Degree Name

Master of Science (MS)

Semester of Degree Completion

2017

Thesis Director

Hongshan He

Abstract

For many decades, fluorophores have been used to investigate natural systems, but autofluorescence and photobleaching diminish the detection capacity. Recently, BODIPY based lanthanide complexes have been synthesized and their photophysical properties have been investigated. These complexes exhibit higher emission efficiencies at NIR region with longer NIR lifetimes upon exciting at longer wavelength.

In this study, two BODIPY based lanthanide complexes were synthesized and their photophysical properties were evaluated. BODIPY based ligands were synthesized with phenanthroline as the ligand binding group. These ligands exhibit strong absorption at 527 nm and 532 nm, fluorescence at 540 nm and 548 nm with 0.55 (±0.01) and 0.78 (±0.06) quantum yields. Upon exciting at 525 nm and by titrating with [Yb(TPP)(OAc)(MeOH)2], both ligands formed 1:1 ligand to metal complexes exhibiting strong NIR emissions at 977-1006 nm with two characteristic peaks correspond to unique Yb(III) transition between 2F5/2 ground state and 2F7/12 excited state ofBODIPY based Yb(III) porphyrin complex.

The para substituted aromatic ring containing BODIPY demonstrated 4.97 ns excited state lifetime and the ortho substituted aromatic ring containing BODIPY demonstrated 7.56 ns in the visible region. In contrast, complex 1 and complex 2 possessed 12.24 μs and 8.86 μs respectively. Excitation scan of both complexes showed the evidence of higher excitations at 440 nm and 525 nm suggesting both porphyrin and BODIPY moieties contribute for the lanthanide sensitization process. Further studies are required to address the underline chemistry behind the energy transfer mechanism of both complexes and how the geometry of formed lanthanide complexes affect the sensitization process.

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