16 research outputs found
Post-Election Violence in Africa: the impact of judicial independence
No full textSimati, Meshack. Post-Election Violence in Africa: The Impact of Judicial Independence. Abingdon, Oxon ; New York, NY: Routledge, 2020. African Governance.This book explores the effect of the judiciary on the incidence of post-election violence by political actors across Africa and within African countries. It examines how variation in judicial independence can constrain or incentivize election violence among democratizing states. Using case studies and cross-national analysis, the book shows that variation in levels of judicial independence from a non-independent judiciary to a quasi-independent judiciary or from a fully independent judiciary to quasi-independent judiciary increases the likelihood of strategic use of post-election violence by non-state actors. However, the likelihood of post-election violence is significantly reduced in non-independent judiciaries or once countries' judiciaries become fully independent. The author makes the theoretical argument that, within unconsolidated states, non-state actors that view the judiciary as semi-independent are more likely to engage in post-election violence with the purpose of creating political and professional uncertainty in order to influence assertive behaviour from judges in disputed elections. Consequently, the book argues that semi-independent judiciaries or judiciaries that are neither fully controlled by the incumbent nor fully independent from the incumbent can help explain post-election violence among unconsolidated states, all else being equal. This book will be of interest to scholars of election violence, democratic politics, law and politics and African politics.This title is available to CSUSM faculty, students, and staff after authentication. Please use the below link to access. https://csu-csusm.userservices.exlibrisgroup.com/view/action/uresolver.do?operation=resolveService&package_service_id=9048709830001672&institutionId=1672&customerId=1670PublishedSimati, Meshack. Post-Election Violence in Africa: The Impact of Judicial Independence. Abingdon, Oxon ; New York, NY: Routledge, 2020. African Governance.978100003585
The substitution behaviour of terpy polyglycoxyl and ruthenium-platinum complexes with biologically significant nucleophiles. A kinetic and mechanistic study.
No full textM. Sc. University of KwaZulu-Natal, Pietermaritzburg 2013.The kinetics of two sets of complexes was investigated under pseudo first order conditions using UV-Visible spectrophotometry as a function of concentration and temperature. The first set consisting 4’-substituted terpy polyglycoxyl complexes reacted with biological relevant N-donor nucleophiles showed that the oxygen on the polyglycoxyl group donates electrons to the Pt-metal resulting in a decrease in reactivity from Pt to Pt(eg). The first carbon-oxygen pendant bond plays a crucial role in regulating the electron density donated because there is insignificant change in the reactivity as the chain length is increased to Pt(deg) and then Pt(teg). The trend in the reactivity slightly increases in general from Pt(eg) to Pt(teg) due to reduction in steric hindrance imposed by the ethylene glycoxy unit on one side of the complex. The reactivity of the nucleophiles is pKa and steric dependent. It can be concluded that reactivity of the metal complexes is mostly electronically controlled while that of the nucleophiles is dependent on the basicity and steric bulk. The obtained kinetic data is supported by the DFT calculations that reveal a less electrophilic Pt(II) metal centre for complexes bearing the 4’-substituent. The temperature dependent studies support an associative mode of activation.
The second set of complexes studied included Ru(III)-Pt(II) complexes with a semi-rigid linker 4’-pyridyl-2,2’:6’,2’’terpyridine (qpy) whose results indicated that increase in the overall charges of the respective complexes is the key reason for the observed increase in the reactivity. Additionally, replacing the cis pyridyl group in Pt1 by Ru(III) polypyridyl to give Pt2 and Pt3 respectively lowers the energy of the LUMO (ԉ*) orbitals. The two qpy groups in the tri-nuclear complex Pt3 only slightly increases the reactivity from that of Pt2 because the qpy groups are in orthogonal positions preventing π-electron communication hence the two Pt(II) centres act independently of each other.
