A rhodamine B-based fluorescent sensor toward highly selective mercury (II) ions detection

Area of Science:

• Chemical Sensing
• Fluorescence Spectroscopy
• Materials Chemistry

Background:

• Mercury (II) ions are highly toxic environmental pollutants.
• Development of sensitive and selective probes for mercury detection is crucial.
• Rhodamine B derivatives are widely used in developing chemosensors due to their favorable photophysical properties.

Purpose of the Study:

• To design and synthesize a novel rhodamine B-based chemosensor (RA) for sensitive and selective detection of mercury (II).
• To investigate the photophysical properties and sensing mechanism of the chemosensor RA towards Hg(2+).

Main Methods:

• Design and synthesis of the rhodamine B-amide derivative (RA).
• X-ray crystal structure analysis to confirm the spirolactone property.
• Photophysical studies including fluorescence and absorption spectroscopy to evaluate sensing performance.
• Selectivity tests with various metal ions.

Main Results:

• The chemosensor RA demonstrated a "turn-on" fluorescence enhancement upon binding with mercury (II).
• A distinct color change from colorless to pink was observed, indicating high visual detection capability.
• The spirolactone ring opening mechanism was confirmed, leading to strong visible absorption.
• Chemosensor RA showed high specificity for Hg(2+) over other common metal ions.

Conclusions:

• The rhodamine B-based chemosensor RA is effective for sensitive and selective detection of mercury (II).
• The observed "turn-on" fluorescence and colorimetric response provide a robust platform for Hg(2+) sensing.
• The X-ray crystal structure analysis provides insights into the sensing mechanism involving spirolactone ring opening.