Excited-State Dynamics of a Substituted Fluorene Derivative. The Central Role of Hydrogen Bonding Interactions with the Solvent

Substituted fluorene structures have demonstrated unusual photochemical properties. Previous reports on the substituted fluorene Schiff base FR0-SB demonstrated super photobase behavior with a ΔpK b of ∼14 upon photoexcitation. In an effort to understand the basis for this unusual behavior, we have...

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Bibliographic Details
Published in:The journal of physical chemistry. B 2021-11, Vol.125 (44), p.12242-12253
Main Authors: Capistran, Briana A, Yuwono, Stephen H, Moemeni, Mehdi, Maity, Soham, Vahdani, Aria, Borhan, Babak, Jackson, James E, Piecuch, Piotr, Dantus, Marcos, Blanchard, G. J
Format: Article
Language:English
Subjects:
B: Liquids
Chemical and Dynamical Processes in Solution
Fluorenes
Hydrogen Bonding
Schiff Bases
Solvents
Spectrometry, Fluorescence
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Summary:Substituted fluorene structures have demonstrated unusual photochemical properties. Previous reports on the substituted fluorene Schiff base FR0-SB demonstrated super photobase behavior with a ΔpK b of ∼14 upon photoexcitation. In an effort to understand the basis for this unusual behavior, we have examined the electronic structure and relaxation dynamics of the structural precursor of FR0-SB, the aldehyde FR0, in protic and aprotic solvents using time-resolved fluorescence spectroscopy and quantum chemical calculations. The calculations show three excited singlet states in relatively close energetic proximity. The spectroscopic data are consistent with relaxation dynamics from these electronic states that depend on the presence and concentration of solvent hydroxyl functionality. These results underscore the central role of solvent hydrogen bonding to the FR0 aldehyde oxygen in mediating the relaxation dynamics within this molecule.
ISSN:1520-6106
1520-5207
1520-5207
DOI:10.1021/acs.jpcb.1c06474