The observed activation parameters for both sets of complexes support an associative mode of substitution. The results of this project elucidate intrinsic, electronic and steric properties of the complexes that might be exploited for medicinal, photophysical or other applications
The rates and mechanisms of substitution from Ru(II) complexes with different non-leaving ligand environments.
No full textDoctoral Degree. University of KwaZulu-Natal, Pietermaritzburg.Results from multiple studies have confirmed that the nature of ligands on the metal centre determines the properties of an anti-cancer agent in a biological environment. Ligands affect solubility, substitution reactivity, stability of compound and product after substitution and the type of interaction between the agent and DNA among others properties. Due to competition for sulphur biomolecules by anti-cancer agents in the cells, substitution reactions of potential anti-cancer metal complexes with biologically relevant ligands sheds light on the possible interaction modes of the Ru(II) complexes and stability of the resulting products. This helps in the design, synthesis and administration of new pharmacological agents and in the concept of chemo-protection. On this basis, the study of rate of substitutions from the Ru(II) complexes by thiourea nucleophiles under pseudo-first order conditions was undertaken. The reactions were studied as a function of concentration and temperature using standard Stopped Flow technique for ultrafast reactions or UV-Visible Spectrophotometer.
The first series of the complexes investigated the role of arene ligands on the rate of substitutions in (aqua)(η6-arene)Ru(II) complexes. The rate of substitution for the tri-aqua Ru(II) complexes was controlled by the π-acceptor ability of the arene ligands. For the complexes bearing 2,2’-bipyridyl co-ligand, the leaving aqua ligands are located trans to the arene ligands. For these complexes, the reactivity increase in accordance to the number and type of alkyl substituents on the η6-arene ligands which donate inductively into the -molecular orbitals, causing increased trans labialisation of the coordinated aquo co-ligand. Compared to the reactivity of tri-aquo complexes, the auxiliary bipyridyl ligands lower the rate of substitution for the later complex by a factor of about 100, due to its steric hindrance at the Ru(II) metal centre. The significantly negative activation entropies and positive activation enthalpies suggest that the activation process is dominated by bond making. In the second study, the role of arene and phosphino ligands on the rate of chloride substitution from Ru (II) complexes containing arene and phosphino co-ligands was investigated. It was observed that the coordinated arene ligand donates electrons towards the Ru(II) metal centre and its -electron cloud presents an electrostatic repulsive effect onto and around the Ru centre as measured by the projected cone angle. The bidentate bis(diphenylphosphino)-methane ligand hinders the approach of nucleophiles during the substitution process. When the bis(diphenylphosphino)methane chelate is expanded through the introduction of a methylene carbon within the bridge, the steric hindrance to the approach of nucleophiles is reduced and
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the ligand assumes a trough like conformation which traps the nucleophile within the coordination sphere. This enhances the reactivity by a factor of 103.
The rate of chloride substitution from 2,4,6-tris-(2-pyridyl)-1,3,5-triazineRu(PPh3)(Cl) and analogous complexes was done in the third study. The study showed that higher π-acceptor ability of cis ligands increase the electrophilicity of the metal centre resulting in enhanced reactivity. Electron donating substituents on the ligands at the cis position lower the π-acceptor ability of the ligand hence lower electrophilicity of the Ru(II) metal centre leading to slower rate of substitution. The investigation on the effect of 2-(2-Pyridyl)azole-based ancillary ligands (L) on the chloride substitution from [RuII(tpy)(L)(Cl)]+ in the fourth study revealed that strong electronegative atoms (O or S) in the auxiliary ligands enhance their π-back-donation capacity thereby increasing the electrophilicity of the metal centre and hence the reactivity. On the other hand, the –NH group donate electron density to the metal centre by outer sphere proton donation causing trans-effect thereby which increases the reactivity more than in the former case. The fifth study sought to understanding the effect of substituents on rate of chloride substitution from Ru(II)tpy complexes. Ru(II)tpy complexes with the tpy having electron donating substituents trans to the labile ligand were dominated by trans-effect while those where the tpy bears electron accepting substituents had enhanced π-back-bonding controlling the reactivity. The rate of substitution from the Ru(II) complexes was more strongly affected by electron donating substituents. Electron donating ligands at the cis position slow down the rate of substitution from the Ru(II) metal centre.
