Doctor of Philosophy, Miami University, 2025, Chemistry and Biochemistry

The purpose of this dissertation is to observe physical properties of molecules in solution. Structural dynamics information is provided for three systems: a cobalt-centered complex converting between three coordination states at low temperature, a lanthanide complex adopting two NMR-active enantiomers according to identity of the metal center, and a chaperone protein interaction determining binding symmetry. These systems are investigated using a variety of analytical methods – including crystallography, NMR spectroscopy, Density Functional Theory calculations, and Molecular Dynamics simulations. Chapter 2 examines the dynamics of TpPh,Me Cobalt (II) NO3 (TpPh,MeCoNO3) [TpPh,Me = tris-3-phenyl-5-methylpyrazolylborate]. Solid-state XRD structure of TpPh,MeCoNO3 is presented for the first time, showing a five-coordinate Co (II) complex with TpPh,Me with NO3 bound as a bidentate ligand. Variable temperature NMR spectra are complicated at low temperature, with signals coalescing as temperature is increased. The high temperature NMR spectra indicate a four-coordinate structure above room temperature. Spectral analysis demonstrates the TpPh,MeCoNO3 complex occupies three concurrent structures at low temperatures. These three structures are analyzed using Density Functional Theory (DFT) calculations of four- and five-coordinate structures generated in silica from the crystal structure. In Chapter 3, the conformational interconversion of two NMR-active LnDOTAM structures (Ln=La-Lu; DOTAM=1,4,7,10-tetrakis(acetamido)-1,4,7,10-tetraaza-cyclododecane) are examined using a series of 13 lanthanide ions. Variable-temperature 1H NMR spectra demonstrate the concentration of the two identifiable conformations in solution depends on the identity of the metal ion. At low temperature, early LnDOTAM (Ce-Nd) have a high concentration of the twisted square antiprismatic geometry (TSAP), and later LnDOTAM (Sm, Eu, Tb-Yb) have a higher concentration of the square antiprismatic geomet (open full item for complete abstract)

Committee: David Tierney (Advisor); Rick Page (Committee Chair); Michael Crowder (Committee Member); Dominik Konkolewicz (Committee Member); Luis Actis (Committee Member) Subjects: Chemistry; Inorganic Chemistry; Molecular Biology; Physical Chemistry

Master of Science, The Ohio State University, 2024, Chemistry

Both C(sp3)-H fluorination and C(sp3)-H methylation methods have increasingly gathered interest over the last decade. Most current fluorination methods use electrophilic fluorine reagents such as NFSI or Selectfluor to achieve C(sp3)-F bond formation. However, there are limited reports that harness nucleophilic fluorine sources to form such bonds. On the other hand, while there exist “state-of-the-art” methods for C(sp3)-H methylation, there are no reported examples of high-valent copper complexes that can achieve such a transformation. The Zhang lab has synthesized several high-valent copper complexes, most notably a novel LCuIIIF complex (L = PDA) that exhibits dual reactivity of hydrogen atom abstraction (HAA) and fluorine radical capture. Furthermore, in collaboration with the Sevov lab, this complex was employed using electrochemistry to achieve catalytic reactivity in situ to achieve C(sp3)-F bond formation. Despite this, limitations arise, most notably low catalyst turnover due to a sluggish HAA step. Herein, electrochemically generated oxidants were explored to accelerate the HAA step. It was found that LCuIIIOH generated in situ from [LCuIIOH][TBA] helped to lower substrate loading and achieve C(sp3)-H fluorination in high yields, albeit stoichiometrically. In addition, the syntheses of LCuIIICH3 and LCuIIICF2H complexes were explored to use as mechanistic probes for C(sp3)-H functionalization. An efficient route towards obtaining these compounds proceeds through transmetalation of [LCuIIF][TBA] with zinc-based organometallics, followed by oxidation of the isolated [LCuIIR][TBA] (R = CH3, CF2H) salts. It was found that these salts exhibit negative redox couples. Furthermore, LCuIIICF2H exhibits unique reactivity that targets aryl C(sp2)-H bonds.

