Singlet Oxygen Responsive Small Molecules and Polymers.
Altinok, Esra.
2017-04-20T13:56:49.270Z
-
Abstract: Abstract Conjugated polymers are widely used in applications for developing sensory materials. The binding of a single analyte to one of the receptors in conjugated polymer results in an amplified response due to the migration of the exciton on the polymer chain. This amplification of the signal makes the conjugated polymers more advantageous relative to small molecule sensors. This thes... read moreis describes the use of conjugated polymers as well as non-conjugated polymers, mimicking the light harvesting behavior of conjugated polymers, that response to photogenerated singlet oxygen in both organic solvent and aqueous environment. Chapter 2 describes conjugated poly(fluorene-co-phenylene)s (PFs) with 2,5-diarylfuran moieties as nonconjugated pendants that respond to singlet oxygen by fluorescence quenching. By oxidizing the diarylfurans to more electron-poor moieties, singlet oxygen causes poly(fluorene-co-phenylene) conjugated backbones to donate excited electrons to the oxidized pendants, resulting in quenching of up to 93% of the initial fluorescence of the polymer. Chapter 3 describes two-dimensional conjugated poly(phenylene-ethynylene)s (PPEs) linked to singlet oxygen-reactive diethynyltetracene units through phenylene-ethynylene (PE) bridges. Small molecule models of the polymers showed ratiometric responses of fluorescence upon exposure to singlet oxygen. The fluorescent responses of the tetracene-linked PPEs, however, were remarkably different: i) upon exposure to singlet oxygen, fluorescence intensity and fluorescence lifetime of the side-chain tetracenes was increased initially, indicating an analyte-induced slowing of self-quenching due to high local acene concentration, and ii) ratiometric blue-shifted response did not occur until approximately 75% of pendant acenes were oxidized, which highlights the potential utility of analyte-induced removal of traps in light-harvesting fluorescent materials. Chapter 4 describes the design of a system that respond singlet oxygen in water for potential use in bioanalytical applications such as protein sensing. The designed system mimics the light harvesting behavior of CPs, but is prepared with an acrylic polymer formulation that is easier to make water-soluble. The signal transduction mechanism uses 1O2 to communicate the presence of dye-labeled protein to the responsive non-conjugated polymer and prevents proteins from directly interacting with the polymer.
Thesis (Ph.D.)--Tufts University, 2015.
Submitted to the Dept. of Chemistry.
Advisor: Samuel Thomas III.
Committee: Clay Bennett, Arthur Utz, and Shawn Burdette.
Keywords: Chemistry, Organic chemistry, and Polymer chemistry.read less - ID:
- qr46rb84c
- To Cite:
- DCA Citation Guide EndNote