Data from DFT calculations performed using Gaussian09 suite of programmes was used to support the observed rates of substitution from the Ru(II) complexes. Large negative values of entropies of activation and positive enthalpies of activation indicate associative mode of activation. On the other hand small positive values of entropies of activation indicate dissociatively activate interchange mode of substitutions. The studies were explored on model Ru(II) complexes with bio-relevant thiourea nucleophiles to predict possible interaction with biomolecules which has become part of the methods used in the endeavour to search for alternative anti-cancer agents with improved efficacy and higher spectrum of activity
The rate of substitution from η6-arene ruthenium(II) complexes
No full textThe rate and mechanism of substitution in the Ru(II) complexes (C1–C6) by thiourea nucleophiles was studied at pH 2 and rate constants measured as a function of nucleophile concentrations and temperature using spectrometric methods. There is increased electron density at the Ru metal atom of C2 as a result of inductive donation by substituents on the arene ligand, making it less positive and therefore less reactive than C1. For the complexes C3–C6 bearing the 2,2′-bipyridyl ligand, the aqua ligands are located trans to the arene ligands, and hence, their reactivity increases in accordance to the number and type of alkyl substituents on the η6-arene ligands which donate inductively into the π-molecular orbitals, causing increased trans labialisation of the coordinated aquo co-ligand. Compared to the reactivity of triaquo complex (C1), the auxiliary bipyridyl ligand of (C3) complex lowers the rate of substitution for the later complex by a factor of about 100, possibly due to its steric hindrance at the Ru(II) metal centre. The significantly negative activation entropies and positive activation enthalpies suggest an associative mode of substitution. The reactivity of the nucleophiles follow the order DMTU > TU > TMTU.Funding was provided by South African Agency for Science and Technology Advancement and University of KwaZulu-Natal (Inyuvesi Yakwazulu-Natali)
The effect of substituents on the reactivity of dichloridotriphenylphosphinoruthenium(II) complexes: kinetic and mechanistic study
No full textThe rates of substitution of chloro ligands from a series of ruthenium(II) complexes, [Ru(κ3-L)(PPh3)Cl2] (L = 2,2′:6′,2′′-terpyridine, 1; 4′-(4-methylphenyl)-2,2′:6′,2′′-terpyridine, 2; 4,4′4″-tri-tert-butyl-2,2′:6′,2′′-terpyridine, 3; 4′-(4-chlorophenyl)-2,2′:6′,2′′-terpyridine, 4; 4-chloro-2,2′:6′,2′′-terpyridine, 5 and 2,6-bis(2-pyrazolyl)pyridine, 6), by thiourea nucleophiles was investigated under pseudo-first-order conditions in methanol as a function of nucleophile concentration and temperature. The chloro ligands were substituted in two steps and the reactivity trend was 4 > 5 > 2 > 1 > 6. Complexes 2 and 3 having donor substituents on the 2,2′:6′,2′′-terpyridine backbone experience a trans-effect making them more reactive than 1. Complexes 4 and 5 are more reactive than 1 due to enhanced π-back-bonding brought about by electron-withdrawing substituents on their 2,2′:6′,2′′-terpyridine backbones. The reactivity of 4 is higher than 5 due to greater electron acceptor-ability of the chlorophenyl substituent than the chloro substituent in 5. The 2,6-bis(pyrazolyl)pyridine ligand in 6 retards the reactivity of the complex compared to 1 due to the cis-donor effect of the pyrazole. The reactivity of the complexes is associative for all nucleophiles in step one and only thiourea in step two. The substitution reactions proceed by a steady changeover from an associative interchange mechanism (Ia) to a dissociative interchange (Id) mechanism on increasing steric hindrance.This research was funded by the University of KwaZulu Natal South Africa
Tuning the reactivity of ruthenium(II) terpyridyl complexes using auxiliary ligands: kinetic and mechanistic studies
