A brief introduction to the current state of research in the Origins of Life field is given in Part I of this work. Part II covers original research performed by the author and co-workers. Layered Double Hydroxide (LDH) systems are anion-exchanging clays that have the general formula M(II)xM(III)(OH)(2x+2)Y, where M(II) and M(III) are any divalent and trivalent metals, respectively. Y can be nearly any anion, although modern naturally occuring LDH systems incorporate carbonate (CO32-), chloride (Cl-), or sulfate (SO42-) anions. Intercalated cobalticyanide anion shows a small yet observable deviation from local Oh symmetry causing small differences between its oriented and non-oriented infrared spectra. Nitroprusside is shown to intercalate into 2:1 Mg:Al LDH with decomposition to form intercalated ferrocyanide and nitrosyl groups of an unidentified nature. The [Ru(CN)6]4- anion is shown to intercalate into layered double hydroxides in the same manner as other hexacyano anions, such as ferrocyanide and cobalticyanide, with its three-fold rotational axis perpendicular to the hydroxide sheets. The square-planar tetracyano-nickelate(II), -palladate(II), and platinate(II) anions were intercalated into both 2:1 and 3:1 Mg:Al layered double hydroxides (LDH). The basal spacings in the 2:1 hosts are approximately 11 Å, indicating that the anions are inclined approximately 75 degrees relative to …

NiSi is an attractive material in the production of CMOS devices. The problem with the utilization of NiSi, is that there is no proper method of cleaning the oxide on the surface. Sputtering is the most common method used for the cleaning, but it has its own complications. Dry cleaning methods include the reactions with radicals and these processes are not well understood and are the focus of the project. Dissociated NF3 and NH3 were used as an alternative and XPS is the technique to analyze the reactions of atomic fluorine and nitrogen with the oxide on the surface. A thermal cracker was used to dissociate the NF3 and NH3 into NFx+F and NHx+H. There was a formation of a NiF2 layer on top of the oxide and there was no evidence of nitrogen on the surface indicating that the fluorine and hydrogen are the reacting species. XPS spectra, however, indicate that the substrate SiO2 layer is not removed by the dissociated NF3 and NiF2 growth process. The NiF2 over layer can be reduced to metallic Ni by reacting with dissociated NH3 at room temperature. The atomic hydrogen from dissociated ammonia reduces the NiF2 but it was determined that the …

The kinetics of the reaction of atomic sulfur with acetylene (S (3P) + C2H2) were investigated experimentally via the flash photolysis resonance fluorescence method, and the theoretical potential energy surface for the reaction CN + SO was modeled via the density functional and configuration interaction computational methods. Sulfur is of interest in modern chemistry due to its relevance in combustion and atmospheric chemistry, in the Claus process, in soot and diamond-film formation and in astrochemistry. Experimental conditions ranged from 295 – 1015 K and 10 – 400 Torr of argon. Pressure-dependence was shown at all experimental temperatures. The room temperature high-pressure limit second order rate constant was (2.10 ± 0.08) × 10-13 cm3 molecule-1 s-1. The Arrhenius plot of the high-pressure limit rate constants gave an Ea of (11.34 ± 0.03) kJ mol-1 and a pre-exponential factor of (2.14 ± 0.19) × 10-11 cm3 molecule-1 s-1. S (3P) + C2H2 is likely an adduct forming reaction due to pressure-dependence (also supported by a statistical mechanics analysis) which involves intersystem crossing. The potential energy surface for CN + SO was calculated at the B3LYP/6-311G(d) level and refined at the QCISD/6-311G(d) level. The PES was compared to that of the analogous reaction …

The tricobalt cluster PhCCo₃(CO)₉ (1) reacts with the bidentate phosphine ligand 2,3-bis(diphenylphosphino)maleic thioanhydride (bta) with added Me₃NO to yield PhCCo₃(CO)₇(bta) (2), which upon heating overnight yields Co₃(CO)₆(μ₂-η²,η¹-C(Ph)C=C(PPH₂)C(O)SC(O)) (μ₂-PPh₂) (3). Cluster (3) has been isolated and characterized by FT-IR and ³¹P NMR spectroscopy. Structural determination of the cluster has been demonstrated by X-ray diffraction analysis. Cluster (3) is analogous to the cluster synthesized by Richmond and coworkers. The redox properties of (3) have been examined by cyclic voltammetry and the data are reported within.

