Creating novel ligand libraries from air-stable, chiral primary phosphines

PhD ThesisThe fearsome reputation of primary phosphines, many of which are toxic and highly reactive towards atmospheric oxygen, has constrained the use of these versatile compounds in synthetic chemistry. However, a few examples of user-friendly stable primary phosphines have been reported which owe their stability to high steric encumbrance or is as yet unexplained. Recently an electronic stabilisation has allowed for the synthesis of novel MOPtype phosphorus ligands with previously inaccessible architectures that have potential applications in homogeneous asymmetric catalysis; an introduction into the topic is given in Chapter 1. The first air-stable chiral primary phosphines 1a,b were developed in our labs. We subsequently simplified and improved the synthetic approach to afford these and previously unreported synthons on a multigram scale, which is described in Chapter 2. Phosphiranes are highly strained heterocycles with a small sum of bond angles at the phosphorus (Σ°(P): <260). They act as ligands with interesting properties upon metal complexation due to the unusual electronics they possess as a result of the imposed ring strain; this leads to high s-character at the phosphorus and both lowered HOMO and LUMO energy levels compared to their acyclic counterparts. In Chapter 3 we report the synthesis of chiral binaphthyl-phosphirane ligands 14a,b offering high thermal and air stability, as well as the synthesis and solid state structures of their platinum(II) dichloride complexes. Initial findings for the application of the phosphiranes in the palladium catalysed asymmetric hydrosilylation of styrene are discussed. Furthermore, we were able to synthesise MOP-dimethylphosphine, MOP-bis(dimethylamino) phosphine and MOP-dimethylphosphonite ligands in one-pot reactions from 1a,b. Their peculiar structural and electronic parameters, in addition to those of MOP-phosphiranes 14a,b, are discussed in Chapter 4. The coordination chemistry of these compounds was investigated on platinum(II) and palladium(II) metals elucidating their cis/trans influences III and aryl side-on coordination respectively. We also carried out comparative studies in the allylic alkylation of (rac)-(E)-1,3-diphenylallyl acetate and the hydrosilylation of styrene, utilising palladium complexes of those MOP-type ligands as asymmetric catalysts. In Chapter 5 we report the efficient synthesis of novel MOP-phosphonite hybrid ligands 33a,b and 34a,b which incorporate two binaphthyl groups around the single phosphonite P-donor. We present their methallylpalladium complexes, which were studied in detail both in the solid-state and in solution. The palladium catalysed asymmetric hydrosilylation of styrene was again carried out and the results analysed in view of the molecular structure of the ligands. Furthermore, rhodium complexes of the same ligands were investigated, in particular with a view to examining their binding behaviour towards the metal. An unusual aromatic side-on binding mode was revealed by X-ray crystallography and further elucidated in solution by extended NMR experiments. Solution NMR studies also revealed a dynamic behaviour of these complexes, triggered by the hemilabile binding of the ligands towards the metal centre. Finally, we describe the synthesis of novel MOP-phosphonodichalcogenoite and MOP-phosphaalkene ligands in Chapter 6. Their corresponding gold(I) complexes were prepared and representative examples were characterised by X-ray diffraction. For the MOP-phosphonodiselenoite derivatives we also report the characteristic 77Se NMR data.financial support that was provided by Lee through his EPSRC grant, which allowed me to present my work at the ACS National Meeting 2011 in Anaheim (CA, USA), and the Dalton Transactions Younger Researchers Symposium 2011 at the University of Warwick (UK); I was also able to get funding awarded by PhoSciNet (COST action CM0802) to deliver an oral presentation at the 9th European Workshop on Phosphorus Chemistry 2012 in Rennes (France)

Is land reform working? A critical evaluation of the Bergland Development Trust (BDT) land reform project in Porterville, Western Cape

