Highly Selective Electrochemiluminescence Chemosensor for Sulfide Enabled by Hierarchical Reactivity

Area of Science:

• Analytical Chemistry
• Chemical Sensing
• Materials Science

Background:

• Hydrogen sulfide (H₂S) is a toxic gas requiring sensitive detection methods.
• Existing electrochemiluminescence (ECL) sensors for H₂S lack selectivity in aqueous media.
• Development of homogeneous ECL probes with high H₂S selectivity is needed.

Purpose of the Study:

• To develop a novel homogeneous ECL chemodosimetric probe for selective H₂S detection.
• To distinguish H₂S from biothiols using differential reaction kinetics.
• To create an analytical system with improved selectivity and sensitivity compared to fluorescence methods.

Main Methods:

• Design and synthesis of an iridium(III) complex featuring two 7-nitrobenz-2-oxa-1,3-diazol-4-yl (NBD) groups.
• Utilizing photo-induced electron transfer quenching and differential NBD group cleavage for H₂S detection.
• Employing an ECL platform to minimize background signals and enhance selectivity.

Main Results:

• The probe demonstrated high selectivity for H₂S over biothiols due to distinct NBD cleavage rates.
• Achieved a low limit of detection (LOD) of 57 nM for H₂S with a rapid reaction rate.
• Successfully quantified H₂S in real-world samples like tap water and ammonium sulfide solutions.

Conclusions:

• The developed iridium(III) complex-based probe provides a selective and sensitive method for H₂S detection in aqueous environments.
• This ECL chemodosimetric system overcomes limitations of fluorescence-based methods, offering superior performance.
• The probe's effectiveness in real samples highlights its potential for practical field monitoring applications.