Benzenesulfonates, para-substituted with amine, chloride and methyl groups were successfully incorporated into layered double hydroxides of two different compositions, 2:1 Mg-Al LDH and 2:1 Zn-Al LDH. These parent materials were also doped with small amounts of nickel and the differences in the two systems were studied. The hexamethylenetetramine route of layered double hydroxide synthesis was investigated to verify if the mechanism is indeed homogeneous. This included attempting preparation of 2:1 Mg-Al LDH, 2:1 Zn-Al LDH and 2:1 Zn-Cr LDH with two different concentrations of hexamethylenetetramine. The analytical data of the products suggest that the homogeneous precipitation may not be the true mechanism of reaction involved in LDH synthesis by this method.

The theoretical model of Beratan and Onuchic predicts a large attenuation of ET rates through hydrogen bonds; however, the effect of individual hydrogen bond on electron transfer reaction has not been systematically studied. The organic complexes in this study are a series of crown ether/ammonium salt, which incorporate a redox partner on each component of the complex. The dimethoxynaphthalene redox donor was attached to the crown ether and a series of ammonium salts was synthesized which bear substituted quinone and naphthoquinone acceptor. The complexes characterization and preliminary electron transfer rate measurement were completed with UV/Vis and steady-state emission spectroscopy.

Fluorocarbons are known to be stiffer than their hydrocarbon analogues, a property that underlines the extensive industrial application of fluorocarbon materials. Although there has been previous studies on the rotational barrier of molecules having fluorocarbon centers, a detailed systematic study is necessary to quantify flurocarbon stiffness. The molecules, Pyrene-(CF2)n-Pyrene, Pyrene-(CF2)n-F, Pyrene-(CH2)n-Pyrene and Pyrene-(CH2)n-H were therefore synthesized to enable the determination of the barrier to rotation of the carbon backbone in fluorocarbons. Conformational studies will be completed with steady-state and time-dependent emission spectroscopy.

Reaction of the tetracobalt cluster Co4(CO)10(t 4-PPh)2 with 1,2-bis(dimethylphosphino)ethane (dmpe) affords the bis-substituted cluster Co4(CO)8(dmpe)(t 4-PPh)2. The bidentate dmpe ligand is shown to bind to the cluster in a chelating fashion by IR, NMR, and X-ray diffractions analyses. The fluxional nature of the ancillary carbonyl groups has been studied by variable temperature 13C NMR measurements which reveal two distinct carbonyl scrambling pathways. The stability of the phosphine-ligated cluster has been examined using in situ Cylindrical Internal Reflection (CIR) Spectroscopy. The effect of the dmpe ligand on the cluster polyhedron will be discussed with respect to the observed crystallographic and spectroscopic results

Six bis(silyl)acetylenes with the following varied silicon substituents were prepared: I (Me, Me); II (H, H); III (Cl, H); IV (Cl, Cl); V (OMe, H); VI (OMe, OMe). While I and II may be prepared by the reaction of dilithio- or bis(bromomagnesium)-acetylide with appropriate chlorosilane, similar reactions designed to give III - VI give oligomers, YMe_2Si(C≡C-SiMe_2)_nY, VII, Y = Cl, OMe, as the major products indicating that the acetylenic functionality on silicon activates the chlorosilane toward nucleophilic substitution. Compounds III and IV were prepared by free radical chlorination of II. Methanolysis of III and IV gave quantitative yields of V and VI, respectively. In the presence of mineral acid, VI readily cyclized to give high yields of the cyclic siloxane octamethyl-4,9-dioxa-3,5,8,10-tetrasila-cyclodeca-1,6-diyne, VIII, and the analogous triyne, IX. It was determined that V and VI could be prepared directly from II in high yield by methanolysis with palladium catalyst. Vaska's complex also accomplished the conversion. I attempted to prepare bis(ethoxydimethylsilyl)acetylene by using of Wilkinson 's catalyst for hydrosilylation with acetaldehyde. The principal product of this reaction was 1-(dimethylsilyl)-3,5,5-trimethyl-4-oxa-3-silacyclopent-1-ene, XI.

