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Photobases Paper Revised.pdf (8.94 MB)
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Structure-Photochemical Function Relationships in Nitrogen-Containing Heterocyclic Aromatic Photobases Derived from Quinoline

preprint
revised on 12.02.2020 and posted on 13.02.2020 by Sophya Alamudun, Kyle Tanovitz, April Fajardo, Kaitlind Johnson, Andy Pham, Tina Jamshidi Araghi, Andrew Petit

Photobases are compounds which become strong bases after electronic excitaton into a charge-transfer excited state. Recent experimental studies have highlighted the photobasicity of the 5-R quinoline compounds, demonstrating a strong substituent dependence to the pKa*. Here we describe our systematic study of how the photobasicity of four families of nitrogen-containing heterocyclic aromatics are tuned through substituents. We show that substituent position and identity both significantly impact the pKa*. We demonstrate that the substituent effects are additive and identify many disubstituted compounds with substantially greater photobasicity than the most photobasic 5-R quinoline compound identified previously. We show that the addition of a second fused benzene ring to quinoline, along with two electron-donating substituents, lowers the vertical excitation energy into the visible while still maintaining a pKa* > 14. Overall, the structure-function relationships developed in this study provide new insights to guide the development of new photocatalysts that employ photobasicity.

Funding

NSF XSEDE allocation TG-CHE180057

History

Email Address of Submitting Author

apetit@fullerton.edu

Institution

California State University, Fullerton

Country

United States of America

ORCID For Submitting Author

0000-0002-9428-3499

Declaration of Conflict of Interest

No conflict of interest

Version Notes

Revised version of the manuscript.

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