Committee: Shiyu Zhang (Advisor); Christine Thomas (Committee Member) Subjects: Chemistry

Doctor of Philosophy, The Ohio State University, 2023, Chemistry

Over the past several decades, the noble metals (Au, Pt, Ru, Rh, Pd, Os, and Ir) have proliferated in many industrially relevant processes. With steady growth in world population, increases in anthropogenic climate change, and negative socioeconomic impacts of sustained use of noble metals, the necessity for catalysts based on readily available, earth-abundant frst-row transition metals has grown considerably in recent years. Despite their clear sustainability advantage, the frst-row metals suffer from a reduced proclivity toward the productive two-electron processes upon which the mechanisms of their precious metal counterparts are based. Metal-ligand cooperativity (MLC) has emerged as a strategy to counteract the frst-row metals' propensity toward one-electron processes by appending a non-innocent ligand to the metal center to mitigate the redox burden associated with substrate activation. The MLC examples most relevant to the present work involve activation of substrates across metal–ligand bonds. Often, this activation event brings about a chemical change in the ligand—e.g., the conversion of amides to amines. Herein, substrate activation across the Fe–Namide bond in a square planar S = 1 FeII complex supported by an aryl-linked bis(amido)bis(phosphine) ligand is described. In a previous work, this (PNNP)Fe complex was shown activate B–H bonds across each Fe–N linkage, producing an iron dihydride species that maintained its FeII oxidation state by virtue of MLC. Expanding on this previous result, the work herein reports activation of Si–H and C–H bonds across the Fe–N linkage in addition to functionalization of the Fe–P linkage. Upon treatment of (PNNP)Fe with a slight excess of primary silanes, a unique bridging structure in which two of the Si–H bonds of the primary silanes are activated across the Fe–N bonds of two different (PNNP)Fe units is obtained. Treatment with manifold excess primary silane, however, is shown to result in the formation of a Si–Si bond (open full item for complete abstract)

Committee: Christine Thomas (Advisor); Shiyu Zhang (Committee Member); Christopher Hadad (Committee Member) Subjects: Chemistry

Doctor of Philosophy, The Ohio State University, 2021, Chemistry

Cellular life is naturally orchestrated by the biochemical components of cells that include nucleic acids, lipids, carbohydrates, and proteins. Other vital components include co-factors such as metabolites and transition metals. All of these critical components coalesce inside the cell and function synchronously allowing for complex life. Many natural reactions essential for life require enzymes, several of which require metal co-factors for structural stability or to even mediate the catalytic reaction. These metalloenzymes allow for complex chemical processes, as they catalyze a host of biochemical reactions both efficiently and selectively, where the metal cofactor provides additional functionality to promote reactivity not readily achieved in their absence. The design of miniature enzymes has been explored for over the past sixty years in order to understand the fundamentals of enzyme catalysis and to design more efficient compounds. While mechanistic exploration has illuminated the details of certain catalytic systems, the development of smaller and more efficient catalysts is desired to meet industrial, medical, and environmental needs. Artificial metalloenzymes for glycosidase activity have been investigated previously, however, the development of selective small molecule and peptide-based metalloenzymes have been scarce. Herein, we describe the synthesis, enzymatic characterization, and explore the mechanism of small multi-nuclear copper catalysts as efficient metalloglycosidase mimics. These small molecules appear to mediate degradation of carbohydrate substrates via a CuII/I redox couple with a mainly metal-mediated reaction as very little of the reactive oxygen species (ROS) were diffusible. A synergistic effect is noted when comparing the dinuclear copper system to the mononuclear system in the presence of relevant co-reagents which aid in facilitating the redox reaction. As these complexes can be preferential for glucose and galactose-containing ca (open full item for complete abstract)

Committee: James Cowan (Advisor); Ross Dalbey (Committee Member); Claudia Turro (Committee Member) Subjects: Biochemistry; Chemistry; Inorganic Chemistry

Doctor of Philosophy, The Ohio State University, 2020, Chemistry

There has been an accelerated increase in demand to develop catalysts for renewable energy chemistry, targeting small molecule activation reactions such as N2 fixation, CO2 reduction, and O2 reduction for either harnessing energy or improving the efficiency of energy consumption. Bimetallic complexes recently received strong interest as potential catalyst candidates owing to the unique advantages provided by their multinuclear cores. Particularly, multinuclear cores are designed to process multi-electron redox chemistry that is a prerequisite to small molecule activation, especially when using earth-abundant metal sources to construct catalysts that would allow the development of catalytic performance that is competitive to or even superior to that of expensive and toxic noble metal catalysts that are currently dominating the field. Studying fundamental questions related to bimetallic chemistry, such as metal-metal bonding interactions and metal-substrate interactions has been a focus to help understand metal-metal cooperativity and bimetallic reaction mechanisms. This dissertation is dedicated to the discussion of our recent structural and reactivity studies of C3-symmetric Zr/Co heterobimetallic complexes supported by a tris(phosphinoamide) ligand framework. The small molecule activation capabilities of tris(phosphinoamide) Zr/Co complexes will be discussed. Additionally, organic substrate activations conducted by Zr/Co complexes will be probed, in an effort to both understand their small molecule activation mechanisms, as well as to explore the application of bimetallic complexes in novel reactions to generate value-added products.

