Noncovalent interactions
are essential in the formation and properties
of a diverse range of hybrid materials. However, reliably identifying
the noncovalent interactions in nanocrystalline materials remains
challenging using conventional methods such as X-ray diffraction and
spectroscopy. Here, we demonstrate that accurate atomic positions
including hydrogen atoms can be determined using three-dimensional
electron diffraction (3D ED), from which the entire range of noncovalent
interactions in a nanocrystalline aluminophosphate hybrid material
SCM-34 are directly visualized. The protonation states of both the
inorganic and organic components in SCM-34 are determined from the
hydrogen positions. All noncovalent interactions, including hydrogen-bonding,
electrostatic, π–π stacking, and van der Waals
interactions, are unambiguously identified, which provides detailed
insights into the formation of the material. The 3D ED data also allow
us to distinguish different types of covalent bonds based on their
bond lengths and to identify an elongated terminal P=O π-bond
caused by noncovalent interactions. Our results show that 3D ED can
be a powerful tool for resolving detailed noncovalent interactions
in nanocrystalline materials. This can improve our understanding of
hybrid systems and guide the development of novel functional materials.
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