The Jahn-Teller Effect Meets Solvation: Additive Forces Behind Charge Localization in C₃-Symmetric Donor-Acceptor...

Symmetry-breaking charge transfer in photoexcited donor-acceptor octupolar molecules is a critical phenomenon for molecular electronics, yet a unified understanding of its driving forces remains to be fully understood. While symmetry-breaking charge transfer in symmetric octupolar molecules is driven by solvation, the intramolecular charge transfer dynamics is additionally modulated by the Jahn-Teller effect, which is intrinsic to such systems. Usually, these two types of interaction are analyzed independently, overlooking their possible synergy. A unified theoretical model of the combined influence of the Jahn-Teller effect and solute-solvent interactions on symmetry-breaking charge transfer in excited octupolar molecules with C₃ symmetry is developed. The key finding is the additivity of the effects of these two distinct interactions on symmetry-breaking charge transfer. This synergy is quantified by a single effective parameter, enabling an accurate prediction of the emergent dipole moment. One consequence of this additivity is that, when the Jahn-Teller effect is strong, the degree of symmetry breaking may depend weakly on the polarity of the solvent. The scope of the identified regularities extends beyond the bounds of donor-acceptor compounds, encompassing mixed-valence complexes as well. Our results provide a fundamental predictive tool for the rational design of octupolar materials, where the internal structure and the external environment can be cooperatively tuned to achieve desired charge-separated states for applications in nonlinear optics and molecular electronics.