Single-walled carbon nanotubes SWNTs) are a unique family of all carbon one dimensional nanomaterials that offer extraordinary mechanical, electrical and thermal properties leading to great promises in applications ranging from composite materials, nanoelectronics, electrochemical devices, biology to analytical science. This dissertation describes the synthesis and solution manipulation of single-walled carbon nanotubes and their applications in electrochemistry. Single-walled carbon nanotubes were synthesized by chemical vapor deposition method. SWNTs were individually and randomly grown on silicon substrates, which were used in study of the dielectric properties of SWNTs. As-produced SWNT bundles were individually dispersed in aqueous solution using designed “polysoap” surfactants. The polysoaps are synthesized by functionalizing the side chain of polystyrene-alt-maleic acid) with aminopyrene. The designed polysoaps adsorb on the sidewalls of SWNTs and exhibit dispersion efficiency better than DNA. In addition, SWNT-metal nanoparticle NP) assemblies were synthesized by using the polymer-SWNT complexes as templates for the binding of metal ions and metal NPs. Temperature and pH-responsive single-walled carbon nanotube dispersions were realized by using polyN-isopropylacrylamide) and poly- L-lysine solutions as dispersion surfactants. The dispersion or aggregation of SWNTs in water can be controlled by adjust the temperature or pH values of the solution. Transparent and conducting SWNT thin film were prepared and used as electrochemical electrodes for bioactive redox enzymes or photosystem II PSII) immobilization. The employment of SWNT thin films as electrodes alleviates the requirement for metal or glassy carbon supporting electrodes and direct electron transfer is observed on laccase-SWNT cathodes. The amperometric response to the visible light of PS II–SWNT film bioelectrode reveals the potential application in PS II based solar cells. Glucose oxidase GOx) was immobilized on glassy carbon electrode using poly-L-lysine PLL) and Nafion polymers. The Nafion-PLL-GOx modified electrodes display direct electron transfer DET) without the aid of any nanomaterials. The GOx in modified electrodes retains its biocatalytic activity and oxidizes glucose efficiently.

Located at a branching point in the methionine salvage pathway, acireductone dioxygenase ARD) represents an unusual case where two functional enzymes with different chemistries are derived from the same polypeptide chain. When Fe2＋ is bound in the active site, the enzyme catalyzes the on-pathway reaction that leads to methionine recovery. However, Ni 2＋-bound ARD, which targets the same substrate, leads to an off-pathway shunt. The active site characterization of these two isozymes in Klebsiella oxytoca is described in the first part of this thesis. This first part also deals with structural and mechanistic studies of bacterial E1 enolase-phosphatase, the bifunctional enzyme that catalyzes the formation of ARD substrate. Part II is directed toward the structural characterization of the human ARD homolog HsARD). Just like its bacterial counterpart, Fe2＋ in the active site leads to the on-pathway reaction, but Mn2＋-containing HsARD is the form responsible for the off-pathway reaction. The implications of Mn2＋ paramagnetism on NMR signals are discussed. For structural studies, HsARD expression in a bacterial system was improved by a factor of 4 in minimal growth medium supplied with isotopic labels and trace metals. Rapid loss of enzyme activity was successfully suppressed, although the issue of protein aggregation remains to be addressed. Part III of this thesis concerns structure-function studies of a bacterial P450 enzyme. Cytochrome P450s constitute a large superfamily of heme-thiolate proteins that catalyze a wide variety of reactions. Although they share similar structural folds, some P450s are highly substrate specific, while others are promiscuous. P450cam, or CYP101, from Pseudomonas putida catalyzes the 5-exo-hydroxylation of camphor and requires the presence of redox partner putidaredoxin Pdx). High-resolution solution NMR was used to investigate the effects of substrate replacement in CYP101 on regions that are remote from the active site. Finally, we used residual dipolar couplings along with molecular dynamics to generate a preliminary structure of Pdx-free CYP101 in solution.

