Manipulating the electronic properties of metallophthalocyanines through interactions with the ligand's aromatic core

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Thesis type
(Thesis) Ph.D.
Date created
This thesis focuses on manipulating the electronic properties of metallophthalocyanines (MPc). The ring-oxidized, radical zinc phthalocyaninato cation was isolated and structurally characterized. This oxidized ligand underwent hydrogen atom transfer with ether solvents to form a side-pocket protonated zinc phthalocyaninium cation. The ring-oxidized zinc phthalocyaninato combined with zinc phthalocyanine (generated from the hydrogen atom transfer) in solution to form a half-oxidized "pimer", which was a mono-radical dimer, and was characterized by EPR and XRD. Moving to substituted MPcs in order to inhibit aggregation and decrease the ligand oxidation potential, cobalt and copper alpha-octaetherphthalocyanines ((OR)8Pc) were synthesized. Three different butyl groups on the ethers were investigated: n-butyl, iso-butyl, and sec-butyl. Moving from the linear chain to the more steric secondary ether, the first and second ring-oxidation potentials were decreased by ≈70 mV and ≈100 mV for both metals, without significantly shifting the electronic absorptions. Using the n-butyl (OR)8Pc, as well as alpha-octakis(isopropylthio)phthalocyanine ((SR)8Pc) with manganese(III), the position of the Q-band was tuned via axial ligand exchange. Moving from electron-rich to electron-poor axial ligands, as well as 5 to 6-coordinate complexes the Q-band λmax was shifted from 815 nm to 879 nm for the (OR)8Pcs, and from 877 nm to 948 nm for the (SR)8Pcs. This was possible due to the presence of a LMCT-band. This LMCT-band underwent similar shifts to the Q-band, as well as decreases and increases in intensity for electron-rich and electron-poor axial ligands respectively. In the pursuit of synthesizing (OR)8PcZn, a side-pocket protonated zinc alpha-octabutoxyphthalocyaninium chloride was spontaneously generated. This species, as well as similar complexes with an acetate and bisbutoxyphthalimide bound axially in place of the chloride were isolated and structurally characterized. The side-pocket protonation shifted the Q-band absorption to 814 nm, and the emission to 826 nm, with a quantum efficiency of 4%. (OR)8PcZn was then synthesized and isolated by stripping the chloride of the zinc phthalocyaninium chloride with AgSbF6.
260 pages.
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Thesis advisor: Leznoff, Daniel B.
Thesis advisor: Williams, Vance
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