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New Fluorescent Probes, Their Spectroscopic Properties, and an Iterative Analysis of Their Complexation with
Monika Topa-Skwarczyńska1, Patryk Szymaszek1, Anna Chachaj-Brekiesz2
1Cracow University of Technology, Faculty of Chemical Engineering and Technology, Warszawska 24, 31-155 Kraków, Poland.
The Journal of Physical Chemistry. B
|February 3, 2026
Summary
Substituted pyridylcoumarins form 1:1 host-guest complexes with sulfobutylated beta-cyclodextrin (Captisol). Association constants decrease with electron-withdrawing substituents, indicating interactions with positively charged cyclodextrin sites.
Area of Science:
- Supramolecular Chemistry
- Organic Chemistry
- Photochemistry
Background:
- Coumarin derivatives exhibit diverse photophysical properties.
- Cyclodextrins are widely used hosts for molecular encapsulation.
- Understanding host-guest interactions is crucial for molecular recognition and drug delivery.
Purpose of the Study:
- To characterize the spectroscopic properties of substituted 7-phenylamino-3-(2-pyridyl)coumarins.
- To evaluate the host-guest inclusion complex formation with cyclodextrins.
- To determine and analyze host-guest association constants.
Main Methods:
- Spectroscopic characterization of pyridylcoumarin derivatives.
- Host-guest complexation studies using sulfobutylated β-cyclodextrin (Captisol).
- Determination of association constants using an iterative data workup method, addressing limitations of the Benesi-Hildebrand method.
Main Results:
- Pyridylcoumarins form stable 1:1 host-guest complexes with Captisol.
- Association constants range from 17-122 dm³ mol⁻¹, influenced by substituent electronic properties.
- A decrease in association constant correlates with increased electron-withdrawing substituents, suggesting interaction with positively charged sites in the cyclodextrin cavity.
Conclusions:
- Substituted pyridylcoumarins are effective guests for Captisol, forming well-defined inclusion complexes.
- The electronic nature of substituents significantly modulates the binding affinity.
- An iterative data analysis method provides a robust alternative for determining host-guest association constants, applicable beyond the Benesi-Hildebrand equation.
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