Computation is increasingly being used to try to accelerate the
discovery of new materials. One specific example of this is porous
molecular materials, specifically porous organic cages, where the
porosity of the materials predominantly comes from the internal cavities
of the molecules themselves. The computational discovery of novel
structures with useful properties is currently hindered by the difficulty
in transitioning from a computational prediction to synthetic realization.
Attempts at experimental validation are often time-consuming, expensive,
and frequently, the key bottleneck of material discovery. In this
work, we developed a computational screening workflow for porous molecules
that includes consideration of the synthetic difficulty of material
precursors, aimed at easing the transition between computational prediction
and experimental realization. We trained a machine learning model
by first collecting data on 12,553 molecules categorized either as
“easy-to-synthesize” or “difficult-to-synthesize”
by expert chemists with years of experience in organic synthesis.
We used an approach to address the class imbalance present in our
data set, producing a binary classifier able to categorize easy-to-synthesize
molecules with few false positives. We then used our model during
computational screening for porous organic molecules to bias toward
precursors whose easier synthesis requirements would make them promising
candidates for experimental realization and material development.
We found that even by limiting precursors to those that are easier-to-synthesize,
we are still able to identify cages with favorable, and even some
rare, properties.