Carbon-13 and proton nuclear magnetic resonance analysis of shale-derived refinery products and jet fuels and of experimental referee broadened-specification jet fuels

A proton and carbon-13 nuclear magnetic resonance (NMR) study was conducted of Ashland shale oil refinery products, experimental referee broadened-specification jet fuels, and of related isoprenoid model compounds. Supercritical fluid chromatography techniques using carbon dioxide were developed on a preparative scale, so that samples could be quantitatively separated into saturates and aromatic fractions for study by NMR. An optimized average parameter treatment was developed, and the NMR results were analyzed in terms of the resulting average parameters; formulation of model mixtures was demonstrated. Application of novel spectroscopic techniques to fuel samples was investigated

The Sorption of Sulfamethoxazole by Aliphatic and Aromatic Carbons from Lignocellulose Pyrolysis

Massive biomass waste with lignocellulose components can be used to produce biochar for environmental remediation. However, the impact of lignocellulose pyrolysis on biochar structure in relation to the sorption mechanism of ionizable antibiotics is still poorly understood. In this paper, diverse techniques including thermogravimetric analysis and 13C nuclear magnetic resonance were applied to investigate the properties of biochars as affected by the pyrolysis of cellulose and lignin in feedstock. Cellulose-derived biochars possessed more abundant groups than lignin-derived biochars, suggesting the greater preservation of group for cellulose during the carbonization. Higher sorption of sulfamethoxazole (SMX) was also observed by cellulose-derived biochars owing to hydrogen bond interaction. Sorption affinity gradually declined with the conversion aliphatic to aromatic carbon, whereas the enhanced specific surface area (SSA) subsequently promoted SMX sorption as evidenced by increased SSA-N2 and SSA-CO2 from 350 to 450 °C. The decreased Kd/SSA-N2 values with increasing pH values implied a distinct reduction in sorption per unit area, which could be attributed to enhanced electrostatic repulsion. This work elucidated the role of carbon phases from thermal conversion of lignocellulose on the sorption performance for sulfonamide antibiotics, which will be helpful to the structural design of carbonaceous adsorbents for the removal of ionizable antibiotics

Stream hydrological fragmentation drives bacterioplankton community composition

In Mediterranean intermittent streams, the hydrological fragmentation in summer and the successive water flow reconvergence in autumn allow exploring how local processes shape the microbial community within the same habitat. The objectives of this study were to determine how bacterial community composition responded to hydrological fragmentation in summer, and to evaluate whether the seasonal shifts in community composition predominate over the effects of episodic habitat fragmentation. The bacterial community was assessed along the intermittent stream Fuirosos (Spain), at different levels of phylogenetic resolution by in situ hybridization, fingerprinting, and 16S rRNA gene sequencing. The hydrological fragmentation of the stream network strongly altered the biogeochemical conditions with the depletion of oxidized solutes and caused changes in dissolved organic carbon characteristics. In the isolated ponds, beta-Proteobacteria and Actinobacteria increased their abundance with a gradual reduction of the alpha-diversity as pond isolation time increased. Moreover, fingerprinting analysis clearly showed a shift in community composition between summer and autumn. In the context of a seasonal shift, the temporary stream fragmentation simultaneously reduced the microbial dispersion and affected local environmental conditions (shift in redox regime and quality of the dissolved organic matter) tightly shaping the bacterioplankton community composition

Computational study of Aromaticity in Porphyrinoid Systems and Photosensitizers from Chemical Bonding Descriptors

291 p.La presente tesis está dividida en dos bloques. El primer bloque se centra en una de las propiedadesafectadas por el error de deslocalización, la aromaticidad, presente en algunas aproximaciones delfuncional de la densidad. Se estudia el carácter aromático de sistemas una familia de porfirínas simples,una serie de anulenos y un anillo de seis porfirínas. También se discute el método computacionalapropiado para caracterizar la estructura electrónica de moléculas aromáticas medianas y grandes.Siguiendo la misma línea, en el segundo bloque de la tesis se han examinado diferentes familias defotosensibilizadores y catalizadores para diseñar un protocolo riguroso para el estudio de la estructuraelectrónica, la simulación de espectros UV-Vis y para el cálculo de potenciales redox. Losfotosensibilizadores son moléculas captadoras de luz que presentan excitaciones de transferencia decarga. La simulación de estas excitaciones está afectada también por las deficiencias de lasaproximaciones al funcional de la densidad