Magister Artium (Development Studies) - MA(DVS)Land reform is currently high on the agenda of the current government. This is because many people believe that land reform is a valuable tool in addressing the land question and combating poverty in South Africa. It is also evident that government and experts on land reform are clear that in order to enhance land reform in the country, the land must be used to improve the livelihoods of those who need it the most. It is also pivotal that land reform is successful in order to ensure food security. It is important to evaluate these types of land reform models in order to gain valuable insights and lessons that can enhance successful land reform projects in the country that can also serve as a manual for farmers and governments. Although much research focuses on the failure of land reform projects, this research focuses on a successful land redistribution programme that improved the livelihoods of rural people. More specifically, this research critically evaluated the Bergland Development Trust (BDT) land reform project in the Porterville region in the Western Cape province of South Africa. The BDT land reform project is a joint venture between the workers of the Berghoff Farm and their employer, the farmer who also served as a valuable mentor to them. My research found that BDT land reform project improved the livelihoods of the beneficiaries of the project. The BDT beneficiaries earn a sustainable income which, in turn, helps them to buy clothes, vehicles, and enrol their children at the local former ‘Model C’ school. Furthermore, active participation in the project has enhanced the self-image and bargaining power of the beneficiaries which, in turn, extended their livelihoods base. This study is guided by the sustainable livelihoods approach to development. This study critically analysed the factors contributing to their successes and also explored the lessons it holds for other land reform projects. A qualitative research design was employed in order to obtain the necessary data for the research. The data was collected by means of semi-structured interviews and questionnaires with the management of the Bergland Development Trust land reform project. After a critical assessment of the BDT land reform project, the recommendations will be forwarded to the Local Government and other projects that will benefit from the experiences of the BDT land reform project

Projeto de fundações por sapatas rígidas dimensionadas por software estrutural verificado por metodologia manual

O tema deste Trabalho de Conclusão de Curso é executar um projeto de fundações de sapatas rígidas, considerando o dimensionamento geotécnico e estrutural. O principal objetivo é fazer o dimensionamento de 18 sapatas rígidas isoladas por método computacional com uso de software estrutural, fazendo a verificação, por meio de comparação com a metodologia manual, com emprego de soluções tradicionais de dimensionamento. O método computacional é realizado através do software estrutural TQS, versão 21, modo estudantil, no aplicativo interno TQS Fundações. O estudo da metodologia manual foi feito a partir da elaboração de planilha eletrô- nica para facilitar os cálculos. Por tratar-se de um software estrutural, o dimensionamento geotécnico (determinação das tensões admissíveis e recalques) deve ser feito em paralelo. Embora o software seja automatizado, foi necessário informar a tensão admissível do solo, sendo esta obtida a partir da média das tensões admissíveis determinadas pela metodologia manual. A média das tensões foi utilizada justamente por não se conhecer os locais reais das localizações dos ensaios SPT, caso existisse esta informação o correto seria utilizar valores com ponderação com relação à distância das sapatas aos furos do ensaio de SPT. Inicialmente foi feita a análise do comportamento do solo, com o objetivo de determinar os parâmetros a partir de ensaios de simples reconhecimento (SPT). Depois, foi realizado o cálculo das tensões admissíveis no solo por métodos teórico e semiempíricos. Além disso, a determinação dos recalques, necessários para a verificação do estado limite de serviços (ELS), foi feito pela metodologia manual. Após o dimensionamento geotécnico, foi feito o dimensionamento estrutural pelas duas metodologias (software e manual) seguindo as verificações exigidas em normas como NBR 6118 (ABNT, 2014) e NBR 6122 (ABNT, 2019). No comparativo das duas metodologias, verificou-se as áreas das fundações e as áreas de aço calculadas e utilizadas, bem como os quantitativos de material (volume de concreto e peso de aço). Pelas análises, verifica-se que as áreas das funda- ções e de aço são equivalentes em ambas as metodologias, validando a aplicação do software. A diferença entre o volume de concreto foi de 3,17%, sendo a maior quantidade de concreto registrada pela metodologia analítica. Em termos de somatório de seção e de massa de aço empregada, a maior quantidade de aço foi registrada pelo software e a diferença foi de 5,38% e 27%, com relação aos métodos manuais. Ao final é apresentada a concepção do projeto (detalhamento) efetuado pelo software.The theme of this study is the design of rigid foundations, considering geotechnical and structural aspects. The main objective is the design of 18 footings using structural software, verifying by comparison manual method. The computational method is performed using the structural software TQS, version 21, student license, using its “TQS Fundações” module. The manual method was carried out with electronic spreadsheet to facilitate processes. The software, since it primarily for structural design, geotechnical design must be prepared outside the software. Although the software is fully functional, it was necessary to inform the admissible soil strength, which is obtained from the arithmetic mean of values determined by manual methodology. The manual methodology begins with the analysis of the soil behavior, with the objective of determining, from Standard Penetration Test (SPT), the soil parameters. After that, the admissible soil strength is calculated based on theorical and semiempirical methods. Moreover, the vertical deformation, used to verify the service state limit (SSL), was carried out only with the manual methodology. Finally, the structural design, validation was made based on the standards NBR 6118 (2014) and NBR 6122 (ABNT, 2019). The comparison of the two methods, Computational and Manual, was made by verifying the base area of the footings and the section area of steel in the quantitatives (concrete volume and steel weight). The area of footings and of section steel were considered almost equal, validating the use of the software. The difference between the concrete volume between the methods was 3.7%, Manual method being slightly higher. The difference between steel section area and weight in the two methods were 5,38% and 27%, respectively, Computational method being higher. The details of the design, made by the software, are presented