Isocyanate, NCO, is known to form on platinum-group metals in the course of the catalytic reduction of NO by carbon-containing molecules, such as CO or simple hydrocarbons. The surface chemistry of isocyanate and its precursor, isocyanic acid, HNCO, have been presented in this thesis. This study was done under ultrahigh vacuum UHV) conditions on Pt111) with surface sensitive techniques. Exposure of the Pt111) surface at 90 K to HNCO leads to both molecularly adsorbed HNCO, as well as its dissociation products, H and NCO. The decomposition of HNCO is largely completed when the surface is heated to 150 K. As the temperature is increased from 150 to 300 K, a series of HNCO and NCO decomposition products are identified with RAIRS, including CO, NH, NH2, NH3, H2O, OH, and NO. These reaction products indicate that NCO dissociation can occur at both the N-C and C-O bonds. It has also been shown that the co-adsorption of oxygen and nitrogen atoms stabilize the HNCO species beyond 300 K, as compared with the disappearance of RAIRS peaks associated with HNCO on Pt111) &sim； 150-200 K) alone. Molecular oxygen co-adsorption stabilizes the NCO species beyond 300 K as well. Finally, the formation of NCO on the Pt111) surface has been attempted using a variety of adsorbates. Isocyanate was successfully produced from the reaction of acetylene-derived carbon with NO, albeit in small quantities.

Insulin secreting beta-cells are a very complicated biological system in which various cellular components coordinate many cellular processes and communication between different cell types. There is a long history of experimental and theoretical research which helped establish the current understanding of the system i.e. insulin secretion beta-cells) in great detail. What is absent from this rich literature is an understanding of how cooperativity of these various mechanisms affect the overall function of the system. How glucose plays a leading role in the tight control of the stimulatory and inhibitory factors in the beta cells remains to be completely understood. Additionally, it is rather difficult to predict how the system will behave in different physiological environments. In our research, we applied tools commonly used in chemistry, such as correlation function analysis and probability distribution functions to quantify the functions of the cells. We aim to better understand the molecular dynamics underlying insulin secretion in pancreatic beta-cells by quantifying the dynamics accurately using Segmented Spatio-Temporal Image Correlation Spectroscopy and additional quantitative tools originating from financial mathematics. These analytical tools resulted in a better understanding of the various transport dynamics that were hidden when analyzed with traditional analysis. We also designed chemical perturbation measurements to entrain or control the calcium oscillations in insulin secreting cells.

The spectroscopy and dynamics of various van der Waals complexes have been invesitgated. The electronic spectra resulting from the B&tilde； — X&tilde；) transitions in He&middot；&middot；&middot；Br 2 and He&middot；&middot；&middot；I2 were calculated and compared to each other and to experiment. Differences in the higher energy spectral feature in both the experimental and calculated spectra led to the question of the origin of its structure. To investigate this difference, the He&middot；&middot；&middot；Br 2 spectrum using the parameters from the He&middot；&middot；&middot；I 2 B&tilde；-state potential surface, and the He&middot；&middot；&middot；I 2 spectrum using the B&tilde；-state potential parameters of He&middot；&middot；&middot；Br2 were calculated. It was determined that the features within the spectra are dictated by the rotational structure of the I2/Br2 rather than the anisotropies in the potential surface. This theory was further tested by approximating the He&middot；&middot；&middot；I 2 B&tilde；-state surface as a simplified elliptical potential which further demonstrated that the spectral structure of these systems, initially believed to be very complex, can be described with simple models that are relatively insensitive to the details of the potential surface. Excited-state probability amplitudes and their corresponding energies have been calculated for the H2&middot；&middot；&middot；I2 and D2&middot；&middot；&middot；I2 systems to gain insights into the nature of the excited states. Due to the nature of the van der Waals bond between the H2/D2 and the I2 and the relative insensitivity of these rare gas-dihalogen complexes to the details of the excited-state surfaces, it was assumed that there is little dependence on the orientation of the H2/D2 axis relative to the I2, and the H2/D2 were treated as spherical. The calculations of the H2&middot；&middot；&middot；I 2 and D2&middot；&middot；&middot；I2 intermolecular vibrational energies within the H2/D2 ＋ I2 B, v＝20) potential energy surface PES), using a scaled potential model based on the He ＋ I2B, v＝20) were performed, and the resulting energies were compared to experiment to help in the assignment of spectral features. To investigate the dynamics of van der Waals species, hydrogen-transfer reactions were probed through vibrational excitation of the HCl bond in the pre-reactive F&middot；&middot；&middot；HCl complex. A three-dimensional, fully-coupled potential energy surface has been constructed based on electronic energies calculated at the multireference configuration interaction＋Davidson correction MRCI＋Q) level of theory with an aug-cc-pVnZ n ＝ 2； 3； 4) basis. Here the results of time-dependent quantum wave packet calculations where the reaction is initiated by vibrationally exciting the HCl stretching motion in the pre-reactive F&middot；&middot；&middot；HCl complex are presented. Product state distributions are calculated for reactions initiated in the first three vibrationally excited states of HCl, and results show that we see a promotion of the reaction for all three excitations with the probability of reaction increasing with increasing energy.

