The HEALED SBU Library of Chemically Realistic Building Blocks for Construction of Hypothetical Metal–Organic Frameworks

Advancements
in hypothetical metal–organic framework (hMOF)
databases and construction tools have resulted in a rapidly expanding
chemical design space for nanoporous materials. The bulk of these
hypothetical structures are constructed using structural building
units (SBUs) derived from experimental MOF structures, often collected
from the CoRE-MOF database. Recent investigations into the state of
these deposited experimental structures’ chemical accuracy
identified an array of common structural errors, including omitted
protons, missing counterions, and disordered structures. These structural
errors propagate into the SBUs mined from experimental MOFs, culminating
in inaccurate hMOF structures possessing net charges or missing atoms
which were not accounted for previously. This work demonstrates how
manual investigation was applied to diagnose structural errors in
SBUs obtained from several popular hMOF construction tools and databases.
An analysis of the prevailing errors discovered during the examination
process is provided along with representative cases to aid with error
detection in future studies involving SBU extraction and hMOF construction.
A novel repair protocol was established and employed to generate a
library of SBUs that are hand-examined and labeled with enhanced detail (HEALED). This repaired library of SBUs contains 952
inorganic SBUs and 568 organic SBUs ideally suited for the generation
of hypothetical frameworks that are chemically accurate and properly
charge labeled. Additionally, case studies following the effects of
SBU errors on electrostatic potential-fitted charges and GCMC-simulated
gas adsorption predictions are presented to highlight the significance
of using chemically accurate hMOF structures exclusively in all screening
efforts going forward.