Eskom has embarked on the development of the Pebble Bed Modular Reactor to generate electricity at low cost compared to that of coal with no greenhouse gas emissions. The proposed PBMR requires about 600 tons of nuclear-grade graphite blocks in its construction. A considerable amount of pitch is required as impregnants for the manufacture of this graphite. Anthracene oil is a high-boiling coal-tar distillate fraction consisting of a complex mixture of mainly unsubstituted polyaromatic hydrocarbons, with some methyl substitution. Conversion to pitch may be effected by dehydrogenation, i.e. volatile oil molecules condensing together to yield material of high molecular mass. Two dehydrogenation reagents, elemental sulfur and a novel reagent, hexachlorocyclohexane (HCH), an industrial waste product, were used to give three series of pitches with differing softening points. These products were characterised by standard pitch analyses, elemental analyses, thermogravimetric analysis (TGA), proton nuclear magnetic resonance spectroscopy (1HNMR), gas chromatography (GC), gas chromatography–mass spectrometry (GC-MS), Maldi-TOF mass and mass probe spectrometry and then compared with commercial pitch grades from Mittal Coke and Chemicals. The results obtained showed that the reaction products reacted with 15 and 20 wt % of sulfur, with the softening points of 61.3 and 91.4 °C, would be suitable as commercial products. All pitches showed very little, if any, ash, making them suitable for use in the manufacture of high-purity graphite. Pitches prepared with 15-20 wt % of sulfur and HCH pitches may have more applications in impregnation because of their low QI content. Total sulfur content detected by elemental analysis is high. This is undesirable because sulfur may cause puffing which will result in poor quality of graphite. All pitches show very little, if any, ash, making them suitable for use in the manufacture of high-purity graphite. TGA results showed that pitches prepared with higher concentrations of sulfur can be suitably used as impregnants because of their high coking yields. The coking yields of HCH-derived pitches are lower than those of Mittal Coke and Chemicals commercial pitches. Results from the (1HNMR showed that cross-linking on reaction with sulfur is through aliphatic carbon atoms; the percentages of aliphatic protons decrease with the increase in the sulfur concentration, and aromatic percentages increase. There is a slight increase in the proportion of aromatic protons of the HCH pitches; therefore cross linking is through aromatic-aromatic carbon atoms. Model reactions were prepared by reacting pure aromatic hydrocarbons with HCH, demonstrating the incorporation of the dehydrogenation reagent. These reactions were used to determine the reactivity of the main components of anthracene oil. The reaction products were characterised by Maldi-TOF and GC-MS. The results obtained from HCH pitches showed the formation of chlorobenzenes. This is undesirable because chlorine may cause corrosion of the equipment during coking. / Dissertation (MSc (Chemistry))--University of Pretoria, 2008. / Chemistry / unrestricted

Six polyamine anthracene conjugates (Ants) were studied that take advantage of the polyamine transporter system (PTS) to target specific cancer. The structural features of the Ants involve planar aromatic anthracene that has highly cytotoxicity properties and a polyamine chain similar to natural polyamine, which is taken up by eukaryote cells expressing the PTS actively. Experimental data show that Ants with di-substituted polyamine chains have significantly higher DNA binding affinities than the mono-substituted anthracene conjugates. The high ionic conditions (~150 mM NaCl and 260 mM KCl) in the eukaryote cell nucleus extensively impair the apparent DNA binding of the Ants, but may further reinforce DNA structural stability. Combining the published cytotoxicity of the PTS data with the DNA interaction data reported here, the di-substituted polyamine anthracene conjugates have the highest potential to, after cellular uptake via PTS, bind to DNA.

The research project aimed to synthesise semiconducting polymer brushes (polymer chains densely grafted to a surface) utilising simple and efficient organic chemistry methods, with a view to use in molecular-level electronic applications. Conjugated polymers were initially chosen for their ability to conduct electrical charge along a polymer chain by facilitating electron transfer between π-bonds. Polymers also aimed to be living , which could allow for further chain growth at a later point in time. This could lead to the production of various useful brush block co-polymers, with different blocks (or layers) of polymers having different chemical, structural and electronic properties. Initially, several syntheses towards monomers for poly(phenyl isocyanide) and poly(quinoxaline-2,3-diyl) were undertaken with limited success. Attention was turned to the synthesis of poly(thiophene)s by Kumada catalyst-transfer polymerisation (KCTP), again with varying success. After this, ring-opening metathesis polymerisation (ROMP) was explored as a possible avenue. The successful synthesis of several cyclopropenes for use as monomers was carried out. However, the ROMP of these monomers failed. ROMP of unsubstituted norbornene was successful. XPS studies suggested that vapour deposition of SAMs (Self Assembled Monolayers) gave homogenous monolayers. Solution-phase depositions appeared prone to inhomogeneous multilayer deposition. Vapour deposited SAMs gave better grafting densities at lower deposition pressures, leading to thicker polymer brushes. Finally, atom transfer radical polymerisation (ATRP) methods have been investigated. ARGET-ATRP was determined as the favoured method as it uses lower quantities of copper. Functionalised monomers for ATRP were synthesised, but homopolymers of these polyaromatic monomers have been difficult to synthesise by both copper-mediated ATRP and AIBN initiation. Polymer brushes and polymer brush diblocks of post-polymerisation modified PHEMA and PDMAEMA have been successfully grown on silicon wafers and glass slides, with a view to using the diblocks of these polymers as effective bulk heterojunction photovoltaic devices. The kinetics of the growth of both polymers by the ARGET and ATRP methods were studied to determine the degree to which each polymerisation is living; to determine if diblock growth would be possible. PHEMA brushes were successfully modified with a range of polyaromatic acid chlorides. Focussing on anthracene (which has excellent fluorescence properties, displaying a clear ability to move electrons between energy levels), this attachment was further confirmed by a range of techniques, before successfully growing a brush diblock of the unfunctionalised and functionalised polymers.

