Author ORCID Identifier
Semester
Summer
Date of Graduation
2025
Document Type
Dissertation
Degree Type
PhD
College
Eberly College of Arts and Sciences
Department
Chemistry
Committee Chair
Brian Popp
Committee Co-Chair
Carsten Milsmann
Committee Member
Brian Dolinar
Committee Member
Fabien Goulay
Committee Member
Alan Bristow
Abstract
Photosensitizers are vital components to applications such as photoredox catalysis, photodynamic therapy, and various avenues of solar energy production. The abilities of transition metal photosensitizers containing precious metals have been well studied over the years. However, because of the growing scarcity of these metals, there has been a shift in finding more earth abundant alternatives. To help fill this gap in the literature, the Milsmann group has developed and studied the photophysical properties of Zr(IV) complexes with various ligand systems. Due to the electron deficient metal center, these complexes exhibit ligand-to-metal charge transfer (LMCT), unlike the metal-to-ligand charge transfer commonly seen in precious metal complexes. A complex of interest in the group is Zr(MesPDPPh)2, due to its air and water stability and optical properties, including a long-lived excited state (τ=350µs) attributed to thermally activated delay fluorescence (TADF). Zr(MesPDPPh)2 has been used in applications like photon upconversion and photoredox catalysis. While the complex checks multiple boxes for being a good candidate for solar energy applications such as photovoltaics and solar fuels production, its applicability is hindered by insolubility in polar solvents and lack of groups for surface attachment. The aim of this research was to modify Zr(MesPDPPh)2 with polar functional groups in attempt to make it a viable candidate for polar solvent driven applications and solar cell design. Due to the synthetic hindrances of the required zirconium starting material, polar groups had to be installed post metalation. To achieve this, a series of ligands were designed and synthesized with a tertiary amine or various ether-protecting groups. The ligands were used for complex synthesis and deprotection. Ultimately, a combination of the knowledge gained from this research and inspiration from the literature led to the synthesis and isolation of Zr(MesPDPPhOH)2. Two polar functionalized complexes, Zr(MesPDPPhOH)2 and Zr(MesPDPPhNMe3)2·4OTf, were synthesized, and structural and photophysical characterization was obtained. Installation of polar groups led to a drastic increase in polar solvent solubility, while having no effect on the optical properties. The complexes were both capable co-catalysts in photocatalytic CO2 reduction. The deprotected complex, Zr(MesPDPPhOH)2, was further modified to generate the intermediate Zr(MesPDPPhOTf)2. This complex was used for the synthesis of a complex with phosphonate ester anchoring groups, Zr(MesPDPPhPO(OEt)2)2. The anchoring group functionalized complex adheres to silica, has a high quantum yield (φ=0.71), and also exhibits an increased solubility in polar solvents.
Recommended Citation
Tordella, Marisa NIcole, "Introduction of Polar Functional Groups to Pyridinedipyrrolide Zirconium Photosensitizers Through Post-Synthetic Modifications" (2025). Graduate Theses, Dissertations, and Problem Reports. 13024.
https://researchrepository.wvu.edu/etd/13024