A variable temperature ^13 C and ^199 Hg NMR study has been conducted for diphenyl-, bis(o-tolyl)-, bis(m-tolyl)-, and bis(2, 6-xylyl)mercury in dimethyl sulfoxide and 1,1,2,2 tetrachloroethane; ^13 C T1 relaxation times are reported as a function of temperature. Barriers to rotation of the aryl rings are obtained. Chemical shifts and couplings in CDCl_3 are given for bis(p-tolyl)-, bis(2, 5-xylyl)-, bis(mesityl)-,phenyl(o-tolyl)-, phenyl(m-tolyl)mercury, and the compounds listed above. The steric interactions of these aryl mercury compounds are discussed.

The structures of Diels-Alder cycloaddition of cyclopentadiene to 2,6-dimethyl-p-benzoquinone and methylcyclopentadiene to 2,6-dimethyl-p-benzoquinone were assigned by analysis of 1-D and 2-D proton and carbon-13 NMR spectra. The structures of the cycloadduct of methylcyclopentadiene to 2,6-dimethyl-p-benzoquinone and that of the corresponding intramolecular [2+2] photocyclization product were also obtained by single crystal X-ray structural analysis. As the second part of the study, a new polycyclic "cage" molecule, a substituted trishomocubane isomer, was synthesized. In this synthesis, reductive bond cleavage followed by Dieckmann condensation was employed. Wolff-Kishner reduction then was used to convert a β-keto ester "cage" molecule to the corresponding carboxylic acid. A compound that possesses twofold symmetry was isolated from reaction product mixture. The structure of this compound has been established by single crystal X-ray crystallography.

The temperature-dependent catalytic activity of rat liver 3-hydroxy-3 -methylglutaryl coenzyme A reductase (HMG-CoA reductase) displays the nonlinear Arrhenius behavior characteristic of many membrane-bound enzymes. A two-conformer equilibrium model has been developed to characterize this behavior. In the model, HMG-CoA reductase undergoes a conformational change from a low specific activity to a high specific activity form. This conformation change is apparently driven by a temperature-dependent phase transition of the membrane lipids. It has been found that this model accurately describes the data from diets including rat chow, low-fat, high-carbohydrate, and diets supplemented with fat, cholesterol or cholestyramine. The effects characterized by the model are consistent with the regulation of HMG-CoA reductase by enzyme-lipid interactions.

Diels-Alder [4+2] cycloaddition of a mixture of 1- and 2 methylcyclopentadiene to 2-phenyl-g.-benzoquinone affords a mixture of four nd cycloadducts. A single, isomerically pure cycloadduct was isolated by careful column chromatography. Stereospecific reduction of this material with sodium borohydride and cerium(III) chloride 'affords a single, isomerically pure tricyclic diol. The structures of the cycloadduct and this tricyclic diol, established via analysis of their one- and two-dimensionial NMR spectra, were shown to be (1-methyl-5-phenyltricyclo[6.2.1.02,7]undec a-4,9 diene-3,6-dione and 1-methyl-5-phenyltricyclo[6.2.1.0 2 ,7 ]undeca-4,9-diene t.&A-3-=.a-6-diol), respectively. Intramolecular [2+2] photocyclization of this tricyclic diol afforded the corresponding cage diol, 3-methyl-7phenylpentacyclo[5.4.0.0 2 ,6 .03 , 1 0 .05, 9 ]undecane-.exogxa-8,11-diol. Oxidation of this cage diol with pyridinium chlorochromate in dry dichloromethane afforded a single, isomerically pure cage hydroxyketone, 3-methyl-7 phenylpentacyclo[5.4.02,6.03,l .1519]undecane-xA-8-ol-II-one, whose structure was established by single crystal X-ray crystallographic methods.

The levels of total nicotinamide adenine dinucleotide (NAD) and nicotinamide adenine dinucleotide phosphate (NADP), and their redox states were determined as the function of growth in S. cerevisiae. Cells growing in a medium containing 0.8% glucose exhibit two phases of exponential growth, utilizing glucose and ethanol, respectively. The NAD pool is 50% reduced during both stages of growth while the NADP pool is 67% reduced in glucose growth and 48% reduced in ethanol growth. The NAD/NADP ratio is constant during growth on glucose and a two-fold increase in the NAD/NADP ratio occurs upon exhaustion of glucose. The increased ratio is maintained during growth on ethanol. This alteration in the regulation of the relative levels of NAD and NADP may be due to a change in the regulation of NAD kinase and/or NADP phosphatase activities. These changes may be related to the redox state of the NADP pool.

