Data-driven discovery of organic electronic materials enabled by hybrid top-down/bottom-up design

Abstract

The high-throughput molecular exploration and screening of organic electronic materials often starts with either a 'top-down' mining of existing repositories, or the 'bottom-up' assembly of fragments based on predetermined rules and known synthetic templates. In both instances, the datasets used are often produced on a case-by-case basis, and require the high-quality computation of electronic properties and extensive user input: curation in the top-down approach, and the construction of a fragment library and introduction of rules for linking them in the bottom-up approach. Both approaches are time-consuming and require significant computational resources. Here, we generate a top-down set of 117K synthesized molecules containing their optimized structures, associated electronic and topological properties and chemical composition, and use these structures as a vast library of molecular building blocks for bottom-up fragment-based materials design. A tool is developed to automate the coupling of these building block units based on their available C(sp2/sp)-H bonds, thus providing a fundamental link between the two philosophies of dataset construction. Statistical models are trained on this dataset and a subset of the resulting hybrid top-down/bottom-up compounds, which enable on-the-fly prediction of key ground state (frontier molecular orbital gaps) and excited state (S1 and T1 energies) properties from molecular geometries with high accuracy across all known p-block organic compound space. With access to ab initio-quality optical properties in hand, it is possible to apply this bottom-up pipeline using existing compounds as molecular building blocks to any materials design campaign. To illustrate this, we construct and screen over a million molecular candidates for efficient intramolecular singlet fission, the leading candidates of which provide insight into the structural features that may promote this multiexciton-generating process.

Reply to Comment on ‘Physics-based representations for machine learning properties of chemical reactions’

“…While open questions undoubtedly exist surrounding interpolation vs. extrapolation as well as designing challenging out-of-sample test sets such as those containing new chemistry [26,28,[42][43][44][45][46][47][48][49], larger [9,50,51] and/or outlier [52] molecules/materials, or new sets appearing over time [53][54][55], this topic remains an ongoing community-wide discussion with no clear best practices, and will not be discussed further here.…”

Aromaticity-driven singlet-triplet inversions

“…Structures and data for all compounds in the FORMED dataset 29 are provided in a Materials Cloud repository at https://doi.org/10.24435/materialscloud:j6-e2. Optimized structures from the final stage of screening and sample input files are available online as Supporting Information.…”

“…Here, we mine a dataset of existing crystal structures to identify compounds which exhibit violations of Hund's rule in the lowest excited states through sequential refinement of the geometry and excitation energies with increasingly precise computational methods (Figure 2). We have recently introduced a curated database tailored to materials design applications, the Fragment-Oriented Materials Design (FORMED) dataset, 29 consisting of over 117,000 experimentally-reported organic crystal structures and their associated optical properties computed with Tamm-Dancoff-approximated time-dependent density functional theory (TDA-TDDFT) with ωB97X-D/6-31G(d) and geometries with GFN2-xTB 30 (Figure 2, top box).…”

Engineering Frustrated Lewis Pair Active Sites in Porous Organic Scaffolds for Catalytic CO2 Hydrogenation

“…After the initial refinement of these linker geometries at a semiempirical level of the theory (GFN2-xTB 32 ), a rigorous in-house Python-based protocol was applied, in a bottom-up fashion, to automatically functionalize each of these linkers in all coupling sites with an acidic borane (-BR 2 ) fragment. 33 The amenable coupling sites are defined as sp 2 carbon atoms with available hydrogens, which were identified using a series of rules based on the connectivity of atoms in each linker geometry. This strategy is motivated by the well-established chemistry of the borylation of arenes, used in the context of FLP chemistry.…”