Synthetic Challenges toward Modeling Formate Dehydrogenases Using [WVI≡S] Complexes Supported by a Tetradentate [N2S2]4- Ligand.

This report documents our attempts at synthesizing a terminal [WVI≡S] complex supported by a tetradentate, diamido/dithiolate ligand ([N2S2]4-). The target compound was selected because it would serve as a synthetic model for the active sites of formate dehydrogenase (FDH) enzymes. Although the desired [N2S2]WVI≡S species was observed as an NEt3 adduct by mass spectrometry in one case, generally unwanted side reactions prevented isolation and definitive characterization of the target compound. Instead, isolated products characterized by X-ray crystallography included {[N2S2]H}WVI(S2)Cl from redox chemistry of the terminal sulfide, ([N2S2]WVI)2(µ-[N2S2]) from dissociation of the terminal sulfide, ({[N2S2]H}WV)2(µ-S)2 from metal reduction and µ-sulfide bridge formation, and {[N2S2]H}2 from disulfide bond formation via thiolate redox chemistry. A product formed from adventitious exposure to air/moisture, {[N2S2]H2}WVI(O)2, was also characterized. The diverse range of products formed simply from attempted metalation of the [N2S2]4- ligand with Cl4WVI≡S highlights the synthetic challenges toward building active sites that are structurally faithful to FDH.

Poor Health Behaviour in Medical Students at a South African University: A Cross-Sectional Survey Study.

BACKGROUND: Personal health behaviours and lifestyle habits of health professionals influence their counselling practices related to non-communicable diseases (NCDs). There are limited data on the prevalence of unhealthy lifestyle habits among medical students and the impact of acquired health knowledge throughout the curriculum. The aim of this study was to determine and compare the prevalence of modifiable behavioural NCD risk factors of medical students in different academic years at a South African tertiary institution. METHODS: A cross-sectional observational study of 532 consenting medical students was conducted. Participants completed five online questionnaires regarding lifestyle behaviours (physical activity, dietary habits, smoking, alcohol consumption and sleep). RESULTS: Lifestyle-related risk factors with the highest prevalence were poor sleep quality (66.0%), low levels of habitual physical activity (55.8%) and low-to-moderate diet quality (54.5%). There were no differences between academic years for all risk factors measured. Over 60% of the cohort had two or more NCD risk factors and this prevalence did not differ across the degree program with the acquisition of more health knowledge. CONCLUSION: Medical students have a high prevalence of poor sleep quality, low levels of physical activity and low-to-moderate diet quality, which does not appear to change over the course of their academic career. Sleep hygiene, regular physical activity and healthy nutrition should be targeted in intervention programmes and be more prevalent in the medical curriculum.

Feasibility of Provision and Vaccine Hesitancy at a Central Hospital COVID-19 Vaccination Site in South Africa after Four Waves of the Pandemic.

BACKGROUND: As mortality declined significantly during the fourth and fifth waves compared to previous waves, the question of the future role of COVID-19 vaccination arose among both experts and the public in South Africa. Turning attention away from the general public, now considered to be at very low risk of severe COVID-19 disease, a commonly held view was that the vaccination campaign should focus only on those who remain highly vulnerable to severe disease and death from COVID-19. Primary amongst this group are patients with common chronic diseases attending hospital outpatient departments. We hypothesized that providing COVID-19 vaccinations on-site at a central hospital will increase uptake for the patients with co-morbid chronic conditions who need them most in the Omicron phase of the pandemic. AIM: Evaluate the acceptability, need, and uptake of a hospital-based vaccination site for patients attending the medical hospital outpatient departments. OBJECTIVES: To assess vaccination uptake, coverage, and hesitancy in people attending a central hospital, to determine factors associated with and influencing vaccination uptake, and to document implementation and assess acceptability of the vaccination project among staff and persons attending the hospital. METHODS: Mixed-methods study using quantitative and qualitative methods. RESULTS: Of the 317 participants enrolled in the study, 229 (72%) had already received at least one dose of the COVID-19 vaccine. A total of 296 participants were eligible for a first vaccination, additional vaccination, or booster vaccination according to the South African Department of Health guidelines. Of those previously vaccinated, 65% opted for an additional dose on the day it was offered (same day). Only 13 previously unvaccinated participants (15% of vaccine naïve participants) opted for vaccination, increasing vaccine coverage with at least one dose from 72% to 76%. Approximately 24% (n = 75) of all participants refused vaccination (vaccine hesitant). Variables tested for an association with vaccination status demonstrated that age reached statistical significance. Emerging themes in the qualitative analysis included perceptions of vulnerability, vaccine safety and efficacy concerns, information gaps regarding vaccinations, the value of convenience in the decision to vaccinate, and the role of health promoters. CONCLUSIONS: This study has shown that it is logistically acceptable to provide a vaccination site at a large hospital targeting patients attending outpatient services for chronic medical conditions. This service also benefits accompanying persons and hospital staff. Access and convenience of the vaccination site influence decision-making, increasing the opportunity to vaccinate. However, vaccine hesitancy is widespread with just under one-quarter of all those offered vaccinations remaining unvaccinated. Strengthening health education and patient-clinician engagement about the benefits of vaccination is essential to reach highly vulnerable populations routinely attending hospital outpatient departments with an appropriate vaccination program.

