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Hexameric Capsules Studied by Magic Angle Spinning Solid‐State NMR Spectroscopy: Identifying Solvent Molecules in Pyrogallol[4]arene Capsules
Author(s) -
Avram Liat,
Goldbourt Amir,
Cohen Yoram
Publication year - 2016
Publication title -
angewandte chemie international edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 1433-7851
DOI - 10.1002/anie.201506683
Subject(s) - pyrogallol , magic angle spinning , molecule , nuclear magnetic resonance spectroscopy , solid state nuclear magnetic resonance , solvent , spinning , spectroscopy , materials science , magic angle , chemistry , crystallography , polymer chemistry , stereochemistry , organic chemistry , nuclear magnetic resonance , physics , quantum mechanics
Powders of pyrogallol[4]arene hexamers were produced by evaporation from organic solvents and were studied, for the first time, by magic angle spinning solid‐state NMR (MAS ssNMR). Evaporation selectively removed non‐encapsulated solvent molecules leaving stable hexameric capsules encapsulating solvent molecules. After exposure of the powder to solvent vapors, 1 H/ 13 C heteronuclear correlation MAS ssNMR experiments were used to assign the signals of the external and encapsulated solvent molecules. The formed capsules were stable for months and the process of solvent encapsulation was reversible. According to the ssNMR experiments, the encapsulated solvent molecules occupy different sites and those sites differ in their mobility. The presented approach paves the way for studying guest exchange, guest affinity, and gas storage in hexamers of this type in the solid state.