Matching Items (4)
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- All Subjects: Ligands
- All Subjects: Quinone
- Creators: Gould, Ian R
- Creators: Moore, Ana
Description
Mitochondria produce most of the ATP needed for the cell as an energy source. It is well known that cellular respiration results in oxidative damage to the cell due to the production of reactive oxygen species (ROS). Mitochondrial dysfunction is believed to contribute to a number of degenerative diseases; because of this the mitochondrial respiratory chain is considered as potential drug target. A few series of idebenone analogues with quinone, pyridinol and pyrimidinol redox cores have been synthesized and evaluated as antioxidants able to protect cellular integrity and, more specifically, mitochondrial function. The compounds exhibited a range of activities. The activities observed were used for the design of analogues with enhanced properties as antioxidants. Compounds were identified which provide better protection against oxidative stress than idebenone, and it is thought that they do so catalytically.
ContributorsArce Amezquita, Pablo M (Author) / Hecht, Sidney M. (Thesis advisor) / Moore, Ana (Committee member) / Rose, Seth (Committee member) / Arizona State University (Publisher)
Created2012
Description
ABSTRACT
Transition metals have been extensively employed to address various challenges
related to catalytic organic transformations, small molecule activation, and energy storage
over the last few decades. Inspired by recent catalytic advances mediated by redox noninnocent
pyridine diimine (PDI) and α-diimine (DI) ligand supported transition metals,
our group has designed new PDI and DI ligands by modifying the imine substituents to
feature donor atoms. My doctoral research is focused on the development of PDI and DI
ligand supported low valent first row metal complexes (Mn, Fe, Co) and their application
in bond activation reactions and the hydrofunctionalization of unsaturated bonds.
First two chapters of this dissertation are centered on the synthesis and
application of redox non-innocent ligand supported low valent iron complexes. Notably,
reduction of a DI-based iron dibromide led to the formation of a low valent iron
dinitrogen compound. This compound was found to undergo a sequential C-H and C-P
bond activation processes upon heating to form a dimeric compound. The plausible
mechanism for dimer formation is also described here.
Inspired by the excellent carbonyl hydrosilylation activity of our previously
reported Mn catalyst, (Ph2PPrPDI)Mn, attempts were made to synthesize second generation
Mn catalyst, which is described in the third chapter. Reduction of (PyEtPDI)MnCl2
furnished a deprotonated backbone methyl group containing Mn compound
[(PyEtPDEA)Mn] whereas reduction of (Ph2PEtPDI)MnCl2 produced a dimeric compound,
[(Ph2PEtPDI)Mn]2. Both compounds were characterized by NMR spectroscopy and XRD
analysis. Hydrosilylation of aldehydes and ketones have been studied using
[(PyEtPDEA)Mn] as a pre-catalyst. Similarly, 14 different aldehydes and 6 different
ii
formates were successfully hydrosilylated using [(Ph2PEtPDI)Mn]2 as a pre-catalyst.
Encouraged by the limited number of cobalt catalysts for nitrile hydroboration, we
sought to develop a cobalt catalyst that is active for hydroboration under mild conditions,
which is discussed in the last chapter. Treatment of (PyEtPDI)CoCl2 with excess NaEt3BH
furnished a diamagnetic Co(I) complex [(PyEtPDIH)Co], which exhibits a reduced imine
functionality. Having this compound characterized, a broad substrate scope for both
nitriles and imines have been investigated. The operative mechanism for nitrile
dihydroboration has been investigated based on the outcomes of a series of stoichiometric
reactions using NMR spectroscopy.
Transition metals have been extensively employed to address various challenges
related to catalytic organic transformations, small molecule activation, and energy storage
over the last few decades. Inspired by recent catalytic advances mediated by redox noninnocent
pyridine diimine (PDI) and α-diimine (DI) ligand supported transition metals,
our group has designed new PDI and DI ligands by modifying the imine substituents to
feature donor atoms. My doctoral research is focused on the development of PDI and DI
ligand supported low valent first row metal complexes (Mn, Fe, Co) and their application
in bond activation reactions and the hydrofunctionalization of unsaturated bonds.
First two chapters of this dissertation are centered on the synthesis and
application of redox non-innocent ligand supported low valent iron complexes. Notably,
reduction of a DI-based iron dibromide led to the formation of a low valent iron
dinitrogen compound. This compound was found to undergo a sequential C-H and C-P
bond activation processes upon heating to form a dimeric compound. The plausible
mechanism for dimer formation is also described here.