Synthesis and chemistry of highly distorted polycyclic aromatic hydrocarbons

A significant feature of smaller cyclophanes and buckminsterfullerenes is the presence of nonplanar aromatic rings. Such compounds are of considerable interest due to both the synthetic challenge they pose and to their unusual conformational, spectroscopic, and chemical behavior. A great deal of work has focussed on determining the extent to which an aromatic ring can be distorted from planarity while remaining isolable under ambient conditions. Although this question has been examined in detail for isolated benzene rings (for example, through investigations of [n]paracyclophanes), analogous studies of polycyclic aromatic hydrocarbon (PAH) frameworks have never been pursued. -- Here the first systematic examination of the distortion from planarity of a PAH moiety is reported. The synthesis of a number of [n](2,7)pyrenophanes from [3.3]dithiacyclophane precursors is described. Some physical, spectroscopic, and chemical properties of these molecules are also described, and a number of X-ray structures of markedly nonplanar aromatic moieties are reported. From this data, it is concluded that the end-to-end bend of the most strained pyrenophane prepared is greater than the average end-to-end bend of the pyrene moiety. However, POAV analysis of the pyramidalization of pyrenophane sp² carbon atoms reveals markedly lower pyramidalizations than are observed in D₅h C₇₀. Attempts at the functionalization of [n](2,7)pyrenophanes in the hope of using them as precursors for larger nonplanar PAHs were made. However, suitable conditions for functionalization of pyrenophanes were not found. A synthetic approach to a C₂-chiral 1,6-[n]pyrenophane is also described. -- An attempted synthesis of a derivative of the buckybowl pinakene using a tandem Bergman cycloaromatization/free radical conjugate addition is presented. -- The experimental work is preceded by reviews of the literature concerning the concept of aromaticity, nonplanar aromatic molecules (especially [n]paracyclophanes) and fullerene fragments

Biochar Carbon stability in some contrasting soils from Australia

Climate change is one of the biggest challenges facing the world. The largest contributor to climate change is the greenhouse gas CO2, which is released through anthropogenic activities such as burning of fossil fuel and agricultural waste. To find solutions to mitigate climate change, research has been proposed to reduce greenhouse gas emissions or off-setting emissions through carbon (C) sequestration in soil − the largest C pool of terrestrial ecosystems. In this context, long-term C storage through biochar application to agricultural soils has been becoming a priority area of research in the last two decades

Biochar Carbon stability in some contrasting soils from Australia

Climate change is one of the biggest challenges facing the world. The largest contributor to climate change is the greenhouse gas CO2, which is released through anthropogenic activities such as burning of fossil fuel and agricultural waste. To find solutions to mitigate climate change, research has been proposed to reduce greenhouse gas emissions or off-setting emissions through carbon (C) sequestration in soil − the largest C pool of terrestrial ecosystems. In this context, long-term C storage through biochar application to agricultural soils has been becoming a priority area of research in the last two decades

Electron-rich Alkynes and Azodicarboxylates Chemistry Towards Vicinal Diamine Motif Containing Small Molecules and N-Heterocycles

Heterocyclic molecules that contain nitrogens and consist of four, five and six-membered rings such as azetidinones (eg: β-lactams), pyrroles, indoles, azoles, triazoles, oxadiazines, and oxadiazinones, etc. are ubiquitous in the use of pharmaceutical fields. This also reflected in the recently FDA approved unique small-molecule pharmaceuticals, where about 90% of those molecules contain a nitrogen heterocycle. Particularly, the vicinal diamino motif has been appeared in leading drug directing candidates such as penicillin, cephalosporins, and oseltamivir (Tamiflu) over the past years. Historically, there has been minimal interest in synthesizing a broad scope of vicinal diamino motif-containing small molecules and heterocyclic compounds for the purpose of using them in the medicinal fields. Therefore, synthesizing the vicinal diamino motif in a few synthetic steps with a broad substrate scope has remained challenging. In this work, we assess the potential to access the vicinal diamino skeleton through the reactivity of various azodicarboxylates (as the main nitrogen source) with various electron-rich alkynes. With further investigations, this chemistry leads us to develop novel methods to generate several classes of vicinal diamino motif-containing products, such as diazacyclobutenes (four-membered heterocyclic compound) and 2-iminothioimidates (acyclic vicinal diimino compounds), and highly substituted tetrahydroindoles (fused bicyclic compound consist of a five-membered N-heterocycle) in good yields with a broad substrate scope. Additionally, with the divergent reactivity of this chemistry under the catalytic environment; a novel compound consist of a 6-membered 1,3,4-oxadiazin-2-one heterocyclic skeleton was produced. This dissertation further discloses the substrate dependent reactivity, divergent reactivity, mechanistic investigations and variable temperature dynamic NMR studies of these novel compounds. In overall, this electron-rich alkynes and azodicarboxylates chemistry described in this document has been validated a novel protocol to rapidly access diverse vicinal diamino motif containing acyclic and cyclic compounds which have potential utility in organic synthesis and medicinal chemistry. Last part of this dissertation describes the development of a protocol for the in-house synthesis of the cellulose nanocrystals, optimization and scale up synthesis of the poly(etheleneimne) functionalized cellulose nanocrystals to investigate the possibility of reducing the cost of the synthesis while maintaining the environmental remediation properties of these functionalized materials at the same efficiency