TY - JOUR

T1 - Concept for Water Detection in Organic Solvents via Halogen-Bond-Donor-Mediated UV-Vis Spectroscopic Titration

AU - Путнин, Иван Олегович

AU - Коваленко, Алексей Валерьевич

AU - Сысоева, Александра Александровна

PY - 2025/12/8

Y1 - 2025/12/8

N2 - Abstract: A novel, reagent-efficient spectrophotometric approach for detecting trace water in organic solvents is presented, exploiting competitive halogen bonding (XB) between the iodonium-based σ-hole donating diphenyliodonium triflate, the azo-dye methyl orange, and water molecules. Unlike conventional Karl Fischer titration, this strategy leverages the distinct spectroscopic response arising from preferential complexation of water molecules by the XB donor: UV-vis titration studies in acetonitrile reveal that water saturates the electrophilic σ-hole of the iodonium cation at concentrations up to ~70 equivalents, inhibiting dye coordination. Subsequent addition of diphenyliodonium triflate triggers a sharp, concentration-dependent chromogenic shift, signaling water depletion and formation of the iodonium cation∙∙∙methyl orange charge-transfer complex. This sequence—validated by 1H NMR titration and DFT calculations—enables the visual and spectroscopic identification of water. The study establishes a fundamental concept for moisture sensing, demonstrating operational simplicity and potential for dipstick adaptation. This XB-mediated strategy offers a promising foundation for the future development of alternative moisture detection tools for applications in synthesis, pharmaceuticals, and quality control.

AB - Abstract: A novel, reagent-efficient spectrophotometric approach for detecting trace water in organic solvents is presented, exploiting competitive halogen bonding (XB) between the iodonium-based σ-hole donating diphenyliodonium triflate, the azo-dye methyl orange, and water molecules. Unlike conventional Karl Fischer titration, this strategy leverages the distinct spectroscopic response arising from preferential complexation of water molecules by the XB donor: UV-vis titration studies in acetonitrile reveal that water saturates the electrophilic σ-hole of the iodonium cation at concentrations up to ~70 equivalents, inhibiting dye coordination. Subsequent addition of diphenyliodonium triflate triggers a sharp, concentration-dependent chromogenic shift, signaling water depletion and formation of the iodonium cation∙∙∙methyl orange charge-transfer complex. This sequence—validated by 1H NMR titration and DFT calculations—enables the visual and spectroscopic identification of water. The study establishes a fundamental concept for moisture sensing, demonstrating operational simplicity and potential for dipstick adaptation. This XB-mediated strategy offers a promising foundation for the future development of alternative moisture detection tools for applications in synthesis, pharmaceuticals, and quality control.

KW - UV-vis titration

KW - determination of water traces

KW - halogen bond donor

KW - methyl orange

KW - σ-hole donor

UR - https://www.mendeley.com/catalogue/578c9801-76b8-3255-b3f1-f3bb6d4624a0/

U2 - 10.1134/S1070363225605289

DO - 10.1134/S1070363225605289

M3 - Article

VL - 95

SP - 3467

EP - 3473

JO - Russian Journal of General Chemistry

JF - Russian Journal of General Chemistry

SN - 1070-3632

IS - 11

ER -