Iridium-Based Time-Resolved Luminescent Sensor for Ba²⁺ Detection

Area of Science:

• Analytical Chemistry
• Inorganic Chemistry
• Materials Science

Background:

• Barium ions (Ba²⁺) play roles in various chemical and biological processes.
• Accurate detection of Ba²⁺ is crucial for applications ranging from environmental monitoring to fundamental physics research.
• Existing methods for Ba²⁺ detection may lack the sensitivity or specificity required for certain demanding applications.

Purpose of the Study:

• To introduce a new time-resolved chemosensor for the selective and sensitive detection of barium ions (Ba²⁺).
• To leverage dual luminescence and distinct phosphorescence decay kinetics for signal differentiation.
• To explore the potential application of this sensor in advanced scientific fields, such as neutrinoless double beta decay searches.

Main Methods:

• Development of an iridium(III) compound exhibiting dual fluorescent and phosphorescent emission.
• Investigation of luminescence response (intensity and wavelength) upon chelation with Ba²⁺.
• Time-resolved luminescence spectroscopy to measure phosphorescence decay constants in free and Ba²⁺-bound states.
• Quantum chemical calculations to support experimental observations.

Main Results:

• The chemosensor exhibits suppressed phosphorescence in its free state and enhanced phosphorescence upon binding Ba²⁺.
• Distinct phosphorescence decay times were observed: short for the free sensor (τ_free¹ ≈ 3.5 ns, τ_free² ≈ 209 ns) and long for the Ba²⁺-bound sensor (τ_bound¹ ≈ 429 ns, τ_bound² ≈ 1128 ns).
• Time-based analysis allows for effective separation of signals from free and Ba²⁺-chelated sensor species.

Conclusions:

• The developed iridium(III) chemosensor provides a robust platform for time-resolved Ba²⁺ detection.
• The unique luminescence properties and decay kinetics enable precise discrimination between different sensor states.
• This sensor holds promise for applications requiring sensitive Ba²⁺ detection, including potential use in neutrinoless double beta decay experiments.