Committee: Christine Thomas PhD (Advisor); David Nagib PhD (Committee Member); Shiyu Zhang PhD (Committee Member) Subjects: Chemistry

Doctor of Philosophy, The Ohio State University, 2018, Chemistry

Photon energy fuels life on earth; efforts to better use sunlight for the creation of energy through solar photovoltaics and solar fuels have been of great interest across scientific disciplines. A key factor for using the energy stored in photons is the ability to characterize, to change, and ultimately, to tune the excited states of molecules to absorb wavelengths of light to better harness the solar spectrum while also designing molecules with have excited state energies that are favorable for electron transfer and photocatalytic reactions. This work demonstrates, using Ru(II) and Rh2(II,II) transition metal complexes, the rational synthetic modification of inorganic complexes to better harness low energy wavelengths of the solar spectrum and the tuning of those states to do useful chemical transformations. This is first demonstrated using excited state using Ru(II) complexes, which were explored by small modifications to the ligand geometry in fused donor-acceptor systems using quinone-based electron accepting groups. In this molecule, a side-on geometry was determined to more fully delocalize the electron density on the quinone-containing ligand. This delocalization was determined to both red-shift the absorption to the red (λmax = 546 nm) and increase the excited state lifetime from 0.35 ns to 19 ns. This excited state is capable of performing excited state electron transfer reactions to oxidize phenothiazine, lending the complex to p-type semiconductor applications. These findings outline how small changes to the ligand coordination environment impact the light absorption profile and the excited state dynamics. The effect of synthetic modifications on the excited state properties of transition metal complexes was further explored using dirhodium(II,II) formamidinate complexes. Ultrafast UV-Vis and infrared time-resolved spectroscopy demonstrated the relatively long singlet lifetimes (τS = 7 ps) and 25 ns triplet lifetimes of these complexes, which were then (open full item for complete abstract)

Committee: Claudia Turro (Advisor); Yiying Wu (Committee Member); Anne Co (Committee Member) Subjects: Chemistry; Inorganic Chemistry; Physical Chemistry

Doctor of Philosophy, The Ohio State University, 2017, Chemistry

The class of dirhodium(II,II) complexes [Rh2(µ-BL)2(NN)2][BF4] (µ-BL = DTolF = p-ditolylformamidinate, acam = acetamidate, OAc = acetate; NN = dpq = dipyrido[3,2-f:20,30-h]quinoxaline, dppz = dipyrido[3,2-a:2',3'c]phenazine, dppn = benzo[i]dipyrido[3,2-a:2',3'-h]quinoxaline, phen = 1,10-phenanthroline) were investigated as catalysts for the generation of fuels and useful chemicals from abundant, inexpensive sources. When coupled to a light absorber that can transfer electrons to the Rh2(II,II) complexes, it was hypothesized that they would be able to reduced H+ to H2 and CO2 to molecules useful as fuels or in industry. As such, the ability of these complexes to electrocatalytically reduce each substrate was investigated. When reduced electrochemically, the [Rh2(DTolF)2(NN)2][BF4] (1) complexes were shown to serve as a highly efficient and robust catalysts for the reduction of H+ to H2. Turnover frequencies (TOF) of 2.8 × 104, 2.6 × 104, and 5.9 × 104 s-1 were determined for 1.2, (NN = dppz) 1.3 (NN = dppn), and 1.4 (NN = phen), respectively, with overpotential values of 0.50 (1.2), 0.56 (1.3), and 0.64 V (1.4). Bulk electrolysis followed by headspace injection into a gas chromatograph confirmed the only product to be H2. The proposed catalytic mechanism proceeds through electrochemical generation of a Rh2II,I species that may be protonated to form a Rh2II,III-hydride; the latter undergoes subsequent reduction and protonation to release H2 gas. Complexes 1.1 and 1.4 were shown to also electrocatalytically reduce CO2 in 3 M H2O to produce HCOOH and carbonate. However, ~70% of the electrons in these systems generate H2, such that 1 is not selective for CO2 in the presence of H+. [Rh2(OAc)2(phen)2][BF4] (2) and [Rh2(acam)2(phen)2][BF4] (3) generate greater current enhancement than 1.1 and 1.4 in the presence of CO2 and exhibit significantly different selectivity when compared to 1, with nearly 100% HCOOH production achieved for 3 without degradation. The ca (open full item for complete abstract)

