Computational Exploration for Revealing Tunable ESIPT/ESDPT Behavior for TrySPy Fluorophore in Solvents with Various Polarities

The asymmetric dual-hydrogen-bond system TrySPy exhibiting ESIPT characteristics has attracted intramolecular double proton transfer (ESIDPT) mechanism under varying solvent polarities (cyclohexane, toluene, THF, acetonitrile) using density functional theory (DFT) and time-dependent DFT (TDDFT) methods. Through comparison of hydrogen bond-related parameters, we confirmed that dual hydrogen bonds of TrySPy are strengthened in the S1 state. Furthermore, we discovered opposite responses of the two hydrogen bonds to solvent polarity in the excited state: O1–H2···N3 strengthens while N4–H5···N6 weakens with increasing polarity. Frontier orbital analysis demonstrates dominant HOMO–LUMO transition (>97%) driving…

• NS
  Natural Science Foundation of Liaoning Province

  Award: 2025-BS-0785
• DO
  Department of Education of Liaoning Province

  Award: LJ212410166034
• SN
  Shenyang Normal University

  Awards: 2025JG38, ZD202304, 2025JG33, 099-52501002
• LR
  Liaoning Revitalization Talents Program

  Award: XLYC2203155