No full textSubstitution behavior of the labile aqua ligand in four mononuclear ruthenium(II) terpyridyl complexes with different auxiliary N (pyridine) (Ru1), N^N (2,2′-bipyridyl (Ru2), 2′-(2-pyridyl)quinoline (Ru3), 2,2′-biqunoline (Ru4) ligands was investigated using three nucleophiles; thiourea, 1,1-dimethylthiourea and 1,1,3,3-tetramethylthiourea. The effect of concentration and temperature on the substitution behavior of the complexes were studied under pseudo-first order conditions using UV–Vis spectrophotometer. The second order rate constants (k2) of the aqua complexes decreased in the order: Ru4 > Ru3 > Ru1 > Ru2. The results showed that the rate of substitution of the aqua ligand increased with an increase in the π-surface area of the N^N bidentate auxiliary ligands. This is attributable to an upsurge in π-back-donation and electrophilicity of the complexes as the π-extension of the auxiliary ligands increases. Ru2 is less reactive than Ru1 due to the increased steric hinderance introduced by the 2,2′-bipyridyl bidentate auxiliary ligand in Ru2 compared to Ru1 which has two independent trans pyridines. From computational results, it was observed that as the aromatic surface area of the auxiliary ligand increased from Ru1–Ru4, the HOMO–LUMO gap decreased accordingly. Consequently, the chemical softness and electrophilicity of the complexes increased accordingly. This is corroborated by the decrease in pKa values of the complexes as one moves from Ru1 to Ru4. As a result, the nucleophilic attack becomes facile from Ru1 to Ru4. All the reactions follow an associative interchange mechanism as indicated by the positive activation enthalpy and negative activation entropy. The crystal structure of bipyridylterpyridylthiourearuthenium(II) perchlorate show that the substitution product obtained is stable
A Quality Improvement Project of Music Program to Improve Social Functioning for Patients with Alzheimer’s Disease
No full textPurpose of the Project: Music programs are proven to work in the population with Alzheimer's and can help improve social function (Zhang et al., 2017). Despite findings, practice gap continues to affect the quality of music programs reducing overall benefits. The music program at the project site is not standardized and is provided to all patients, without clear goals, frequency, and methods to track & assess benefits. As a result, the program is not fully exploited, and benefits not ascertained. The purpose of this project is to review, track, assess, and standardize music program in a defined frequency, and goal to improve social function in three areas including relationship, communication and time spent between patients diagnosed with Alzheimer’s disease. Methodology:Charts were drawn from Electronic Medical Record (EMR) and sampled using a convenient sampling to identify a sample size of 30 participants, 55 years and older, diagnosed with Alzheimer’s disease. A retrospective chart review was conducted to Identify areas of quality improvement in the administration and documentation of music, a plan was made, and music administered over a period of one month, following which a prospective chart review was done to ascertain improvement in social function. Results:pre-implementation social function total mean was 20.40 (SD =7.54) with spending time having a mean of 5.43 (SD =4.26), communication a mean of 10.23 (SD =2.96), and relationship a mean of 4.73 (SD =2.70). The post-implementation social function total mean was 20.59 (SD =7.10) with spending time having a mean of 5.93 (SD =3.80), communication a mean of 9.93 (SD =3.14), and relationship a mean of 4.72 (SD =2.55). The Z-score difference between pre and post implementation for spending time was -2.837, with a p value of .005; for communication was -1.414, with a p value of.157; for relationship was -1.000, with a p value of .317; and total social function Z score was -1.997, with a p value of .046. Implications for Practice: Improvement in spending of time increased social function and was mainly influenced by staff increased activity and participation in bringing out patients to the sessions and the encouragement of patients to attend recreational sessions; Staff activity in bringing patient out to socialize with others can improve overall socialization.D.N.P.Includes bibliographical referencesIncludes vit
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Post-Election Violence in Africa ::the impact of judicial independence /
