ItemHeterobimetallic N‑Heterocyclic Carbene Complexes: A Synthetic, Spectroscopic, and Theoretical Study(2016-07-18) Pell, Thomas P.
A new synthetic methodology has been developed for the preparation of heterobimetallic group 11 and group 12 complexes of a symmetrical bis-NHC “pincer” ligand. The synthetic route involved the initial preparation of a mononuclear [Au(NHC)2]+ complex with pendent imidazole moieties on the NHC ligands. Subsequent alkylation of the imidazole groups with Et3OBF4 and metalation with a second metal ion (Ag(I) or Hg(II)) provided two heterobimetallic complexes. Four homobimetallic (Cu(I)2, Ag(I)2, Au(I)2, and Hg(II)2) complexes of the same bis-NHC “pincer” ligand were also prepared. The homobimetallic Cu(I)2, Au(I)2, and Hg(II)2 complexes and heterobimetallic Au(I)−Ag(I) and Au(I)−Hg(II) complexes and the synthetic intermediates for the heterobimetallic complexes were characterized by X-ray crystallography. These X-ray structures show that the bimetallic complexes adopt “twisted” conformations in the solid state, supporting short M···M interactions. Crystalline samples of the homobimetallic Ag(I)2 and Au(I)2 and heterobimetallic Au(I)−Ag(I) and Au(I)−Hg(II) complexes were emissive at room temperature and at 77 K. The geometries of the synthesized complexes were optimized at the M06-L/def2-SVP level of theory, and the electronic nature of the M···M interactions for all synthesized complexes was investigated using natural bond orbital (NBO) calculations.
ItemReactions of [PhI(pyridine)2]2+ with Model Pd and Pt II/IV Redox Couples(2014-02-03) Corbo, Robert
The results of the reactions of the dicationic iodine(III) family of oxidants [PhI(pyridine)2]2+ with model Pd(II) and Pt(II) complexes are described. Depending on the specific reaction pairs, a variety of outcomes are observed. For palladium, Pd(IV) complexes cannot be observed but are implicated in C−C and C−N bond formation for Pd(II) starting materials based on phenylpyridine and 2,2-bipyridine, respectively. Theoretical comparisons with similar processes for −Cl and −OAc rather than pyridine indicate that these provide greater thermodynamic stability, and our results here show that they also give greater kinetic stability (the failure of MP2 methods for these systems is quite dramatic). In contrast, oxidation and delivery of the pyridine ligands gives dicationic Pt(IV) complexes that may be isolated and structurally characterized.
ItemIridium Complexes of N-Heterocyclic Carbene Ligands: Investigation into the Energetic Requirements for Efficient Electrogenerated Chemiluminescence(2014-09-22) Stringer, Bradley D.
A series of five heteroleptic Ir(III) complexes of the general form Ir(ppy)2(C∧C:) have been prepared (C∧C represents a bidentate cyclometalated phenyl-substituted imidazolylidene ligand). The five complexes arise from the cyclometalated phenyl ring of the NHC ligand being unsubstituted or having electron-donating (OMe and Me) or electron-withdrawing (Cl and F) groups at the 2- and 4- positions of the ring. The synthesized phenyl-substituted imidazole precursors, imidazolium salts, and Ir(III) complexes have been characterized by elemental analysis, NMR spectroscopy, cyclic voltammetry, and electronic absorption and emission spectroscopy. The molecular structures for two imidazolium salts and two Ir(III) complexes were determined by single-crystal X-ray diffraction. Each of the Ir(III) complexes exhibited intense photoluminescence in acetonitrile solution at
room temperature with quantum yields (ϕp) ranging from 42% to 68% and excited-state lifetimes on the order of 2 μs. Voltammetric experiments revealed one formal metal-based oxidation process and two ligand-based reductions for each complex.
All complexes gave moderate to intense annihilation electrochemiluminescence (ECL); however, only the fluorinated complex produced significant coreactant ECL. The combined electrochemical, spectroscopic, and theoretical investigations offer insights into the reasons for this behavior and suggest useful strategies for the design of ECL emitters. A plot of oxidation potential versus emission color is proposed as a convenient reference guide to aid in the prediction of energy sufficiency in ECL reactions.
ItemActivation of the C–N Bond of N-heterocyclic Carbenes by Inorganic Elements(2014-09-14) Iversen, Kalon J.
N-heterocyclic carbenes (NHCs) are generally considered to be extremely robust, ideal spectator ligands. However, in the past two years there have been several reports of the activation of the endocyclic C–N bond with subsequent insertion into element–hydrogen and element–carbon bonds. The new reaction pathway casts the reactivity of the NHC heterocyclic ring into a new light, especially in the context of potential catalyst decomposition. The synthetic reports and theoretical studies in this rapidly developing area are summarized here.