Committee: Claudia Turro (Advisor); Anne Co (Committee Member); James Cowan (Committee Member); David Bromwich (Committee Member) Subjects: Analytical Chemistry; Chemistry; Inorganic Chemistry

Doctor of Philosophy, The Ohio State University, 2005, Chemistry

In this dissertation, various dinuclear organometallic carbonyls (DOCs) – that is, compounds containing two metal atom centers, each bonded to one or more CO ligands – are used to evaluate, both qualitatively and quantitatively, the strengths, weaknesses, possibilities, and limitations of density functional theory (DFT). This evaluation largely concerns itself with the ability of DFT to provide insight and data of relevance to inorganic chemists. The accuracy of DFT as applied to both ground-state and electronically excited-state systems is explored. The first chapter primarily concerns the ability of DFT to distinguish between different isomers of a given molecule, based on both relative stabilities as calculated by DFT and through comparisons between experimentally observed and computationally simulated vibrational absorption spectra. It is shown that calculations of this sort can aid experimental inorganic chemists in a number of ways, including verification of proposed structures, discernment between likely possible structures, and even identification of previously undetermined structures. The accuracy is such that it is even possible to assign the individual infrared peaks of multicomponent systems to their sources. In the second chapter, the precision of DFT is rigorously quantified, using these DOC compounds, and a procedure ideally suited for computational inorganic chemistry is recommended. The following chapter provides similar recommendations for investigations into excited-state chemistry, using the recent methodology of time-dependent density functional theory (TD-DFT). Finally, the procedures are applied to another common DOC, known colloquially as Fp dimer. For this compound, as well as for certain analogues, insight into the complicated solution-phase behavior and photochemistry is afforded through the use of the accurate DFT and TD-DFT approaches explored in the previous chapters. It is expected that the results and recommendations presented herein (open full item for complete abstract)

Committee: Bruce Bursten (Advisor) Subjects:

Master of Science (MS), Bowling Green State University, 2012, Chemistry

One mechanism to achieve photon upconversion, the frequency conversion of low energy photons to those of higher energy, is sensitized triplet-triplet annihilation, a non-coherent (lasers not required) process. In this scheme, a triplet sensitizer is selectively excited at long wavelengths, eventually transferring its triplet energy to an appropriate acceptor molecule in a bimolecular energy transfer reaction. Finally, a second bimolecular energy transfer reaction occurring between two excited triplet acceptors pools the combined energy onto one molecule, producing the fluorescent excited singlet state of the acceptor molecule. This energized molecule radiatively decays back to its ground state releasing photon energies in excess of that of the excitation source, i.e. upconverted with respect to the incident light. This phenomenon has become realized in various combinations of chromophores resulting in wavelength shifting properties that range from the UV to the near-IR. Recently, the upconversion process has become a viable solution to drive fuel-forming chemistry in photoelectrochemical cells and for display applications in polymer host films. The concepts and experiments related to photon upconversion are facile and readily present an opportunity to educate young chemists in this field. Related to established green-to-blue upconversion systems, [Ru(bpy)3](PF6)2 and 9,10-diphenylanthracene (DPA) in deoxygenated dichloromethane is demonstrated here to be a suitable composition for an undergraduate laboratory experiment in physical and/or inorganic chemistry using a conventional fluorimeter. Quadratic incident light power dependence is displayed from the singlet fluorescence of DPA (λem max = 430 nm) resulting from selective excitation of [Ru(bpy)3]2+ at 500 nm using a conventional single photon counting fluorimeter equipped with a 75 W Xe arc lamp. This is easily justified by the fact that two sensitized triplets must be formed in order to ultimately generate the si (open full item for complete abstract)

Committee: Felix Castellano PhD (Advisor); Ksenija Glusac PhD (Committee Member); Peter Lu PhD (Committee Member) Subjects: Chemistry

Doctor of Philosophy, The Ohio State University, 2024, Chemistry

Magnetic molecules have shown promise to be used to understand quantum phenomena for application in quantum computing, magnetic resonance imaging, quantum sensing, and information storage. Magnetic molecules based on electronic spins are extremely sensitive to changes in their local environment, such as nuclear spins. The field has focused on removal of environmental nuclear and electronic spins to lengthen relaxation time. Removal of all nuclear and electronic spins is not feasible for applications. Herein, a series of vanadium (IV) Tris catecholate complexes were chosen to study the impacts of the changes in the local chemistry on magnetic relaxation using nuclear spins and functional groups. Electron paramagnetic resonance (EPR) was used to study spin-lattice relaxation (T1) and phase memory relaxation (Tm). Analysis and fitting of T1 and Tm provided information of how the local environment played a role in shortening these lifetimes. Chapter 1 provides background and motivation for the work discussed in this dissertation. Chapter 2 explores ligand chlorination and counterion impacts at high field/high frequency electron spin relaxation. Chapter 3 presents the impacts of nuclei identity on relaxation time through T1 and  (EPR and susceptibility measurements) and Tm at high field/high frequency. Chapter 4 details noise spectroscopy through CPMG pulsed sequence and provides insight into the solvent cage role in electron spin relaxation time. The findings presented here indicate the importance of local environment and the potential to be able to distinguish the properties of the meal complexes that cause decoherence.

