Dissecting the Roles of Optimal Tuning, Solvation, and Vibrational Corrections in Excited-State Redox Potential Prediction for Organic Photoredox Catalysts
Year: 2026
Type: preprint
Abstract: Department of Chemistry, Emory University Abstract Reliable computational prediction of excited-state redox potentials is central to the rational design of photoredox catalysts and requires accurate treatment of both ground-state redox thermochemistry and excited-state energetics. Although time-dependent density functional theory (TDDFT) provides a practical computational framework, it remains unclear whether these two components should use the same range-separation treatment and how the tuning of 2 range-separated hybrid (RSH) functionals, solvent response, and vibrational corrections affect that choice. We address these questions using a controlled benchmark of 16 structurally related N-aryl phenoxazine photocatalysts with experimental data obtained in dimethylacetamide, comparing default range-separation parameters with gas-phase tuning (GPγT) and two solution-phase tuning schemes based on equilibrium (PVγT) and nonequilibrium (SVγT) polarizable continuum models. The optimal treatment is quantity dependent: default ω values give the lowest errors for ground-state oxidation potentials, whereas solution-phase tuning with PVγT or SVγT reduces the mean absolute errors (MAEs) of transition energies to 0.10–0.13 eV; combining these component-specific treatments with zero-point or full vibrational corrections yields excited-state oxidation-potential MAEs of 0.11–0.13 V, although the required frequency calculations substantially increase the computational cost. These results reveal that applying a single range-separation treatment throughout the calculation is suboptimal and provide a physically motivated, quantity-specific computational strategy for solution-phase excited-state redox predictions that can now be tested across broader photocatalyst classes and solvent environments. 1 Introduction Photocatalysis has emerged as a versatile strategy for promoting chemical transformations through photoinduced electron transfer (PET) under mild conditions.1-8 Although ruthenium and iridium complexes have traditionally been widely used as photoredox catalysts (PCs),5, 9-12 organic PCs are emerging as cheaper and greener alternatives because their photophysical and redox properties can be systematically tuned through molecular design.2, 4, 8, 13-19
Source: ChemRxiv
Authors: Ariel Gale, Bushra Alam, Fang Liu
Institution: Emory University
Language: English
Subfield: Atomic and Molecular Physics, and Optics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W7213957676