Detection of Chemical Warfare Agents with a Miniaturized High-Performance Drift Tube Ion Mobility Spectrometer Using High-Energetic Photons for Ionization

A growing demand for low-cost gas sensors capable of detecting the smallest amounts of highly toxic substances in air, including chemical warfare agents (CWAs) and toxic industrial chemicals (TICs), has emerged in recent years. Ion mobility spectrometers (IMS) are particularly suitable for this application due to their high sensitivity and fast response times. In view of the preferred mobile use of such devices, miniaturized ion drift tubes are required as the core of IMS-based lightweight, low-cost, hand-held gas detectors. Thus, we evaluate the suitability of a miniaturized ion mobility spectrometer featuring an ion drift tube length of just 40 mm and a high resolving power of Rp= 60 for the detection of various CWAs, such as nerve agents sarin (GB), tabun (GA), soman (GD), and cyclosarin (GF), as well as the blister agent sulfur mustard (HD), the blood agent hydrogen cyanide (AC) and the choking agent chlorine (CL). We report on the limits of detection reaching minimum concentration levels of, for instance, 29 pptvfor sarin (GB) within an averaging time of only 1 s. Furthermore, we investigate the effects of precursors, simulants, and other common interfering substances on false positive alarms

Real‐time remote detection of airborne chemical hazards – an unmanned aerial vehicle (UAV) carrying an ion mobility spectrometer

Rapidly detecting and identifying chemical agents after a chemical release is crucial for a reliable assessment of imminent risks and provides the initial basis for defining an adequate level of protection for first responders. An unmanned / uncrewed aerial vehicle (UAV) equipped with gas detectors may quickly explore the contaminated area without exposing any first responders to the yet unknown threat. However, UAVs possess limitations in their capability concerning payload, operational range, and power requirements. Choosing the appropriate gas sensors for this application, thus, imposes significant technical challenges. In this work, we present a mobile ion mobility spectrometer (IMS) designed for operation with UAVs. The IMS is equipped with a dedicated closed gas loop, high-performance driver electronics, and wireless data transmission capabilities. The resulting performance of the UAV-mounted mobile IMS is characterized in the lab with the chemical warfare agents (CWAs) sarin (GB), tabun (GA), soman (GD), cyclosarin (GF), and sulfur mustard (HD), and further evaluated in three different field-testing scenarios using the simulation compound di(propylene glycol) methyl ether (DPM). It is thereby used to monitor the area near (i) a point source continuously emitting small quantities of a gaseous chemical, (ii) a point source suddenly releasing a limited quantity of a chemical as an aerosol, and (iii) a minor contamination of a liquid chemical on the ground. The results obtained in this work enable a well-founded estimation of the capabilities and limitations of the UAV-mounted mobile IMS concerning the real-time remote detection of chemical hazards such as CWAs

Genetic Epidemiology of Attention Deficit Hyperactivity Disorder (ADHD Index) in Adults

