Ionic liquids based on quaternary phosphonium cation as active components of solid-state iodide selective electrode

Area of Science:

• Electrochemistry
• Materials Science
• Analytical Chemistry

Background:

• Solid-state ion-selective electrodes (ISEs) are crucial for electrochemical analysis.
• Ionic liquids (ILs) offer unique properties as sensing materials.
• Developing robust and selective ISEs for iodide detection remains an area of interest.

Purpose of the Study:

• To develop novel solid-state ion-selective electrodes (ISEs) for iodide sensing.
• To investigate the performance of ionic liquids as active components in ISEs.
• To evaluate the impact of a cobalt phthalocyanine complex on sensor characteristics.

Main Methods:

• Two ionic liquids (ILs) with quaternary phosphonium cations and fluorinated anions were synthesized.
• Solid-state screen-printed electrodes were coated with molten and solidified ILs.
• The ion-sensing layer was further modified with tetrakis(tert-butyl)phthalocyaninatocobalt (III) iodide.

Main Results:

• The developed ISEs demonstrated a clear potentiometric response to iodide ions.
• The addition of the cobalt phthalocyanine complex significantly improved sensor performance.
• The optimized ISE exhibited high sensitivity (S=-(58.0 ± 0.8) mV/dec), a low detection limit (C(min)=6 × 10(-5) M), a rapid response time (ca. 15s), and excellent selectivity over other anions.

Conclusions:

• Ionic liquids, particularly when modified with specific complexes, are effective active components for solid-state ISEs.
• The developed iodide-selective electrode shows promising analytical performance characteristics.
• The sensor maintained stable performance for at least one month, indicating good operational durability.