Committee: Joseph Zadrozny (Advisor); Christine Thomas (Committee Member); Caey Wade (Committee Member) Subjects: Chemistry

Master of Science, The Ohio State University, 2020, Chemistry

Organic-inorganic hybrid perovskites have emerged in recent years as one of the most promising materials for solution-processed electronics and optoelectronics including solar cells, light-emitting diodes (LED) and field-effect transistors (FET). Combining the rigid inorganic framework with soft organic materials, these hybrid perovskites provide the opportunity for investigating organic-inorganic interactions at the molecular scale. This MS thesis summarizes studies on organic-inorganic hybrid lead halide perovskites to date, explores PSCs device fabrications and then conducts the synthesis targeting at a new lower-dimensional perovskite incorporating azobenzene. This thesis is organized by exploring the functions of organic cations ranging from structural building block (chapter 2), PSCs device fabrication progress (chapter 3) to the synthesis of azobenzene perovskite (chapter 4). To start the work, experiments were first repeated following established procedure. Then based on these practices, efforts were contributed to new material synthesis. In this process, challenges and problems were tried to be solved and rationalized by various techniques. Finally, synthetic strategy was proposed and conducted based on the rationalized motivation, proposing potential solutions or producing new chemical compounds for found problems.

Committee: Yiying Wu Dr. (Advisor); Patrick Woodward Dr. (Committee Member) Subjects: Chemistry; Electrical Engineering

Doctor of Philosophy, The Ohio State University, 2019, Chemistry

The world's increasing energy consumption puts an enormous demand on non renewable energy sources such as oil and coal. Solar energy is an attractive alternative energy source due to its abundance and small carbon footprint. Unfortunately, current solar harvesting systems are not efficient or cheap enough to completely replace conventional technologies. The search for efficient and affordable solar cells is necessary as world wide energy consumption increases. Time resolved infrared (TRIR) spectroscopy is used in this work to investigate the fundamental photophysics of the photoexcited state of multiple molecular and crystalline systems that have potential to contribute to the world's growing demand in alternative solar harvesting materials. In Chapter 3, dimolybdenum (Mo2) paddlewheel complexes are studied as a highly adaptable class of dyes and potential component in dye sensitized solar cells. Mo2 complexes exhibit unique long lived charge separated metal to ligand charge transfer singlet excited states (1MLCT) which can be monitored with ultrafast resolution with the aid of infrared reporting ligands. When adsorbed onto TiO2, the dye absorbs visible light and fast charge injection occurs from the 1MLCT of the dye to the conduction band of TiO2. In Chapter 4, the charge carrier state of hybrid perovskites are investigated by utilizing different cations as a mid IR excited state probe. Photoexcitation with an energy that exceeds the optical bandgap of these materials produces a broad transient absorption across the mid IR due to free carrier absorption. Positive vibrational absorption features, blue shifted from the ground state are also observed. The solvent stabilization upon photoexcitation of a series of mononuclear tripyrazolylborate iron (III) building block complexes with ancillary TpR ligand is explored in Chapter 5. A relationship is drawn from the electronic structure of the complex to the extent of C≡N stretch weakening in the excited state using TR (open full item for complete abstract)

Committee: Terry Gustafson (Advisor) Subjects: Chemistry

BS, Kent State University, 2019, College of Arts and Sciences / Department of Chemistry and Biochemistry

