Enhanced Quenching in an Azaphthalocyanine-Ferrocene Supramolecular Dyad upon Charge-Transfer Complex Formation
Jana Lapesova1, Jiri Demuth1, Veronika Novakova1
1Department of Pharmaceutical Chemistry and Pharmaceutical Analysis, Faculty of Pharmacy in Hradec Kralove, Charles University, Akademika Heyrovskeho 1203 50005 Hradec Kralove, Czech Republic.
Inorganic Chemistry
|December 15, 2025
Summary
Researchers developed a supramolecular strategy to improve fluorescence quenching in azaphthalocyanine dyes. This method enhances charge-transfer complex formation for better photophysical control in applications like photodynamic therapy (PDT) and sensing.
Area of Science:
- Supramolecular Chemistry
- Photochemistry
- Materials Science
Background:
- Azaphthalocyanines (AzaPc) are fluorescent dyes and photosensitizers with potential in photodynamic therapy (PDT) and fluorescence sensing.
- Precise control over AzaPc photophysical properties, particularly fluorescence quenching, is a significant challenge.
- Supramolecular chemistry offers a route to modulate molecular interactions and enhance specific functions.
Purpose of the Study:
- To develop a supramolecular approach for enhanced fluorescence quenching in azaphthalocyanine derivatives.
- To investigate charge-transfer complex formation as a mechanism for fluorescence modulation.
- To design and synthesize novel AzaPc derivatives and quencher molecules for improved sensing and PDT applications.
Main Methods:
- Synthesis of an electron-deficient azaphthalocyanine derivative with a naphthalene-2,6-diol moiety.
- Design and synthesis of a ferrocene-methylviologen conjugate as a dual-function quencher and acceptor.
- Evaluation of fluorescence quenching efficiency in acetonitrile using Stern-Volmer analysis.
Main Results:
- The synthesized AzaPc derivative showed fluorescence quenching upon interaction with the ferrocene-methylviologen conjugate.
- The conjugate quencher demonstrated significantly enhanced quenching efficiency compared to individual components.
- Nonlinear Stern-Volmer dependence indicated both static and dynamic quenching mechanisms, with static quenching (KS = 241 M-1) being dominant due to directed charge-transfer complex formation.
Conclusions:
- Supramolecular complexation effectively enhances the fluorescence quenching of azaphthalocyanine derivatives.
- Directed charge-transfer complex formation is a viable strategy for modulating photophysical properties.
- This approach provides a general method for designing responsive photosensitizers for smart PDT and molecular sensing systems.
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