A pH-responsive molecular switch with tricolor luminescence

Area of Science:

• Materials Science
• Analytical Chemistry
• Polymer Chemistry

Background:

• Accurate pH monitoring is crucial in various scientific and industrial applications.
• Existing pH sensors often face limitations in sensitivity, response range, or stability.
• Developing novel fluorescent probes for ratiometric pH sensing remains an active area of research.

Purpose of the Study:

• To develop a new ratiometric pH sensor with broad pH range detection.
• To utilize the unique photophysical properties of poly(N-phenylmaleimide) (PPMI) derivatives for pH sensing.
• To explore the self-assembly of block copolymers as a strategy to enhance sensor performance.

Main Methods:

• Synthesis of PPMI-containing block copolymers.
• Investigation of solvatochromism and tautomerism of PPMI derivatives.
• Utilizing theoretical calculations to predict electronic properties of PPMI tautomers.
• Characterization of fluorescence emission properties and pH response.
• Fabrication of the sensor in versatile device forms.

Main Results:

• The developed sensor exhibits ratiometric fluorescence emission across a wide pH range.
• Strong solvatochromism and tautomerism of PPMI derivatives enable precise pH sensing.
• Theoretical calculations confirmed distinct band gaps for keto, enol, and enolate tautomers.
• Tunable emission, reversible color switching, and high luminescent contrast were achieved.
• Block copolymer self-assembly effectively regulated fluorescence and prevented self-quenching.

Conclusions:

• PPMI-based block copolymers offer an innovative platform for accurate H(+) detection.
• The sensor demonstrates fast response and suitability for versatile device applications.
• Rational molecular design and self-assembly provide a novel approach for advanced fluorescent pH sensors.