Adolescent maternal mortality at a district health services over a five year period in South Africa: A retrospective study.

OBJECTIVE: To determine the trend in adolescent maternal deaths and deliveries over a period of 5 years and 9 months (July 2014-March 2020) at the Ekurhuleni Health District in South Africa. METHODS: The present study was a retrospective review and secondary data analysis using data from the District Health Information System and clinical oversight data from the District Clinical Specialist Team. The study population was adolescent pregnant women aged 10-19 years who died at health facilities. Descriptive and inferential statistics were used for analysis. RESULTS: There was a total of 12 559 adolescent deliveries. Adolescent birth rate was lower than that of sub-Saharan Africa. Adolescent deaths (n = 37) contributed to around 8% of the total maternal deaths. Deliveries (97%) and deaths (98%) were most common among women aged 15-19 years. Six (16%) women had a repeat pregnancy. A total of 21 (57%) had booked for antenatal care. There were few antenatal visits (mean 4 ± SD 2.1). The main three causes of death were hypertension (35%) followed by hemorrhage (24%) and suicide (14%). Postpartum deaths (62%) were significantly (chi-square test, P = 0.02) higher than antepartum deaths (38%). The majority (73%) of newborns were born alive which was significantly (chi-square test, P = 0.002) higher than those which were stillborn (27%). CONCLUSION: The main challenges were the high number of adolescent deliveries, repeat pregnancies, and preventable causes of death. Multidisciplinary collaboration involving obstetricians, midwives, pediatricians, school health services, social workers and psychologists is indispensable for comprehensive management, prioritizing pregnancy prevention among this vulnerable group.

Reactivity of a Dithiocarbamate-Ligated [WVI≡S] Complex with Hydride Donors: Toward a Synthetic Mimic of Formate Dehydrogenase.

Formate dehydrogenase (FDH) enzymes catalyze redox interconversion of CO2 and HCO2-, with a key mechanistic step being the transfer of H- from HCO2- to an oxidized active site featuring a [MVI≡S] group in a sulfur-rich environment (M = Mo or W). Here, we report reactivity studies with HCO2- and other reducing agents of a synthetic [WVI≡S] model complex ligated by dithiocarbamate (dtc) ligands. Reactions of [WVIS(dtc)3][BF4] (1) conducted in MeOH solvent generated [WVIS(S2)(dtc)2] (2) and [WVS(µ-S)(dtc)]2 (3) products by a solvolysis pathway that was accelerated by the presence of [Me4N][HCO2] but did not require it. Under MeOH-free conditions, the reaction of 1 with [Et4N][HCO2] produced some [WIV(µ-S)(µ-dtc)(dtc)]2 (4), but predominantly [WV(dtc)4]+ (5), along with stoichiometric CO2 detected by headspace gas chromatography (GC) analysis. Stronger hydride sources such as K-selectride generated the more reduced analogue, 4, exclusively. The reaction of 1 with the electron donor, CoCp2, also produced 4 and 5 in varying amounts depending on reaction conditions. These results indicate that formates and borohydrides act as electron donors rather than hydride donors toward 1, an outcome that diverges from the behavior of FDHs. The difference is ascribed to the more oxidizing potential of [WVI≡S] complex 1 when supported by monoanionic dtc ligands that allows electron transfer to outcompete hydride transfer, as compared to the more reduced [MVI≡S] active sites supported by dianionic pyranopterindithiolate ligands in FDHs.

