Aryne-Enabled Synthesis of 1,8-Disubstituted Thioxanthones for Conformationally Gated Metal-Ion Sensing
Abstract
Conformational changes in a chromophore can strongly influence its fluorescence properties. Here, we report the development of thioxanthone-based fluorescent sensors designed to suppress the characteristic butterfly-like deformation of the thioxanthone core upon metal-ion binding. To access the required 1,8-disubstituted scaffolds, we developed an efficient aryne-based synthesis of multisubstituted thioxanthones from readily available o -iodoaryl triflates and N , N , N’ , N’- tetramethylthiourea. Subsequent functionalization provided a series of thioxanthones bearing metal-coordinating substituents at the 1,8-positions. Evaluation of the resulting compounds identified a probe exhibiting pronounced and spectrally distinct fluorescence responses to Zn 2+ and Ca 2+ with high ON/OFF ratios, enabling clear discrimination between the two metal ions. Time-dependent DFT (TD-DFT) calculations for a simplified Zn 2+ complex indicated that coordination stabilizes a nearly planar thioxanthone structure and enhances the oscillator strength of the emissive transition. These results demonstrate the utility of controlling the butterfly-like deformation of the thioxanthone core for metal-ion-responsive fluorescence sensing.
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BibTeX
@misc{arakaki2026aryneenabled,
title = {{Aryne-Enabled Synthesis of 1,8-Disubstituted Thioxanthones for Conformationally Gated Metal-Ion Sensing}},
author = {Riku Arakaki and Mayu Kawada and Suguru Yoshida},
howpublished = {ChemRxiv},
year = {2026},
month = oct,
doi = {10.26434/chemrxiv.15010518/v1},
url = {https://chemrxiv.org/doi/full/10.26434/chemrxiv.15010518/v1},
note = {CC BY},
}
RIS
TY - UNPB
TI - Aryne-Enabled Synthesis of 1,8-Disubstituted Thioxanthones for Conformationally Gated Metal-Ion Sensing
AU - Riku Arakaki
AU - Mayu Kawada
AU - Suguru Yoshida
PY - 2026
DA - 2026/10/15
PB - ChemRxiv
DO - 10.26434/chemrxiv.15010518/v1
UR - https://chemrxiv.org/doi/full/10.26434/chemrxiv.15010518/v1
AB - Conformational changes in a chromophore can strongly influence its fluorescence properties. Here, we report the development of thioxanthone-based fluorescent sensors designed to suppress the characteristic butterfly-like deformation of the thioxanthone core upon metal-ion binding. To access the required 1,8-disubstituted scaffolds, we developed an efficient aryne-based synthesis of multisubstituted thioxanthones from readily available o -iodoaryl triflates and N , N , N’ , N’- tetramethylthiourea. Subsequent functionalization provided a series of thioxanthones bearing metal-coordinating substituents at the 1,8-positions. Evaluation of the resulting compounds identified a probe exhibiting pronounced and spectrally distinct fluorescence responses to Zn 2+ and Ca 2+ with high ON/OFF ratios, enabling clear discrimination between the two metal ions. Time-dependent DFT (TD-DFT) calculations for a simplified Zn 2+ complex indicated that coordination stabilizes a nearly planar thioxanthone structure and enhances the oscillator strength of the emissive transition. These results demonstrate the utility of controlling the butterfly-like deformation of the thioxanthone core for metal-ion-responsive fluorescence sensing.
ER -