Luminescence Lifetime-Based Water Conductivity Sensing Using a Cationic Dextran-Supported Ru(II) Polypyridyl Complex

Area of Science:

• Materials Science
• Analytical Chemistry
• Environmental Science

Background:

• Electrical conductivity sensors suffer from electrode corrosion and signal drift during prolonged in situ use.
• Existing methods lack contactless sensing and remote readout capabilities.
• Need for robust, stable, and accurate water conductivity monitoring solutions.

Purpose of the Study:

• To develop a novel, contactless water conductivity sensor.
• To utilize a microenvironment-sensitive ruthenium complex for sensing.
• To overcome limitations of traditional electrical conductivity measurements.

Main Methods:

• Embedding a ruthenium complex, [Ru(2,2'-bipyridine-4,4'-disulfonato)3]4-, into a functionalized polymer support.
• Measuring changes in luminescence emission lifetime correlated with polymer swelling.
• Correlating polymer swelling degree with water conductivity.

Main Results:

• The sensor demonstrated reversible response within 2-3 minutes.
• Stable performance was observed for over 65 hours in KCl solutions (0.8-12.8 mS cm-1).
• Response was largely independent of cation type but sensitive to anion type, dissolved O2, and temperature.

Conclusions:

• The developed sensor offers a promising alternative to electrical conductivity measurements.
• Luminescence lifetime-based detection provides advantages for in situ and remote monitoring.
• Further corrections for environmental factors like O2 and temperature are necessary for precise measurements.