ItemThe Dalton Quantum Chemistry Program System(2014-05-01) Aidas, Kestutis
Dalton is a powerful general‐purpose program system for the study of molecular electronic structure at the Hartree–Fock, Kohn–Sham, multiconfigurational self‐consistent‐field, Møller–Plesset, configuration‐interaction, and coupled‐cluster levels of theory. Apart from the total energy, a wide variety of molecular properties may be calculated using these electronic‐structure models. Molecular gradients and Hessians are available for geometry optimizations, molecular dynamics, and vibrational studies, whereas magnetic resonance and optical activity can be studied in a gauge‐origin‐invariant manner. Frequency‐dependent molecular properties can be calculated using linear, quadratic, and cubic response theory. A large number of singlet and triplet perturbation operators are available for the study of one‐, two‐, and three‐photon processes. Environmental effects may be included using various dielectric‐medium and quantum‐mechanics/molecular‐mechanics models. Large molecules may be studied using linear‐scaling and massively parallel algorithms. Dalton is distributed at no cost from http://www.daltonprogram.org for a number of UNIX platforms.
ItemIs the Perfluorinated Trityl Cation Worth a Revisit? A Theoretical Study on the Lewis Acidities and Stabilities of Highly Halogenated Trityl Derivatives(2014-06-10) Couchman, Shannon A.
The relative Lewis acidities of a series of known, unknown and observed but unstable halogenated derivatives of the trityl cation have been probed in a computational study. The Lewis acidity was investigated from hydride, fluoride and methide affinities. The results indicate that the perhalogen-ated trityl cation [C(C6F5)3]+ is a desirable synthetic target, especially in the modern age of weakly coordinating anions. Our results also indicate that the stable [C(C6Cl5)3]+ cation may be an equally interesting Lewis acid.
ItemSynthesis and Biological Evaluation of Substituted 3-anilino-quinolin-2(1H)-ones as PDK1 Inhibitors(2014-07-15) O'Brien, Nathan J.
PDK1 is an important regulator of the PI3K/Akt pathway, which has been found frequently activated in a large number of human cancers. Herein we described the preparation of novel substituted 3-anilino-quinolin-2(1H)-ones as PDK1 inhibitors. The synthesis is based around a Buchwald–Hartwig cross-coupling of various 3-bromo-6-substituted-quinolin-2(1H)-ones with three different functionalised anilines. The modular nature of the designed synthesis allowed access to a series of novel inhibitors through derivatisation of a late-stage intermediate. All compounds were screened against isolated PDK1 enzyme, with modest inhibition observed.
ItemThe First Bismuth–NHC Complexes(2014-01-14) Aprile, Antonio
The synthesis, isolation and crystallographic characterization of the first N-heterocyclic carbene adducts of bismuth is reported, by direct reaction of the Dipp2NHC (Dipp = 2,6-diisopropylphenyl) or iPr2(Me2)- NHC with BiCl3. This represents the last non-radioactive element from groups 13–17 for which an NHC– element fragment remained unreported.
ItemSynthesis and Biological Evaluation of Substituted 2-anilino-7H-pyrrolopyrimidines as PDK1 Inhibitors(2014-05-21) O'Brien, Nathan J.
An efficient and scalable route for a series of novel substituted 2-anilino-7H-pyrrolopyrimidine compounds as potential inhibitors of PDK1, an important regulator of the PI3K/Akt pathway that is dysregulated in many cancers, was developed and is described. The synthetic strategy was designed around Suzuki and BuchwaldeHartwig cross-couplings of a boronate fragment and various customised anilines sequentially with 2,4-dichloro-7-tosyl-7H-pyrrolopyrimidine. All fragments were constructed separately and cross-coupled to provide access to a range of novel compounds. Biological evaluation of these was undertaken, with modest inhibition observed.
ItemSynthesis of Substituted 4-(1H-indol-6-yl)-1H-indazoles as Potential PDK1 Inhibitors(2014-01-14) Brzozowski, Martin
The development of a preparative route to a series of novel 4-(1H-indol-6-yl)-1H-indazole compounds as potential PDK1 inhibitors is described. The synthetic strategy centres on the late-stage Suzuki crosscoupling of N-unprotected indazole and indole fragments. The use of a monoligated palladium catalyst system was found to be highly beneficial in the cross-coupling reaction. The indazole and indole fragments were constructed by diazotisation/cyclisation and SNAr/reductive cyclisation sequences, respectively.
ItemWhat Are Classrooms Like When Children Are Sorted By Ability: Australian Mathematics Classrooms(2009-10-01) Kilgour, Peter W.
