Benchmarking of Density Functionals for Z-Azoarene Half-Lives via Automated Transition State Search

Abstract

Molecular photoswitches use light to interconvert from a thermodynamically stable isomer into a meta-stable isomer. Chemists and materials scientists have applied photoswitches in photopharmacology, catalysis, and molecular solar thermal (MOST) materials. Visible-light-absorbing photoswitches are attractive because the relatively low-energy light minimizes undesired photochemical reactions and enables biological applications.Designing ideal photoswitches requires long-lived metastable states; predicting their half-lives with theory is difficult because it requires locating transition structures. We now report the EZ-TS code, which automates the prediction of rate constants for the thermal Z → E isomerization. We leverage EZ-TS to automate the location of the favored transition structure and to comprehensively benchmark the performance of 140 model chemistries against the experimental rate constants of 11 azoarenes. We used 28 density functionals [local spin density approximation, generalized gradient approximation, meta-GGA, hybrid GGA, hybrid meta-GGA], and five basis sets [6-31G(d), 6-31+G(d,p), 6-311+G(d,p), cc-pvdz, and aug-cc-pvdz]. The hybrid GGA functionals performed the best of all tested functional classes. We demonstrate that the mean absolute errors of 14 model chemistries approach chemical accuracy, and mPWPW91/6-31+G (d,p) achieves chemical accuracy and should be used with EZ-TS. File list (2) download file view on ChemRxiv Azoarene thermal benchmarking -Final.pdf (1.39 MiB) download file view on ChemRxiv Azoarene benchmarking supporting information.pdf (466.14 KiB) Benchmarking of density functionals for Z-azoarene half-lives via automated transition state search

Thermal Half-Lives of Azobenzene Derivatives: Virtual Screening Based on Intersystem Crossing Using a Machine Learning Potential

“…Further, the program is quite fast, replicating the results of spin-flip, time-dependent density functional theory (SF-TDDFT) in milliseconds through use of a transferable ML potential. This program adds to the growing collection of computational models for predicting photoswitch properties. ,− Our software and pretrained models are freely available at .…”

Efficient Discovery of Visible Light-Activated Azoarene Photoswitches with Long Half-Lives Using Active Search

“…Determining t 1/2 values requires the computation of Z → E thermal isomerization transition structures, which reveal the activation free energies. Adrion et al recently benchmarked 140 model chemistries to predict azoarene isomerization barriers and published the open-access code, EZ -TS. We thus applied EZ -TS to compute the t 1/2 of the Z -isomers of core derivatives with the longest λ max , identified with the active search.…”

“…The VERDE materials DB is unique because it was the first open-access database to include excited state structures (S 0 , S 1 , and T 1 ), photophysical, and redox properties. Further, Adrion et al . published the EZ -TS code, which predicts thermal Z → E activation barriers efficiently and accurately.…”

“…We now combine these existing tools (the VERDE materials DB, EZ -TS, and active search) to automatically identify top photoswitch candidates featuring visible-light λ max and long t 1/2 . The prediction accuracy of our predictive model improves as we frequently query from quantum chemical calculations.…”

Cross-conjugation controls the stabilities and photophysical properties of heteroazoarene photoswitches

“…First, the transition structures were optimized using the EZ -TS code recently reported by our group. 75 After locating the lowest energy transition states, we ran intrinsic reaction coordinate (IRC) calculations and optimized the reactive conformers corresponding to the reactant ( Z -isomer) and product ( E -isomer) for each thermal Z → E isomerization. All calculations were performed using the Gaussian 16 software.…”