Submission Date

4-30-2019

Document Type

Paper- Restricted to Campus Access

Department

Chemistry

Adviser

Ryan Walvoord

Committee Member

Eric Williamsen

Committee Member

Nicholas Scoville

Committee Member

Ryan Walvoord

Department Chair

Amanda Reig

Project Description

Fluorescent probes act as valuable chemical tools to detect a variety of substances with exceptional sensitivity and selectivity. One desired property of an effective fluorescent probe is that it acts via a “turn-on” mechanism, in which fluorescence intensity increases upon interaction with the desired analyte. Photoinduced electron transfer (PET) is one of the many mechanisms that is used to modulate photophysical properties of fluorescent probes. In this mechanism, the fluorogenic probes are equipped with a motif that can suppress fluorescence. These probes can undergo a transformation upon interaction with a target molecule that restricts that moiety from quenching the fluorescence, resulting in a fluorescence enhancement. Various probes containing pendant aryl quenching moieties that undergo photoinduced electron transfer have been reported to have a direct correlation between the experimentally determined quantum yield of the probe and the highest occupied molecular orbital (EHOMO) of the corresponding PET quenching moiety. However, the systematic investigation of the relationship between PET-quenching and moieties other than aryl rings has been underdeveloped. By changing the electronics of heteroatom quenching moieties, systematic studies of factors which affect PET for common fluorophores, including coumarin based systems, can be reported. Through the synthesis of 7-MeO-coumarin probes with various quencher functionality, there exists a correlation between the quantum yield of these probes and the molecular orbital energy of the quenching moiety. This study aims to provide the scientific community with tools to design heteroatom PET-based fluorescent sensors a priori.

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