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An Expansion of Crystalline Sponge X‐ray Analysis to Elucidate the Molecular Structure of Reactive Compounds via Ion Pair Formation
Author(s) -
Taniguchi Yoshimasa,
Matsumoto Rie,
Kadota Tomoyuki
Publication year - 2020
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.202002504
Subject(s) - chemistry , reagent , ion , nucleophile , amine gas treating , crystal structure , reactive intermediate , combinatorial chemistry , crystallography , computational chemistry , organic chemistry , catalysis
The crystalline sponge (CS) method allows structural elucidation of a target compound (guest) in solution by single crystal X‐ray diffraction through trapping the guest into the CS framework. In principle, the CS method is inapplicable to reactive compounds that break the CS framework, such as acidic, basic, or nucleophilic ones. Here, a solution to this problem is disclosed wherein an ion pair of the guest compound is formed during the guest‐soaking step by adding a suitable reagent. The ion pair can be observed and does not damage the CS framework. Using the developed method, amino, guanidino, and amidino compounds have been successfully analyzed as ion pairs with sulfonic acids. Practical utility has been shown because the absolute configurations of optically resolved amine derivatives were revealed with only a few micrograms. This demonstrates that the ion‐pair‐soaking method is simple and expands the range of compounds applicable to the CS method.