Teachers all over the world are teaching Mathematics in classrooms that may have students grouped by ability. Often the decision to group or not to group is made arbitrarily or because this is the way classes have always been arranged. This book will provide a valuable insight into the impact ability grouping has on the learning environments of Mathematics classrooms. The reader will gain insights into how different stakeholders in the schooling process relate to the concept of academic segregation. Information will be revealed on students? preferred learning environment and the way their attitude to mathematics can be shaped by the way their classes are grouped. Principals, heads of departments, teachers at all levels and academics who are interested in the study of learning environments may be caused to think about and even reconsider their position on the place of ability grouping in the education process.
ItemA Study of the Christian Public's Engagement with the New Geology of the 19th Century and its Implications for the Succeeding Centuries(2014-12-01) Bootsman, Cornelis Siebe
While Christian communities had no problem engaging positively with the sciences of astronomy, physics and chemistry, they had difficulty engaging with the emerging geology and biology of the 19th century. The ancient earth and evolutionary models of geology and biology respectively were seen as a direct attack on the biblical Genesis model of a young earth and a creation that took place over the period of a week. Some Christian apologists used Baconianism and the Scottish Common Sense philosophy to suggest that geology was not a real science. Geology was characterised as consisting of wild speculation, hypotheses and theories and lacking in solid factual evidence. In both Britain and North America Christian respondents to the new geology were classified as harmonizing geologists or scriptural geologists. This paper considers the nature of these respondents, their philosophical positions, and how these positions took form in the succeeding centuries in terms of different cognitive geological styles. The implications for the science education and science in society context will be discussed.
ItemIntraocular Sparganosis (Platyhelminthes: Cestoda: Pseudophyllidea: Diphyllobothriidae) in the Green Tree Snake Dendrelaphis Punctulatus (Serpentes: Colubridae: Colubrinae).(2014-08-01) Annable, Terence J.
Sparganosis is a parasitic condition found almost on a worldwide scale that can infest fish, amphibians, reptiles, birds and mammals. In the case described a green tree snake was found to have a dormant intraocular parasite (sparganum) leading to glaucoma and blindness. The first intermediate host is a small aquatic crustacean, commonly Cyclops. Animals can become second intermediate hosts when they ingest contaminated water. The parasite encysts as a sparganum usually forming a small lump under the skin that may remain dormant for many years. The definitive hosts for these parasitic tapeworms are carnivorous mammals such as cats, dogs or even humans. The lifecycle is completed when this predator is eaten by a mammalian host. Understanding the lifecycle means hygienic action can be taken to reduce chances of infestation.
ItemThe Valley of a Thousand Plants: An Inventory of the Native Flora of the Catchment of Dora Creek, New South Wales(2014-01-01) Annable, Terence J.
This book has two main objectives in the eyes of the authors: To provide coordinated information about several components of the natural environment, including its biota as well as a record of the composition of the flora of the catchment of Dora Creek in the early 21st century.
ItemCoal Seam Gas Extraction: Does Landholder Compensation Match the Mischief?(2013-01-01) Fibbens, Michael
Coal seam gas (CSG) extraction is set for expansion in New South Wales. However, controversy accompanies its introduction in that the present law grants miners access to private lands for the purposes of exploration and production. The NSW Petroleum (Onshore) Act 1991 regulates compensation for land access, and a number of questions have been raised about the adequacy of its compensation provisions. Additionally, compensation for coal seam gas poses a challenge for the valuation profession in that valuation theory has yet to be developed in this emerging sphere of practice. This paper compares the legal and physical impacts of coal seam gas infrastructure on private lands with the current provisions of the NSW Petroleum (Onshore) Act 1991 and questions if the present compensation provisions match the injury inflicted upon the holders of private land by coal seam gas occupation. The paper reviews the NSW legislation and case law relating to coal seam gas acquisition to identify the legal affects, whilst field observation and remote sensing techniques identify physical effects. The physical effects are then categorised according to the heads of compensation that apply to the compulsory taking of parts of property in Australia. A comparative analysis determines if all of the various “harms” that result from coal seam gas occupation are compensable under the current law. The research indicates that “severance” and “injurious affection” are key issues for landholder compensation where CSG plant occupies parts of land; however, the right to claim for “injurious affection” is unclear in the present legislation.
ItemThe Effect of Disturbance Regime on Darwinia glaucophylla (Myrtaceae) and its Habitat(2014-12-29) Booyens, Carmen
The effect of disturbance regime (time since last fire or slashing) on the vulnerable plant species, Darwinia glaucophylla, was assessed on the Central Coast of New South Wales (NSW), Australia. The abundance, growth and flowering of D. glaucophylla adults and abundance and growth of seedlings was measured within sites that had either been recently burnt (≤ 5 years), long unburnt (≥ 14 years) or regularly slashed (30 cm above ground) along a utility easement. Our results showed that Darwinia glaucophylla was most abundant at slashed sites, followed by recently burnt sites; it was present but not abundant at unslashed sites that were burnt ≥ 14 years ago. Seedlings were only found at one, recently burnt site. Disturbance regime had no significant effect on the timing or density of flowering. We found that fruits collected from sites with different disturbance regimes did not germinate after exposure to various combinations of heat, smoke-water and/or scarification. Recently burnt sites contained plants producing a significantly greater number of viable fruits compared to those from other disturbance regimes. Fire and slashing altered the habitat of D. glaucophylla in slightly different ways. The implications of our findings for the management of the species are discussed.
