-ray diffraction is often impossible for such compounds.

Purpose of the Study:

• To present detailed protocols for synthesizing a pillar[5]arene-incorporated metal-organic framework (MOF) acting as a 'molecular catcher'.
• To demonstrate the utility of this MOF for rapid and accurate crystal structure determination of long-alkyl-chain compounds without single crystal growth.

Main Methods:

• Synthesis of pillar[5]arene-containing MOF crystals using a pillar[5]arene derivative, tetraphenyl ethylene derivative, and zinc nitrate hexahydrate in N,N-dimethylformamide.
• Inclusion of target long-alkyl-chain compounds into pre-synthesized MOF crystals via soaking.
• X-ray diffraction analysis of the guest-included MOF crystals to determine the guest's molecular structure.

Main Results:

• Successful synthesis of pillar[5]arene-containing MOF crystals suitable for guest inclusion.
• Demonstration of the 'molecular catcher' technique enabling structure determination of challenging long-alkyl-chain compounds.
• The entire structure determination process can be completed within 10 days.

Conclusions:

• The pillar[5]arene-based MOF 'molecular catcher' provides an effective solution for crystal structure determination of compounds that are difficult to crystallize.
• This method bypasses the need for growing single crystals, significantly accelerating the structure elucidation process.
• Detailed protocols are provided for MOF synthesis and its application in structural analysis.