Inspired by the excellent carbonyl hydrosilylation activity of our previously
reported Mn catalyst, (Ph2PPrPDI)Mn, attempts were made to synthesize second generation
Mn catalyst, which is described in the third chapter. Reduction of (PyEtPDI)MnCl2
furnished a deprotonated backbone methyl group containing Mn compound
[(PyEtPDEA)Mn] whereas reduction of (Ph2PEtPDI)MnCl2 produced a dimeric compound,
[(Ph2PEtPDI)Mn]2. Both compounds were characterized by NMR spectroscopy and XRD
analysis. Hydrosilylation of aldehydes and ketones have been studied using
[(PyEtPDEA)Mn] as a pre-catalyst. Similarly, 14 different aldehydes and 6 different
ii
formates were successfully hydrosilylated using [(Ph2PEtPDI)Mn]2 as a pre-catalyst.
Encouraged by the limited number of cobalt catalysts for nitrile hydroboration, we
sought to develop a cobalt catalyst that is active for hydroboration under mild conditions,
which is discussed in the last chapter. Treatment of (PyEtPDI)CoCl2 with excess NaEt3BH
furnished a diamagnetic Co(I) complex [(PyEtPDIH)Co], which exhibits a reduced imine
functionality. Having this compound characterized, a broad substrate scope for both
nitriles and imines have been investigated. The operative mechanism for nitrile
dihydroboration has been investigated based on the outcomes of a series of stoichiometric
reactions using NMR spectroscopy.
ContributorsGhosh, Chandrani (Author) / Trovitch, Ryan J. (Thesis advisor) / Seo, Don (Committee member) / Moore, Ana (Committee member) / Arizona State University (Publisher)
Created2018
Description
Many natural and synthetic quinones have shown biological and pharmacological activity. Some of them have also shown anticancer activity. Ubiquinone (CoQ10) which is a natural quinone, is a component of the electron transport chain and participates in generation of ATP (adenosine triphosphate). Cellular oxidative stress is key feature of many neurodegenerative diseases such as Friedreich's ataxia, Alzheimer's disease and Parkinson's disease. The increased generation of reactive oxygen species damages cell membranes and leads to cell death. Analogues of ubiquinone in the form of pyrimidinols and pyridinols, were effective in protecting Friedreich's ataxia lymphocytes from oxidative stress- induced cell death. There were some structural features which could be identified that should be useful for the design of the analogues for cellular protection against oxidative stress. There are quinones such as doxorubicin, daunomycin and topopyrones which have anticancer activity. Here I evaluated topopyrone analogues which poison both topoisomerases I and II. The topopyrone analogues were lethal to human breast cancer cells, but these analogues were not as potent as camptothecin.
ContributorsRaghav, Nidhi (Author) / Hecht, Sidney M. (Thesis advisor) / Gould, Ian R (Committee member) / Williams, Peter (Committee member) / Arizona State University (Publisher)
Created2011
Description
The addition of aminoalkyl-substituted 2,6-bis(imino)pyridine (or pyridine diimine, PDI) ligands to [(COD)RhCl]2 (COD = 1,5-cyclooctadiene) resulted in the formation of rhodium monochloride complexes with the general formula (NPDI)RhCl (NPDI = iPr2NEtPDI or Me2NPrPDI). The investigation of (iPr2NEtPDI)RhCl and (Me2NPrPDI)RhCl by single crystal X-ray diffraction verified the absence of amine arm coordination and a pseudo square planar geometry about rhodium. Replacement of the chloride ligand with an outer-sphere anion was achieved by adding AgBF4 directly to (iPr2NEtPDI)RhCl to form [(iPr2NEtPDI)Rh][BF4]. Alternatively, this complex was prepared upon chelate addition following the salt metathesis reaction between AgBF4 and [(COD)RhCl]2. Using the latter method, both [(NPDI)Rh][BF4] complexes were isolated and found to exhibit κ4-N,N,N,N-PDI coordination regardless of arm length or steric bulk. In contrast, the metallation of PPDI chelates featuring alkylphosphine imine substituents (PPDI = Ph2PEtPDI or Ph2PPrPDI) resulted in the formation of cationic complexes featuring κ5-N,N,N,P,P-PDI coordination in all instances, [(PPDI)Rh][X] (X = Cl, BF4). Adjusting the metallation stoichiometry allowed the preparation of [(Ph2PPrPDI)Rh][(COD)RhCl2], which was characterized by multinuclear NMR spectroscopy and single crystal X-ray diffraction.
ContributorsLevin, Hagit Ben-Daat (Author) / Trovitch, Ryan J (Thesis advisor) / Gould, Ian R (Committee member) / Ghirlanda, Giovanna (Committee member) / Arizona State University (Publisher)
Created2016