ItemSinglet Levels of the NV− Centre in Diamond(2015-01-27) Rogers, Lachlan J.
The characteristic transition of the NV− centre at 637 nm is between 3A 2 and E 3 triplet states. There are also intermediate A 1 1 and E 1 singlet states, and the infrared transition at 1042 nmbetween these singlets is studied here using uniaxial stress. The stress shift and splitting parameters are determined, and the physical interaction giving rise to the parameters is considered within the accepted electronic model of the centre. It is established that this interaction for the infrared transition is due to a modification of electron–electron Coulomb repulsion interaction. This is in contrast to the visible 637 nm transition where shifts and splittings arise from modification to the one-electron Coulomb interaction. It is also established that a dynamic Jahn–Teller interaction is associated with the singlet E 1 state, which gives rise to a vibronic level 115 cm−1 above the E 1 electronic state. Arguments associated with this level are used to provide experimental confirmation that the A 1 1 is the upper singlet level and E 1 is the lower singlet level.
ItemLong Term Persistence of Nitrosamine-Induced Structural Damage to Heterochromatic DNA(1987-01-01) Stewart, Bernard W.
Different levels of damage and repair to eu- and heterochromatic DNA from the livers of rats receiving a dose of 10 mg/kg N-nitrosodimethylamine (NDMA) were apparent. Preincorporated 3H~thymidine was lost rapidly from euchromatic DNA but persisted in the heterochromatic fraction. Persistent damage, determined as single-stranded regions binding 10 benzoylated DEAE-cellulose (BD-cellulose), was evident in heterochromatic DNA for up to three months. By subjecting rats treated with NDMA to partial hepatectomy, generation of single-stranded regions in the newly synthesized heterochromatic DNA could be demonstrated. Such structural defects were evident when hepatectomy was performed two months after administration of the carcinogen. These findings indicate that structural damage to non-transcribed DNA is one of the most persistent molecular lesions following exposure to nitrosamines.
ItemArrhenius and Armstrong: How Active Opponents in the History of Chemistry Became Major Contributors to Modern Electrolyte Chemistry(2013-01-01) de Berg, Kevin C.
In the late 19th and early 20th centuries Svante Arrhenius and Henry Armstrong understood the dissolution process of salts in water quite differently. Arrhenius saw the dissolution process as one whereby the salt partially dissociated into its ions and Armstrong saw the dissolution process as one whereby the salt associated itself with water. History is somewhat kinder to Arrhenius than it is to Armstrong in that Arrhenius won the Nobel Prize for Chemistry in 1903 for his electrolytic dissociation theory whereas Armstrong was considered of a 'hot air balloon' who made it his business to oppose every new thought in chemistry. In the 1920s Arrhenius' view of partial dissociation was replaced by a view of total dissociation for strong electrolytes with activity and osmotic coefficients being used to account for non-ideal solution behaviour. However, recent research has shown that strong 1:1 electrolytes are best understood by using Arrhenius' original idea of partial dissociation rather than total dissociation and Armstrong's idea of hydration. This strange confluence of factors has important implications for chemical epistemology and its role in chemistry education.
ItemTeaching Chemistry for All Its Worth: The Interaction Between Facts, Ideas, and Language in Lavoisier’s and Priestley’s Chemistry Practice: The Case of the Study of the Composition of Air(2014-10-01) de Berg, Kevin C.
Both Lavoisier and Priestley were committed to the role of experiment and observation in their chemistry practice. According to Lavoisier the physical sciences embody three important ingredients; facts, ideas, and language, and Priestley would not have disagreed with this. Ideas had to be consistent with the facts generated from experiment and observation and language needed to be precise and reflect the known chemistry of substances. While Priestley was comfortable with a moderate amount of hypothesis making, Lavoisier had no time for what he termed theoretical speculation about the fundamental nature of matter and avoided the use of the atomic hypothesis and Aristotle’s elements in his Elements of Chemistry. In the preface to this famous work he claims he has good educational reasons for this position. While Priestley and Lavoisier used similar kinds of apparatus in their chemistry practice, they came to their task with completely different worldviews as regards the nature of chemical reactivity. This paper examines these worldviews as practiced in the famous experiment on the composition of air and the implications of this for chemistry education are considered.