Submission Date

7-24-2020

Document Type

Paper- Restricted to Campus Access

Department

Chemistry

Faculty Mentor

Ryan Walvoord

Comments

Presented during the 22nd Annual Summer Fellows Symposium, July 24, 2020 at Ursinus College.

A related presentation is available here.

Project Description

Fluorescent probes have continually been an important field of study and are widely used across many fields of science, including the detection of molecules in biological systems. The most common probes work through a 'turning on' mechanism in the presence of a specific analyte. This 'turn on' feature of fluorescent probes occurs via Photoinduced Electron Transfer (PET), wherein a donor group transfers an electron to the excited fluorophore and prevents it from emitting. Typically, interaction of the probe with its analyte causes an alteration of the donor energy, inhibiting electron transfer and increasing in brightness. This brightness is indicated by the quantum yield, the ratio of the number of photons emitted to the number of photons absorbed. The overarching goal throughout this study is to determine if calculations of O/S/Se-based donors can be used to predict quantum yield and the “ON” / “OFF” state of fluorescent molecules. A variety of coumarin fluorophores with donors of varying electronics are proposed for synthesis. The energy (EHOMO) of each donor is calculated via Spartan computational software and additional molecules are proposed to address energy gaps in the proposed synthetic library. Additionally, a literature search for PET fluorogenic probes with O/S/Se-based donors was performed. Chemical structures and quantum yields were compared with computationally calculated EHOMO energies for each donor. Preliminary results indicate analysis of both acceptor and donor electronics is more effective than calculated EHOMO alone for predicting quantum yield.

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