Context: In contrast to the large number of studies in children, there is little information on the contribution of genetic factors to Attention Deficit Hyperactivity Disorder (ADHD) in adults. Objective: To estimate the heritability of ADHD in adults as assessed by the ADHD index scored from the CAARS (Conners’ Adult ADHD Rating Scales). Design: Phenotype data from over 12,000 adults (twins, siblings and parents) registered with the Netherlands Twin Register were analyzed using genetic structural equation modeling. Main outcome measures: Heritability estimates for ADHD from the twin-family study. Results: Heritability of ADHD in adults is estimated around 30 % in men and women. There is some evidence for assortative mating. All familial transmission is explained by genetic inheritance, there is no support for the hypothesis that cultural transmission from parents to offspring is important. Conclusion: Heritability for ADHD features in adults is present, but is substantially lower than it is in children

Balancing Structure and Flexibility in the Project Process - A Case Study of Project Management at Where Is My Pony

The practice of project management has been used by organizations for many years and different philosophies have emerged. Among the philosophies is both traditional and modern project management as well as project management practices integrating sustainability. However, its implications for smaller and creative organizations are limited in research. Advertising agencies are creative organizations that primarily work project-based, and the use of project management practices have been identified important for project success. Nonetheless, how project management is used within advertising agencies has been poorly identified and how they can implement sustainability into these practices is non-evident. The aim of this research is therefore to investigate how an advertising agency works in their project process. Looking into the Gothenburg-based organization Where Is My Pony and how their projects process is constructed and how sustainability is integrated in it, gives empirical evidence to how smaller creative organizations work in projects. By further investigating improvement areas it gives implications both to theory and practice in how to successfully manage projects as an advertising agency. To conduct this research a case study was performed by interviewing all employees at Where Is My Pony along with some of their clients. The empirical findings are analyzed in combination with the literature on the topic and aid in demonstrating how an advertising agency can construct and improve their project process while integrating sustainability as a foundation. This study establishes that there is a gap in the literature as well as in practice in how to best integrate sustainability into projects for small creative organizations. Nevertheless, it is concluded that it is paramount that the project process at Where Is My Pony balances a distinctive project process, that includes sustainability in every step and guides the framework for the creative work, while still enable a flexible element to be able to meet the clients need. Thereby this research gives contributions both to practice and theory, by creating an understanding how advertising agencies could design their project management process while integrating sustainability

Is land reform working? A critical evaluation of the Bergland Development Trust (BDT) land reform project in Porterville, Western Cape

Magister Artium (Development Studies) - MA(DVS)Land reform is currently high on the agenda of the current government. This is because many people believe that land reform is a valuable tool in addressing the land question and combating poverty in South Africa. It is also evident that government and experts on land reform are clear that in order to enhance land reform in the country, the land must be used to improve the livelihoods of those who need it the most. It is also pivotal that land reform is successful in order to ensure food security. It is important to evaluate these types of land reform models in order to gain valuable insights and lessons that can enhance successful land reform projects in the country that can also serve as a manual for farmers and governments. Although much research focuses on the failure of land reform projects, this research focuses on a successful land redistribution programme that improved the livelihoods of rural people. More specifically, this research critically evaluated the Bergland Development Trust (BDT) land reform project in the Porterville region in the Western Cape province of South Africa. The BDT land reform project is a joint venture between the workers of the Berghoff Farm and their employer, the farmer who also served as a valuable mentor to them. My research found that BDT land reform project improved the livelihoods of the beneficiaries of the project. The BDT beneficiaries earn a sustainable income which, in turn, helps them to buy clothes, vehicles, and enrol their children at the local former ‘Model C’ school. Furthermore, active participation in the project has enhanced the self-image and bargaining power of the beneficiaries which, in turn, extended their livelihoods base. This study is guided by the sustainable livelihoods approach to development. This study critically analysed the factors contributing to their successes and also explored the lessons it holds for other land reform projects. A qualitative research design was employed in order to obtain the necessary data for the research. The data was collected by means of semi-structured interviews and questionnaires with the management of the Bergland Development Trust land reform project. After a critical assessment of the BDT land reform project, the recommendations will be forwarded to the Local Government and other projects that will benefit from the experiences of the BDT land reform project