Ionic complex of a rhodamine dye with aggregation-induced emission properties

Area of Science:

• Materials Science
• Biochemistry
• Analytical Chemistry

Background:

• Rhodamine derivatives are widely explored as fluorescent probes.
• Aggregation-caused quenching (ACQ) is a common phenomenon in luminogens.
• Developing stimuli-responsive materials is crucial for sensing applications.

Purpose of the Study:

• To synthesize a novel AIE-active rhodamine-based luminogen.
• To investigate its potential as a luminescent sensor for various analytes.
• To explore its protein denaturation capabilities.

Main Methods:

• Complexation reaction between rhodamine hydrazide (RdH) and camphorsulfonic acid (CSA).
• Characterization of the resultant ionic complex RdH(CSA)_x.
• Evaluation of luminescent properties and sensing capabilities towards metal ions, organic amines, and bovine serum albumin (BSA).

Main Results:

• The complex RdH(CSA)_x exhibits AIE properties, unlike its ACQ counterpart RdH(HCl)₃.
• RdH(CSA)_x demonstrates sensitive luminescence responses to external stimuli, enabling detection of metal ions, organic amines, and BSA.
• The ionic complex RdH(CSA)_x was found to act as a denaturant for BSA, uncoiling its peptide chains.

Conclusions:

• AIE-active rhodamine-based luminogen RdH(CSA)_x was successfully synthesized.
• RdH(CSA)_x serves as a versatile luminescent sensor and a protein denaturant.
• This study highlights the potential of functionalized rhodamine derivatives in advanced sensing and biochemical applications.