by Michael Tsang Ming Choi. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1999. / Includes bibliographical references (leaves 85-90). / Abstracts in English and Chinese. / ACKNOWLEDGMENT --- p.i / TABLE OF CONTENTS --- p.ii / LIST OF FIGURES --- p.iv / LIST OF TABLES --- p.vi / ABBREVIATIONS --- p.vii / ABSTRACT --- p.viii / 摘要 --- p.ix / Chapter PART I. --- "SYNTHESIS, SPECTROSCOPIC PROPERTIES AND AGGREGATION BEHAVIOR OF SUBSTITUTED 2,3- NAPHTHALOCYANINES" / Chapter 1 --- INTRODUCTION --- p.2 / Chapter 1.1 --- "Synthesis of 2,3 -Naphthalocyanines" --- p.6 / Chapter 1.2 --- Aggregation Phenomena of Phthalocyanines --- p.14 / Chapter 1.3 --- Phthalocyanines with Crown Ether Voids --- p.20 / Chapter 2 --- RESULTS AND DISCUSSION --- p.26 / Chapter 2.1 --- "Synthesis of Substituted 2,3-Naphthalocyanines" --- p.26 / Chapter 2.2 --- Synthesis of Substituted Phthalocyanines --- p.29 / Chapter 2.3 --- "Characterization of 2,3-Naphthalocyanines and Phthalocyanines" --- p.31 / Chapter 2.4 --- "Aggregation Behavior of Octasubstituted 2,3-Naphthalocyanines and Phthalocyanines" --- p.34 / Chapter 2.5 --- Liquid Crystalline Properties of64 --- p.43 / Chapter 2.6 --- "Synthesis of a Crown Ether-Substituted 2,3-Naphthalocyanine" --- p.45 / Chapter 2.7 --- Conclusion --- p.48 / Chapter 3 --- EXPERIMENTAL SECTION --- p.49 / Chapter 3.1 --- Materials --- p.49 / Chapter 3.2 --- Physical Measurements --- p.49 / Chapter 3.3 --- General Procedure for the Preparation of Dinitriles --- p.50 / Chapter 3.4 --- General Procedure for the Cyclization of Dinitriles --- p.53 / Chapter PART II. --- SYNTHETIC STUDIES OF SUBSTITUTED DICYANO-ANTHRACENES AND TETRACENES / Chapter 1 --- INTRODUCTION --- p.57 / Chapter 2 --- RESULTS AND DISCUSSION --- p.63 / Chapter 2.1 --- Synthesis of Substituted Anthracenes --- p.63 / Chapter 2.2 --- Synthesis of Substituted Tetracenes --- p.72 / Chapter 2.3 --- Conclusion --- p.77 / Chapter 3 --- EXPERIMENTAL SECTION --- p.78 / REFERENCES --- p.85 / Chapter APPENDIX --- Crystallographic data of dimer of anthracene118 --- p.91

Thesis (Ph. D.)--University of Texas at Austin, 2000. / Vita. Includes bibliographical references (leaves 182-193). Available also in a digital version from Dissertation Abstracts.

No description available.

Organic photovoltaics (OPVs) are mainly based on organic semiconducting small molecules, macromolecules, and polymers, which form an active layer in photovoltaics. They act as an active material in absorbing light and causing charge mobility to generate electricity from sunlight. This thesis describes the molecular systems derived from fused arenes such as anthracene, pyrene, carbazole and thiophene for use as either a donor or an acceptor component of the active layer of OPVs. Two novel molecular systems (9- anthracenecarboxy-1-methylpyrene, (1) and Py-bi-TH-ANT, (2) were prepared using Steglich esterification and Grignard metathesis followed by Kumada coupling. The molecular structure of each was confirmed by 1H-NMR and IR analysis respectively. The photophysical properties of the products were also evaluated in solution. The potential applicability of these two novel systems for OPVs will be studied in the future.

From introduction: The Fluorescence Excitation Spectrum or anthracene is known to vary considerably with the age and condition or the crystal. This thesis represents an attempt to improve the understanding of these variations. To put the problem on a quantitative basis it was found necessary to know both the ultraviolet reflection and absorption spectra. Reports of the reflection spectrum appear to have been confined to the case of polarised incident light. In addition the reflectivity measurements are always reported for a freshly cleaved surface. For these reasons the reflectivity of anthracene for various conditions of the reflecting surface was measured with unpolarised light. These varying reflectivities were used to further knowledge of the chemical processes at the crystal surface, as well as being used directly in the calculation of fluorescence excitation spectra. Reflection spectra with a- and b- crystallographic axis polarisations were also obtained. Since such spectra are reported in the literature it was possible, by comparison, to conclude that the experimental methods used in this thesis yielded valid results. The polarised measurements were used to obtain optical constants for the crystal. In the interests of readability most of the complicated process of converting the reflectivities to optical constants is dealt with in three appendices to the thesis.

No description available.

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 ruthenium(II) 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 [Ru(deab)3](PF6)2 (deab = 4,4'-bis(N,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 Iu occurs because of the competition between triplet-triplet annihilation and other decay pathways. Finally, (Iu/Ip2) 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.