Although defects are prevalent in metal–organic
frameworks
(MOFs) and usually play a crucial role in modulating their performance
in various applications, detailed structural characterizations of
various defects remain a challenging task mainly due to their disordered,
heterogeneous, and local nature. In this work, by using solid-state
nuclear magnetic resonance spectroscopy (SSNMR) techniques in conjunction
with density functional theory (DFT) calculations, it is clearly elucidated
that the trimethylphosphine (TMP)-assisted 31P NMR strategy
is capable of greatly facilitating the qualitative and quantitative
description of the detailed structural and acidic characteristics
as well as the evolution process of various Zr defects with subtle
distinctions in UiO-66 upon moderate thermal treatment, hence surpassing
most conventional analytical techniques. These results offer a fundamental
understanding of the defect chemistry in MOFs