Evidence is reported for the formation of carbon-containing contamination products at the copper-tungsten (Cu-W) interface during the metal organic chemical vapor deposition (MOCVD) of copper on tungsten. Cu(II)bishexafluoroacetylacetonate [Cu(hfac)_2] was physisorbed onto lightly oxidized tungsten (WO_x) at 115K, under ultra-high vacuum conditions, and then annealed sequentially to higher temperatures. Copper reduction was observed by 320K. Carbonaceous and carbidic contamination of the WO_x surface was observed, even after sample warming to 625K in UHV. The results indicate that low temperature MOCVD of Cu may be possible, but interfacial contamination from the organic ligand fragmentation is a major concern.

Diels-Alder cycloaddition of methylcyclopentadienes to 2,5-dibromo-p-benzoquinone was performed. A single, isomerically pure cycloadduct was isolated, whose structure was assigned via analysis of its 1-D and 2-D NMR spectra. Diels-Alder cycloaddition of methylcyclopentadienes to 2 -methoxy-p-benzoquinone was performed. A single, isomerically pure cycloadduct was isolated, whose structure was assigned via analysis of the 1-D and 2-D NMR spectra of this cycloadduct and its reduction product obtained via stereo-specific reduction with sodium borohydride in the presence of cerous chloride. The structure of Thiele's ester was assigned via analysis of its 1-D and 2-D NMR spectra.

Web-based homework systems are becoming more common in general chemistry as instructors face ever-increasing enrollment. Yet providing meaningful feedback on assignments remains of the utmost importance. Chemistry instructors consider completion of homework integral to students' success in chemistry, yet only a few studies have compared the use of Web-based systems to the traditional paper-and-pencil homework within general chemistry. This study compares the traditional homework system to four different Web-based systems. Data from eight, semester classes consisting of a diagnostic pre-test, final semester grades, and the number of successful and unsuccessful students are analyzed. Statistically significant results suggest a chemistry instructor should carefully consider options when selecting a homework system.

This study expands the role of polythiophenes as an electron donating chromophore within energy harvesting milti-modular donor-acceptor systems. The polythiophene moiety would act as an electron donating spacer group between the donor and acceptor entities, viz., phenothiazine and fulleropyrrolidine, respectively, in the newly synthesized supramolecular triads. The triads 10-{[2,2';5',2"] terthiophene-5-fulleropyrrolidine} phenothiazine and 10-{[2,2'] bithiophene-5-fulleropyrrolidine} phenothiazine were synthesized and characterized through electrochemical and spectroscopic methods to ascertain their structural integrity. the componets of the triads were selected for their established redox parameters. Phenothiazine would act as a secondary donor and would facilitate hole-transfer from the polythiophene primary electron donor, due to its ease of oxidation and yield a long-lived charge separated state. Fulleropyrrolidine would act as an acceptor for ease of reductive capabilities and its ability to hold multiple charges. Finally, occurrence of photoinduced electron transferleading to the anticipated charge separated states is established from advanced transient spectroscopic techniques on these novel supramolecular systems.

Laser Ablation Inductively coupled plasma mass spectrometry (LA-ICP-MS) and Raman spectroscopy are both powerful imaging techniques. Their applications are numerous and extremely potential in the field of biology. In order to improve upon LA-ICP-MS an in-house built cold cell was developed and its effectiveness studied by imaging Brassica napus seeds. To further apply LA-ICP-MS and Raman imaging to the field of entomology a prong gilled mayfly (Ephemeroptera: Leptophlebiidae) from the Róbalo River, located on Navarino Island in Chile, was studied. Analysis of both samples showcased LA-ICP-MS and Raman spectroscopy as effective instruments for imaging trace elements and larger molecules in biological samples respectively.

