Publication Date

2016

Document Type

Dissertation/Thesis

First Advisor

Adler, Marc Jordan, 1981-

Degree Name

M.S. (Master of Science)

Department

Department of Chemistry and Biochemistry

LCSH

Chlorophenols||Fluorine compounds--Phylogeny--Molecular aspects

Abstract

Flavanone and its ortho-hydroxychalcone isomer can be interconverted by changes in pH, making an attractive molecular switch scaffold. The ortho-hydroxychalcone, being an extended aromatic system, can also be utilized as a fluorophore with metal binding capacity. The scaffold can also be dramatically changed from previous studies by exchanging the acetophenone and benzaldehyde derived rings for hetero and extended aromatic rings to determine their effect on the midpoint pH. A variety of methoxy-/fluoro-substituted and hetero-/extended aromatic chalcones were screened in methanol and pH 13.50 buffer to determine if the scaffolds were fluorescent. From a possible 32 chalcones in the two conditions, 18 neutral and 16 anionic species had observable fluorescence (signal > 19,000). The scaffold, regardless of charge, had very large Stokes shifts often exceeding 100 nm. Several interesting substitution patterns emerged where 5'-substitution of the scaffold seemed to enhance fluorescent signal. The two brightest fluorophores 5',4- and 5',3-dimethoxychalcones, both in methanol, were both substituted at this position. The 4-substitution also showed enhanced fluorescence in pH 13.50 buffer, making it an intriguing high pH sensing fluorophore. Up to this point, the phenyl rings of the ortho-hydroxychalcone flavanone (OHC-Fla) switch were thought to be essential to the equilibrium of the switch. It was shown that replacing these moieties did not affect the viability of the switch and as a result of these studies the lowest and highest midpoint pH values to date were achieved. The switch has shown itself to be robust, reliable, and predictable in spite of large structural modifications.

Comments

Advisors: Marc J. Adler; James R. Horn.||Committee members: Timothy J. Hagen.||Includes bibliographical references.||Includes illustrations.

Extent

vii, 132 pages

Language

eng

Publisher

Northern Illinois University

Rights Statement

In Copyright

Rights Statement 2

NIU theses are protected by copyright. They may be viewed from Huskie Commons for any purpose, but reproduction or distribution in any format is prohibited without the written permission of the authors.

Media Type

Text

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