MRI has considerable potential as a non-destructive probe for visualizing and quantifying fluids in porous media. Its application in petro-physical analysis has not been fully developed. The major difficulty is that realistic porous media are challenging samples for traditional MRI methods due to their very short signal life times and large internal magnetic field gradients which arise from inhomogeneity in the microscopic magnetic susceptibility. Specialized MR imaging techniques are therefore required and the development and application of such techniques is the basis of this thesis. In this thesis, pure phase encoding imaging techniques, Single Point Ramped Imaging with T1 Enhancement SPRITE) and Spin Echo Single Point Imaging SE-SPI), have been further developed. Applications of these new imaging techniques include the following research areas. 1) Quantitative observation and evaluation of enhanced oil recovery EOR) in porous media. Three quantitative methodologies were employed to discriminate water/oil in porous media. Two of these strategies rely on different oil/water isotopic pairs for SPRITE MRI, such as fluorinated oil/water and hydrocarbon/D 2O. We also explore a general method to discriminate water and oil in rock via the molecular diffusion coefficient. All three methods were employed to evaluate EOR processes in porous media. 2) Single phase flow velocity measurement and visualization in porous media. We explored a general approach to facile and accurate flow and dispersion coefficient mapping of fluids in porous media. Compared with other MRI velocimetry methods, this new approach has proven to be very robust in characterizing fluid behavior and may be adapted to a wide range of flow systems. 3) Quantitative analysis of fluids in petroleum reservoir core plugs. The Spin Echo Single Point Imaging SE-SPI) technique was modified to permit fast determination of spatially resolved T2distributions in core analysis. Parameters of an empirical equation for NMR well logging data interpretation were determined by employing the SE-SPI imaging technique. Compared to traditional bulk calibration procedures, the proposed MRI calibration procedure is much simpler, faster and more robust. In general, the pure phase encoding imaging techniques developed and created in this thesis will permit valuable new applications in petro-physical analysis of porous media.

The supramolecular interactions of small organic molecules with different host molecules are investigated in this dissertation. Additionally, the author also describes the self-assembly mechanisms in hydrogen bonding motif. These studies were carried out by many techniques including, NMR, cyclic voltammetry, steady state voltammetry, mass spectroscopy, UV-visible spectroscopy and fluorescence spectroscopy. Chapter 1 introduces the science of supramolecular chemistry and the background of cucurbiturils, one of the most important host molecules studied in this research work. It describes the structures and binding behaviors of each host molecule. Additionally, the selectivity and binding properties in the host-guest interactions involved cucurbiturils are discussed. Chapter 2 compares the electrochemical properties of cationic and neutral ferrocene derivatives upon addition of cucurbiturils. It is observed that the cationic ferrocene compounds bind to cucurbit[7]uril much stronger compared to the neutral ferrocene compounds. The positive charged side chains favor to interact with cucurbit[7]uril portals and thus stabilize the complexes. Besides, the author describes a simple analytical method to determine the binding constants by a competitive binding with a standard reference compound, cobaltocenium, which is reported to bind strongly to cucurbit[7]uril. Chapter 3 described the research of the pH-dependent binding affinity between cucurbit[7]uril and ferrocene guests. The electrochemical behavior of ferrocene moiety in aqueous solution was investigated by cyclic voltammetry in the presence of cucurbit[7]uril in acidic and basic environment respectively. The protonation and deprotonation processes affect the binding behaviors of the ferrocene residues with cucurbit[7]uril. Chapter 4 describes the synthesis and characterization of a new series of 4-phenyl-pyridinium derivatives. These compounds contain a phenyl-pyridinium residue which is favorable to be bound by cucurbit[8]uril. The 1:1 and 1:2 host-guest binding stoichiometries are both observed by UV-visible spectroscopy. These new compounds can be dimerized encapsulated inside the cucurbit[8]uril portals without being electrochemical reduced. Chapter 5 is a brief introduction into the science of hydrogen bonding. This chapter investigates the application of multiple hydrogen-bonding in supramolecular chemistry extensively. Multiple hydrogen bonds with their directionality and reversibility are of great interest and importance in the design and investigations of well-defined supramolecular assemblies. The potential of hydrogen bonding is limitless and is still developing. Chapter 6 describes the synthesis and photochemical behaviors of a series of ureido-pyrimidione derivatives. All of the DDAA derivatives form stable, non-covalent dimers in non-polar solvents. The dimeric molecular assemblies of these hydrogen bonding motifs in their DDAA pyrimidinedione units are investigated by NMR, X-ray crystallography, fluorescence spectroscopy and computations. Additionally, their heterodimerization is well studied by fluorescence spectroscopy. The observation and comparison of fluorescence quenching on the photochemical fluorophore for each compound by ferrocene-DDAA and isopropyl-DDAA reveal the electron transfer process through the quadruple hydrogen bonding motifs.