Group 11 metal (Cu, Ag and Au) amides have proven to have numerous applications in chemistry, some of which are in the areas of nanocrystal synthesis, atomic layer deposition and electronics.[1] Of particular interest is the apparent philicity that the metal centers have to one another. Such interactions lead to otherwise inexplicably short metal-metal distances and interesting molecular geometries.[2] The isolation of five novel metal amido complexes (1 – 5) is described herein. Complexes 1 and 2 were found to exist in the solid-state as planar tetranuclear Cu clusters with alternating dimethylamido (1) or benzamidinate (2) and bis(trimethylsilyl)amido ligands. Complexes 3, 4 and 5 were synthesized using the lithium silylamide generated via the addition of n-butyl lithium to a solution of 1,3-diphenyl-1,1,3,3-tetramethyldisilazane. The lithium amide was subsequently reacted with the corresponding metal (Cu (3), Ag (4) and Au(5)) salt to yield air and light sensitive tetranuclear complexes. Complex 3 was found to contain alternating bis(dimethylphenylsilyl)amide and 1,1-diethyl-3,3-dimethylguanidinate ligands. All five complexes were isolated through evaporation to produce colorless crystals. The compounds were fully characterized using single crystal x-ray diffraction, FT-IR, 1H and 13C NMR. The use of these complexes as precursors for nanocrystals was also investigated. [1] McCain, M. N.; Schneider, S.; Salata, M. R.; Marks, T. J. Inorg. Chem. 2008, 47, 2534-2542. [2] Tsipis, A. C.; Tsipis, C. A. J. Am. Chem. Soc. 2003, 125, 1136-1137.

Committee: Scott Bunge (Advisor); Alexander Seed (Committee Member); Songping Huang (Committee Member); Bjorn Lussem (Committee Member) Subjects: Chemistry; Inorganic Chemistry

PHD, Kent State University, 2018, College of Arts and Sciences / Department of Chemistry and Biochemistry

Iron plays an irreplaceable role in the cell and is found in numerous proteins that use iron as a biological catalyst to perform cell maintenance, growth and cell division. In tumor cells, as well as in normal cellular proliferation, there is a dependence on iron and its availability. With the recognized need to create and test new anti-tumor agents, utilizing the fact that cancer cells disproportionately tend to take up greater amounts of iron than do normal cells, this allows a pathway to be exploited using other metals such as gallium that can interfere in iron metabolism. Gallium ion possesses unique medicinal properties due to its resemblance to iron and is a known mimic of this essential metal. Therefore showing promise for treatment of a variety of diseases and disorders, particularly cancer and bacterial infection due to its antitumorigenic properties and antimicrobial activity. Use of simple soluble inorganic gallium salts, represented by Ganite® for treating a variety of diseases have already reached clinical applications. However, there are still several drawbacks of using gallium salts to deliver gallium at the cellular level, including (1) low-transport capacity of gallium because of the limited plasma concentrations of apo-Tf available for Ga(III)-binding in the blood stream; (2) slow kinetics due to the need to recycle the Tf after the Ga(III) ion is delivered inside the cell; and (3) hydrolysis of Ga(III) ions is a concentration-limiting factor and the origin of renal toxicity of drugs based on soluble gallium salts. To circumvent these limitations of the transferrin-receptor mediated uptake. Gallium nanoparticles with pH sensitivity are synthesized on a PVP (polyvinylpyrrolidone) template for cell culture viability studies on various cancer cell lines. Three gallium-based nanoparticle systems are synthesized and investigated here which confirm cellular uptake in tumorigenic cells and/or cytotoxicity to tumor cells. Effectively bypassing the l (open full item for complete abstract)

Committee: Songping Huang (Advisor); Bansidhar Datta (Committee Member); Mietek Jaroniec (Committee Member); Robin Selinger (Committee Co-Chair); Qi-Huo Wei (Committee Member) Subjects: Biochemistry; Cellular Biology; Chemical Engineering; Chemistry

Master of Science, The Ohio State University, 2017, Chemistry

Cutaneous leishmaniasis (CL) is the most common form of the neglected tropical disease leishmaniasis, causing skin lesions and ulcers on exposed parts of the body often leaving life-long scars and serious disability. This disease is caused by protozoan Leishmania parasites that are transmitted via the bite of infected female phlebotomine sandflies, a species native to tropical regions. With 0.7-1.3 million new annual cases worldwide researchers are investigating new ways of combatting the illness before it progresses to its lethal forms. Photochemical therapy (PCT), more generally known as photodynamic therapy (PDT), has recently become an attractive mode of treatment in various medical fields due to the affordability and efficiency of new light sources and its low invasiveness. Ru(II)-polypyridyl complexes possess a unique combination of chemical stability in solution, strong absorption throughout the UV-vis light regions, and long excited state lifetimes, making them important contributors to this field. Ruthenium complexes containing monodentate N-heterocyclic aromatic ligand and a distortion of the pseudo-octahedral geometry have been shown to undergo ligand dissociation upon irradiation via the population of the metal-centered ligand field (3LF) state from the excited triplet metal-to-ligand charge transfer (3MLCT) state. This presents a mode of photoinduced target drug delivery that can be used to kill the parasites inside the CL infected cells. The following new complexes were synthesized and characterized using ESI-MS and NMR spectroscopy, [Ru(tpy)(bpy)(Q)][PF6]2 and [Ru(tpy)(bpy)(CQ)][PF6]2 (tpy = 2,2':6',2''-terpyridine; bpy = 2,2'-bipyridine; Q = quinoline, and CQ = chloroquinoline, chloroquine). The photochemical properties of ligand dissociation for each of these compounds were investigated and compared; additionally, their photoproducts were identified using NMR photolysis. The complexes possess low quantum yields of ligand exchange, but more importan (open full item for complete abstract)