No full textThis book explores the effect of the judiciary on the incidence of post-election violence by political actors across Africa and within African countries. It examines how variation in judicial independence can constrain or incentivize election violence among democratizing states. Using case studies and cross-national analysis, the book shows that variation in levels of judicial independence from a non-independent judiciary to a quasi-independent judiciary or from a fully independent judiciary to quasi-independent judiciary increases the likelihood of strategic use of post-election violence by non-state actors. However, the likelihood of post-election violence is significantly reduced in non-independent judiciaries or once countries' judiciaries become fully independent. The author makes the theoretical argument that, within unconsolidated states, non-state actors that view the judiciary as semi-independent are more likely to engage in post-election violence with the purpose of creating political and professional uncertainty in order to influence assertive behaviour from judges in disputed elections. Consequently, the book argues that semi-independent judiciaries or judiciaries that are neither fully controlled by the incumbent nor fully independent from the incumbent can help explain post-election violence among unconsolidated states, all else being equal. This book will be of interest to scholars of election violence, democratic politics, law and politics and African politics
Recommended from our members
Post-election violence in Africa ::the impact of judicial independence /
No full textThis book explores the effect of the judiciary on the incidence of post-election violence by political actors across Africa and within African countries. It examines how variation in judicial independence can constrain or incentivize election violence among democratizing states. Using case studies and cross-national analysis, the book shows that variation in levels of judicial independence from a non-independent judiciary to a quasi-independent judiciary or from a fully independent judiciary to quasi-independent judiciary increases the likelihood of strategic use of post-election violence by non-state actors. However, the likelihood of post-election violence is significantly reduced in non-independent judiciaries or once countries' judiciaries become fully independent. The author makes the theoretical argument that, within unconsolidated states, non-state actors that view the judiciary as semi-independent are more likely to engage in post-election violence with the purpose of creating political and professional uncertainty in order to influence assertive behaviour from judges in disputed elections. Consequently, the book argues that semi-independent judiciaries or judiciaries that are neither fully controlled by the incumbent nor fully independent from the incumbent can help explain post-election violence among unconsolidated states, all else being equal. This book will be of interest to scholars of election violence, democratic politics, law and politics and African politics
The influence of α,α′-diimine bridging ligand on the reactivity of binuclear para-cymene ruthenium(II) complexes. Kinetic, mechanistic and computational study
No full textSubstitution kinetics of the aqua ligands in four binuclear ruthenium(II) para-cymene complexes with different α,α′-diimine bridging ligands [2-pyridylaldazine (Ru-1), p-phenylenebis(picoline)aldimine (Ru-2), p-biphenylenebis(picoline)aldimine (Ru-3) and p-xylenebis(picoline)aldimine (Ru-4)] was investigated as a function of nucleophile concentration and temperature under pseudo-first order conditions using thiourea nucleophiles. The rates of the simultaneous substitution of the aqua ligands decreased in the order: Ru-1 > Ru-4 > Ru-3 > Ru-2. The reactivity of the complexes is controlled by the inherent electronic and steric contributions of the bridging ligand. The strong π-acceptor bridging ligand is responsible for the high reactivity observed in Ru-1 compared to the rest of the complexes. From Ru-2 to Ru-4, the reactivity increases with decrease in steric congestion around the metal centres. The cage effect plays a role in the enhanced reactivity of Ru-4 compared to Ru-3 and Ru-2. Reactivity trends are excellently supported by computational results. All the complexes showed a stepwise deprotonation of the coordinated aqua ligands except Ru-4 and the pKa values increased from Ru-1 to Ru-4 due to progressive increase in σ-donicity of the spacers. The activation parameters (ΔH≠ > 0, ΔS≠ < 0) obtained for all the complexes support an associative mechanism of activation