High-energy light was generated from lower-energy photons through an upconversion process using a mixture of a photosensitizer and an emitter. Factors that influence efficiency of the process were studied. Several rutheniumII) complexes coordinated with bi- and polypyridyl ligands were prepared and used as photosensitizers. Anthracene and its derivatives were used as emitters. In each experiment, the upconversion sample was irradiated with a laser and the emission was monitored. The emission spectra exhibited upconversion 415-513 nm), scattering laser light 514 or 632.8 nm), and phosphorescence ＞550 nm). The laser beam was positioned close to the edge of the sample cuvette to avoid a reduction in the upconversion emission caused by self absorption. Increases in laser power, photosensitizer concentration, or emitter concentration increased the upconversion intensity Iu). Dissolved oxygen caused a minor decrease in Iu. Different photosensitizer and emitter derivatives were tested. Homoleptic ruthenium complexes were more effective photosensitizers with DPA as emitter than their heteroleptic analogues. Upconversion was detected in the [Rudeab) 3]PF6)2 deab ＝ 4,4-bisN,N-diethylamino)-2,2-bipyridine) and DPA system using helium-neon 632.8 nm) and argon ion 514 nm) lasers, indicating the same process can occur whenever the photosensitizer absorbs the incident radiation. A detailed mechanism is proposed in which an excitation photon is absorbed by a sensitizer to produce an excited triplet state. Energy is transferred from sensitizer to emitter by collision, generating triplet excited emitter. Two emitter triplets annihilate to produce one highly excited singlet. This singlet emits the upconversion photon. The steady-state approximation is used to explore the upconversion and phosphorescence Ip ) intensities. Ip has a first order dependence on laser power, while Iu varies between first and second order. The variable power dependence of I u occurs because of the competition between triplet-triplet annihilation and other decay pathways. Finally, Iu/Ip 2) is proportional to the second order of DPA concentration. These results generate a better understanding of the upconversion process and they will help to direct the work of others to enhance the efficiency of photonic devices. Practical applications of upconversion, such as the development of better photovoltaic cells, will be aided by the work described herein.