Committee: Claudia Turro (Advisor); James Cowan (Committee Member) Subjects: Chemistry; Inorganic Chemistry

Master of Science, University of Toledo, 2017, Chemistry

ß-Diketiminates are used as ligands to stabilize metals in various oxidation states, some of which are unstable without the ligand. Although these ligands can stabilize metals in unusual oxidation states, the ligands themselves are not entirely stable as they may undergo nucleophilic attack, reduction/oxidation, rearrangements, or activation of C-H bonds. Similar to ß-diketiminates are dipyrromethenes which are also bidentate, monoanionic ligands used to stabilize a variety of metal complexes. Both ligands form a six-membered ring when chelating to a metal or nonmetal. Although similar, the reactivity and steric bulk of the ligands may differ depending on the substituents attached to the ligand. With no imines present susceptible to nucleophilic attack, it is possible that the reactivity or stability of dipyrromethenes will be completely different from that of ß-diketiminates. Dipyrromethene complexes have already been reported for elements from groups 1, 2, 13, and 14 and various transition metals. The best known commercial application of dipyrromethene complexes is of boron-containing BODIPY dyes used in numerous biological applications due to their tunable optical properties that depend on the substituents attached to the ligand and/or boron. Prior to this work, there were no known dipyrromethene complexes of any group 15 element despite their potential applications in catalysis, organic synthesis, or commercial dyes. The attempted synthesis and characterization of dipyrromethene complexes of phosphorus, antimony, and bismuth are described in this thesis. Chapter 1 is a review of selected bidentate nitrogen-donor ligands and how they relate and compare to dipyrromethenes. Included in this review are ß-diketiminates, diaminonaphthalenes, and dipyrromethenes. Known complexes of group 15 elements are also discussed in this section. The synthesis, coordination behavior and molecular geometry of these compounds are discussed. The synthesis and charact (open full item for complete abstract)

Committee: Mark Mason PhD (Committee Chair); Constance Schall PhD (Committee Member); Joseph Schmidt PhD (Committee Member); Jianglong Zhu PhD (Committee Member) Subjects: Chemistry; Inorganic Chemistry; Organic Chemistry

PhD, University of Cincinnati, 2015, Arts and Sciences: Chemistry

The development of efficient and low-cost catalysts from Earth abundant metals with an objective to replace expensive and precious metal-based catalysts is important for the affordability of commodity chemicals in the future. Therefore, study of nickel based POCOP-pincer hydride complexes as catalysts is of interest due to the use of an abundant metal and the known benefits of the POCOP-pincer ligand such as rigid backbone, high thermal stability and easy to tune the electronic and steric properties. Extensive research of the structure and reactivity of these nickel POCOP-pincer hydride complexes is of great importance to the understanding and development of relatively inexpensive nickel-based catalysts. Progress has been made in three research projects with a unifying theme of hydrogen transfer either from or to nickel POCOP-pincer hydride complexes. Nickel POCOP-pincer hydride complexes react with phenylacetylene to generate two insertion products. The 2,1-insertion is more favorable than the 1,2-insertion and both pathways involve cis addition of Ni–H across the C=C bond. Unlike the palladium case, alkynyl complexes and H2 are not produced in the nickel system. The more bulky hydride complex [2,6-(tBu2PO)2C6H3]NiH shows no reactivity towards phenylacetylene. Catalytic hydrogenation of phenylacetylene with [2,6-(iPr2PO)2C6H3]NiH and [2,6-(cPe2PO)2C6H3]NiH takes place at an elevated temperature (70-100 °C) and proves to be heterogeneous. The structures of the insertion products have been studied by X-ray crystallography. Nickel POCOP-pincer hydride complexes have been found to be active catalysts for dehydrogenation of dimethylamine borane, a viable solid chemically stored hydrogen source. The intermediates and products have been determined by spectroscopic techniques. The homogeneous nickel POCOP-pincer hydride complexes catalyze the dehydrogenation of dimethylamine borane, and heterogeneous nickel particles leached from the POCOP-pincer complexes are (open full item for complete abstract)

