Lifetime-based pH sensor system based on a polymer-supported ruthenium(II) complex

Area of Science:

• Materials Science
• Analytical Chemistry
• Photochemistry

Background:

• Development of robust and sensitive pH sensors is crucial for various scientific applications.
• Luminescence-based sensors offer advantages in non-invasive and real-time monitoring.
• Ruthenium complexes are known for their photophysical properties suitable for sensing applications.

Purpose of the Study:

• To describe a new luminescence lifetime-based pH sensor system.
• To develop a sensor utilizing a specific ruthenium complex immobilized in a polymer matrix.
• To evaluate the sensor's performance, including its pH range, sensitivity, and stability.

Main Methods:

• Immobilization of [Ru(Ph2phen)2DCbpy]2+ in a mixed domain network copolymer of poly(ethylene oxide).
• Utilizing hydrophobic domains for irreversible binding of the metal complex.
• Characterizing the pH dependence of the luminescence lifetime and oxygen quenching sensitivity.

Main Results:

• The sensor exhibits a 3-4 fold pH dependence of its luminescence lifetime.
• A usable pH range of approximately 3-5 was achieved.
• The system demonstrated simplified measurements due to long excited-state lifetime and visible absorption.
• A model for combined pH and oxygen-quenching sensitivity was provided, enabling use across various oxygen concentrations.

Conclusions:

• The described polymer-based sensor is easy to prepare and requires no covalent chemistry.
• The polymer matrix enhances luminescence and minimizes oxygen quenching interference.
• This luminescence lifetime-based system provides a stable and effective method for pH sensing.