The synthesis and characterization of a series of novel hydrophobic room temperature ion liquids RTILs) are reported along with their applications in a variety of different systems ranging from electrochemical cells to biphasic separations. The effect of alkyl chain length, anion composition, and the SiO2 surface charge density were examined in 1-alkyl-3-methylimidazolium cations Cnmim, n ＝ 4, 6, 8, 10, 12) at the RTIL/SiO2 interface using sum frequency vibrational spectroscopy SFVS). These studies concluded that the orientation of the 1-alkyl-3-methylimidazolium cation was dictated largely by the length of the alkyl chain. As the alkyl chain length increased, the number of gauche defects in the chain decreased, and the imidazolium ring orientation becomes more perpendicular to the SiO2 surface. Changes in the surface charge density of the SiO2 also affected the orientation of the imidazolium ring. As the surface charge density became more negative the imidazolium ring oriented more parallel to the surface. Additionally, the oxidation of hydrogen and reduction of oxygen were examined in two hydrophobic RTILs. The RTILs used in this study were C 12mim bisperfluoroethylsulfonyl)imide BETI) and 1-dodecylimidazolium C12im) BETI. The water concentration in the system was examined in addition to effects due to cation composition. Under water-equilibrated conditions the C12imBETI was more efficient than C12mimBETI and exhibited greater thermal stability in the electrochemical cell. Under ambient conditions the performance of the C12imBETI decreased and the performance of the C12mimBETI increased. This contradictory trend was attributed to different water structures within the RTILs. Finally, the subclass of chiral RTILs was explored. The chiral RTILs were made by pairing the D or L-N-hexyl-alpha-methylbenzylammonium C6mba) and the D or L-N-hexyl-N,N,-dimethyl-alpha-methylbenzylammonium C611mba) cation with BMSI and BETI anions. The bulk properties of these RTILs were examined under both water-equilibrated and ambient conditions and were found to be independent of enantiomeric form. Their structure at an octadecyltrichlorosilane coated SiO2 surface was examined using counterpropagating second harmonic generation SHG). It was found that the most hydrophobic RTIL, C611mbaBETI, exhibited the highest adsorption at this interface. The studies presented here give new insight into how the ion composition of RTILs affects interfacial, bulk, and electrochemical properties.

The anion slow photoelectron velocity-map imaging SEVI) technique, a high resolution &sim；1 cm-1) variant of anion photoelectron spectroscopy, is applied to the study of open-shell anions and neutral species. First, SEVI is used to study the CnH n＝5-9), C2nN n＝1-3), CnO n＝2-3) and CnS n＝2-3) heteroatom doped carbon clusters. The SEVI spectra are assigned with the help of electronic structure calculations and Franck-Condon simulations. Precise electron affinities, term energies and vibrational frequencies are determined for these species. These studies also yield evidence of vibronic coupling in the ground states of C6H, C8H, C9H and CCS. Futhermore, it is found that the ground states of the C5H -, C7H-, C9H-, C4N- and C6N- anions are linear 3Sigma- states, contrary to previous theoretical studies that reported bent structures. In addition, the strong vibronic coupling between the very close-lying 2A1 and 2B2 states of the HCO 2 and DCO2 radicals is studied using SEVI. The complex photodetachment spectra are simulated and assigned using a quasidiabatic Hamiltonian approach. The strong vibronic coupling is highlighted by the observation of several nominally forbidden transitions. The SEVI technique is also applied to the study of the weakly bound ArO and KrO van der Waals complexes. The interaction potential and spin-orbit splitting of the neutral and anion states are determined and compared with high-level electronic structure calculations. Finally, the SEVI spectra of the ClH2- and ClD2- anions are used to characterized the electronic and nuclear coupling in the pre-reactive region of the Cl2P)＋H2 reaction and to understand the reactivity of the excited spin-orbit state of chlorine. The SEVI spectra are compared to simulations with and without non-adiabatic couplings between the Cl spin-orbit states. The non-adiabatic effects are found to be small but their inclusion improves agreement with experiment. The second part of this work concerns the structure of ionic clusters which is studied with infrared multiple photon dissociation IRMPD) spectroscopy. The stepwise solvation of the bicarbonate anion is probed by acquiring the IRPMD spectra of HCO3&macr；H2O)1-10 clusters in the gas-phase. Electronic structure calculations have been performed on the n＝1-8 clusters to identify the structure of the low-lying isomers and to assign the observed spectral features. It is found that the water molecules preferably bind to the negatively charged CO2 moiety of the HCO 3&macr； anion. A binding motif consisting of a four-membered ring with each water forming a single H-bond with the CO2 moiety is found for clusters with n＝4 or larger. In addition, the structure of the small SiO) 3-5＋ clusters have been studied with IRPMD and electronic structure calculations. The onset for the formation of the first Si-Si bond is observed for the n＝5 cluster.