Committee: Hairong Guan Ph.D. (Committee Chair); William Connick Ph.D. (Committee Member); James Mack Ph.D. (Committee Member) Subjects: Chemistry

Doctor of Philosophy, The Ohio State University, 2015, Chemistry

The world's ever increasing demand for fossil fuels has lead to a renewed focus by the scientific community to develop energy sources that are clean, renewable, and economical. One of the most promising emerging technologies is photovoltaic cells that can turn sunlight directly into energy or into fuels such as methane or hydrogen. In order for these cells to replace preexisting energy sources, it is necessary to increase their efficiency and processability while also curtailing cost. The focus of this work will be on electron donating materials, the main purpose of which is to absorb light and cause charge transfer to occur in the cell. To increase efficiency of donor materials several factors must be considered. Firstly, the material must capture as much of the solar spectrum as possible, which ranges from 400 nm to well over 1200 nm. Thus a material that has a broad, tunable absorption band is key to capturing as much of this light as possible. Secondly, the absorbing material must efficiently absorb photons by having a high molar absorptivity. Lastly, when light hits the donor material there must be a sufficient separation of the electron-hole pair. The material must stay in this charge separated state long enough to undergo charge transfer to an acceptor and thus begin the circuit. M2 quadruply bonded complexes, where M2 = Mo2, MoW or W2 have optical properties ideal for electron donating materials. Compounds of this type have a fully allowed metal-to-ligand charge-transfer (MLCT) band that is tunable from 400 nm to 1200 nm based on the choice of metal and ligand. This absorption is quite intense with extinction coefficients from 20,000 to nearly 100,000 M-1cm-1. The MLCT is caused by the transfer of an electron from a M2d orbital to a ligand based p* orbital. The molecule exists in this singlet MLCT state for 3 – 25 ps before intersystem crossing to either a 3dd* or 3MLCT state lasting from 2 ns - >75 µs. This work will discuss the synthesis, characteriz (open full item for complete abstract)

Committee: Malcolm Chisholm Ph.D (Advisor); Claudia Turro Ph.D (Committee Member); Patrick Woodward Ph.D (Committee Member) Subjects: Chemistry

Doctor of Philosophy, The Ohio State University, 2009, Chemistry

This work describes the synthesis and characterization of a number of new AA'BB'O6 perovskites which possess the unusual combination of rock salt ordering of B/B' and layered ordering of A/A'. These compounds have been structurally characterized by powder X-ray and neutron diffraction as well as transmission electron microscopy. Several of these compounds are found to adopt polar P21 space group symmetry as a result of the cation ordering in combination with a–a–c+ octahedral tilting. A number of other compounds are shown to have a compositional modulation of the A-site cations that is accompanied by a twinning of the octahedral tilt system. Using UV-Vis spectroscopy the band gaps of these compounds have been determined. This analysis shows that NaLnMgWO6 compounds are insulators while NaLnMnWO6 compounds are semiconductors. The dielectric constants are found to be in the range of approximately 20-35. The magnetic properties of the NaLnMnWO6 and NaLnMgWO6 compounds have been measured. All NaLnMnWO6 compounds are found to order antiferromagnetically at temperatures ranging from 6-15 K. The NaLnMgWO6 compounds do not show any indications of magnetic order. The magnetic structures of NaLaMnWO6, NaNdMnWO6, and NaTbMnWO6 have been determined from neutron powder diffraction. NaLaMnWO6 is found to order into a simple commensurate structure. NaNdMnWO6 orders incommensurately due to interactions between the two magnetic ions. NaTbMnWO6 is found to pass through two magnetic phase transitions. Just below its Neel temperature it has an incommensurate modulation of its structure which disappears as it is further cooled.

Committee: Patrick Woodward PhD (Advisor); Yiying Wu PhD (Committee Member); Malcolm Chisholm PhD (Committee Member) Subjects: Chemistry

Bachelor of Science, Miami University, 2005, College of Arts and Sciences - Biochemistry

A thesis presented on the potential of unique metal complexes, namely Platinum based heterobimetallic paddlewheel complexes, to act as antitumor drugs. The goal of this work is first to present a journal review of currently present platinum and rhodium based antitumor drugs, including cisplatin and di-rhodium complexes which were instrumental in the design of our new proposed antitumor drugs. This will be followed by an introduction to the research I am currently performing in synthesizing these Pt-based heterobimettalic complexes. Finally, results and discussion of my current research findings will be presented. I hope that this work will be both informative and enjoyable to the reader.

Committee: Hong-Cai Zhou (Advisor) Subjects: Chemistry, Inorganic