Organometallic catalysis has attracted significant interest from both industry and academia due to its wide applications in organic synthetic transformations. Example of such transformations include the reaction of a zinc carbenoid with olefins to form cyclopropanes. The first project is a computational study using both density functional and correlated wavefunction methods of the reaction between ethylene and model zinc carbenoid, nitrenoid and oxenoid complexes (L-Zn-E-X, E = CH2, NH or O, L = X = I or Cl). It was shown that cyclopropanation of ethylene with IZnCH2I and aziridination of ethylene with IZnNHI proceed via a single-step mechanism with an asynchronous transition state. The reaction barrier for the aziridination with IZnNHI is lower than that of cyclopropanation. Changing the leaving group of IZnNHI from I to Cl, changes the mechanism of the aziridination reaction to a two-step pathway. The calculation results from the epoxidation with IZnOI and ClZnOCl oxenoids suggest a two-step mechanism for both oxenoids. Another important example of organometallic catalysis is the formation of alkyl arenes from arenes and olefins using transition metal catalysis (olefin hydroarylation). We studied with DFT methods the mechanism of a novel Rh catalyst (FlDAB)Rh(TFA)(η2–C2H4) [FlDAB = N,N’ -bis(pentafluorophenyl)-2,3-dimethyl-1,4-diaza-1,3-butadiene; TFA = trifluoroacetate] that converts …

Extended Hückel methods are known to be a useful tool in understanding surface phenomena. Important quantities about atoms and chemical bonds can be obtained from this computationally simple method, although caution must be exercised in interpreting the results. Application of Extended Hückel calculations to large metal clusters reveals the role of d orbitals in solids. Basic ideas of constructing model compounds have been developed. Several model systems for surface chemisorption processes are constructed in order to understand the surface catalyzed oxidative degradation of polyperfluoroethers. The activation of oxygen molecules can be explained. The Lewis acid character of the iron fluoride surface can be predicted. Based on these results, mechanisms of the degradation processes are discussed.

I. Reductive dimerization of pentacyclo[5.4.0.0.^2,6.0^3,10.0^5'9]undecane-8-one-(PCU-8-one, 53) affords a mixture of meso and d,l pinacols (55a and 55b respectively). Acid promoted rearrangement of 55a and 55b conceivably can proceed with migration of C(7)-C(8) and/or C(8)-C(9) to form the corresponding pinacolone(s). In our hands, acid promoted rearrangement of 55a and 55b each proceeds with exclusive migration of C(7)- C(8) bond, thereby affording 58a and 59a respectively. Mechanistic features of this rearrangement are discussed. II. 4,7,1 l-trimethylpentacyclo[6.3.0.0.^2,6.0^3,l0.0^5,9]undecane-exo-4,exo-7-diol (23a) was successfully synthesized. This diol crystallizes in a helical tubuland lattice although its molecular structure does not possess C2 rotational symmetry.

Detection of ultratrace levels of metallic ion impurities in hydrofluoric acid solutions and alkaline hydrogen peroxide solution was demonstrated using a silicon-based sensing electrode. The sensor's operation principle is based on direct measurements of the silicon open-circuit potential shift generated by the interaction between metallic ions and the silicon-based sensing surface. The new sensor can have practical applications in the on-line monitoring of microelectronic chemical processing. The detection of Ag+ content in KODAK waste water was carried out successfully by this novel sensor. Trace levels of organic impurities in the hydrofluoric acid solutions and in the cleanroom air were characterized by multiple internal reflection infrared spectroscopy (MIRIS) using an organics probe prepared directly from a regular silicon wafer.

A Series of fluorophores of the general formular P(CF2)nP and P(CF2)n-1CF3 has been synthesized. Copper catalyzed coupling of 1-bromopyrene and the corresponding mono and di-iodoperfluoroalkanes were used in most cases. For the n=3 dimer, a novel 1,w-perfluoroalkylation of pyrene via bis-decarboxylation of hexafluorogultaric acid was utilized. These compounds, along with suitable hydrocarbon analogs, are being used to study the flexibility of fluorocarbon chains using emission. We have found that the excimer formation for the fluorinated pyrene monomers is highly dependent on concentration and is less efficient than for pyene. Excimer formation for the fluorinated pyrene dimers is much more efficient than for the fluorocarbon monomers and is only slightly concentraion dependent. Steady-state emission spectra indicate hydrocarbon dimers-models form excimers more efficiently than the fluorinated dimers suggesting the fluorinated chains are stiffer than the hydrocarbons. We conducted the temperature-dependent studies and quantified the conformational difference.