Solvent Dynamics and Multiconfigurational Treatment Drive the Anomalous Stokes Shift of HINA
- 1Aix Marseille University
- 2Institut Universitaire de France
Abstract
The 3-hydroxyisonicotinaldehyde (HINA) anion is one of the smallest known green-emissive fluorophores, yet the origin of its anomalously large Stokes shift (0.87 eV) remains unexplained. Given the well-established influence of the surrounding environment on the photophysical properties of fluorescent dyes, we examine its role in this shift by simulating the anion's absorption and emission spectra with four computational protocols that differ in configurational sampling, solvent treatment, and electronic-structure method. Wigner sampling protocols capture less than half of the experimental Stokes shift, whether the solvent is treated implicitly or explicitly, whereas QM/MM molecular dynamics sampling improves it significantly. Structural analysis associates this improvement with coupling between the first solvation shell and the intramolecular interaction between the aldehyde hydrogen and the hydroxyl oxygen, which is captured by molecular-dynamics sampling but not by the corresponding frozen-solute Wigner-sampling protocol. When combined with RMS-CASPT2, this sampling quantitatively reproduces the experimental spectra and Stokes shift (0.85 versus 0.87 eV), showing that quantitative description of the Stokes shift of HINA requires both solvent-induced conformational dynamics and a multiconfigurational electronic-structure treatment.
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BibTeX
@misc{albani2026solvent,
title = {{Solvent Dynamics and Multiconfigurational Treatment Drive the Anomalous Stokes Shift of HINA}},
author = {Carlo Albani and Mario Barbatti and Lea M. Ibele},
howpublished = {ChemRxiv},
year = {2026},
month = oct,
doi = {10.26434/chemrxiv.15010274/v1},
url = {https://chemrxiv.org/doi/full/10.26434/chemrxiv.15010274/v1},
note = {CC BY},
}
RIS
TY - UNPB
TI - Solvent Dynamics and Multiconfigurational Treatment Drive the Anomalous Stokes Shift of HINA
AU - Carlo Albani
AU - Mario Barbatti
AU - Lea M. Ibele
PY - 2026
DA - 2026/10/12
PB - ChemRxiv
DO - 10.26434/chemrxiv.15010274/v1
UR - https://chemrxiv.org/doi/full/10.26434/chemrxiv.15010274/v1
AB - The 3-hydroxyisonicotinaldehyde (HINA) anion is one of the smallest known green-emissive fluorophores, yet the origin of its anomalously large Stokes shift (0.87 eV) remains unexplained. Given the well-established influence of the surrounding environment on the photophysical properties of fluorescent dyes, we examine its role in this shift by simulating the anion's absorption and emission spectra with four computational protocols that differ in configurational sampling, solvent treatment, and electronic-structure method. Wigner sampling protocols capture less than half of the experimental Stokes shift, whether the solvent is treated implicitly or explicitly, whereas QM/MM molecular dynamics sampling improves it significantly. Structural analysis associates this improvement with coupling between the first solvation shell and the intramolecular interaction between the aldehyde hydrogen and the hydroxyl oxygen, which is captured by molecular-dynamics sampling but not by the corresponding frozen-solute Wigner-sampling protocol. When combined with RMS-CASPT2, this sampling quantitatively reproduces the experimental spectra and Stokes shift (0.85 versus 0.87 eV), showing that quantitative description of the Stokes shift of HINA requires both solvent-induced conformational dynamics and a multiconfigurational electronic-structure treatment.
ER -