COVID-19 severity and in-hospital mortality in an area with high HIV prevalence.

Background: HIV infection causes immune dysregulation affecting T-cell and monocyte function, which may alter coronavirus disease 2019 (COVID-19) pathophysiology. Objectives: We investigated the associations among clinical phenotypes, laboratory biomarkers, and hospitalisation outcomes in a cohort of people hospitalised with COVID-19 in a high HIV prevalence area. Method: We conducted a prospective observational cohort study in Tshwane, South Africa. Respiratory disease severity was quantified using the respiratory oxygenation score. Analysed biomarkers included inflammatory and coagulation biomarkers, CD4 T-cell counts, and HIV-1 viral loads (HIVVL). Results: The analysis included 558 patients, of whom 21.7% died during admission. The mean age was 54 years. A total of 82 participants were HIV-positive. People living with HIV (PLWH) were younger (mean age 46 years) than HIV-negative people; most were on antiretroviral treatment with a suppressed HIVVL (72%) and the median CD4 count was 159 (interquartile range: 66-397) cells/µL. After adjusting for age, HIV was not associated with increased risk of mortality during hospitalisation (age-adjusted hazard ratio = 1.1, 95% confidence interval: 0.6-2.0). Inflammatory biomarker levels were similar in PLWH and HIV-negative patients. Detectable HIVVL was associated with less severe respiratory disease. In PLWH, mortality was associated with higher levels of inflammatory biomarkers. Opportunistic infections, and other risk factors for severe COVID-19, were common in PLWH who died. Conclusion: PLWH were not at increased risk of mortality and those with detectable HIVVL had less severe respiratory disease than those with suppressed HIVVL. What this study adds: This study advances our understanding of severe COVID-19 in PLWH.

Crystal Structure of the [FeFe]-Hydrogenase Maturase HydE Bound to Complex-B.

[FeFe]-hydrogenases use a unique organometallic complex, termed the H cluster, to reversibly convert H2 into protons and low-potential electrons. It can be best described as a [Fe4S4] cluster coupled to a unique [2Fe]H center where the reaction actually takes place. The latter corresponds to two iron atoms, each of which is bound by one CN- ligand and one CO ligand. The two iron atoms are connected by a unique azadithiolate molecule (-S-CH2-NH-CH2-S-) and an additional bridging CO. This [2Fe]H center is built stepwise thanks to the well-orchestrated action of maturating enzymes that belong to the Hyd machinery. Among them, HydG converts l-tyrosine into CO and CN- to produce a unique l-cysteine-Fe(CO)2CN species termed complex-B. Very recently, HydE was shown to perform radical-based chemistry using synthetic complex-B as a substrate. Here we report the high-resolution crystal structure that establishes the identity of the complex-B-bound HydE. By triggering the reaction prior to crystallization, we trapped a new five-coordinate Fe species, supporting the proposal that HydE performs complex modifications of complex-B to produce a monomeric "SFe(CO)2CN" precursor to the [2Fe]H center. Substrate access, product release, and intermediate transfer are also discussed.

Challenges in the Synthesis of Active Site Mimics for [NiFe]-Hydrogenases.

One of the more active areas in bioorganometallic chemistry is the preparation and reactivity studies of active site mimics of the [NiFe]-hydrogenases. One area of particular recent progress involves reactions that interconvert Ni(µ-X)Fe centers for X = OH, H, CO, as described by Song et al. Such reactions illustrate new ways to access intermediates related to the Ni-R and Ni-SI states of the enzyme. Most models are derivatives of the type (diphosphine)Ni(SR)2Fe(CO)3-n(PR'3)n. In recent work, the methodology has been generalized to include FeII(diphosphine) derivatives of Ni(N2S2), where N2S22- is the tetradentate diamine-dithiolate (CH2N(CH3)CH2CH2S-)2. Indeed, models based on Ni(N2S2) have proven valuable, but these studies also highlight challenges in working with heterobimetallic complexes, specifically the tendency of some such Ni-Fe complexes to convert to homometalliic Ni-Ni derivatives. This kind of problem is not readily detected by X-ray crystallography. With this caution in mind, we argue that one series of complexes recently described in this journal are almost certainly misassigned.

Response to the Novel Corona Virus (COVID-19) Pandemic Across Africa: Successes, Challenges, and Implications for the Future.

BACKGROUND: The COVID-19 pandemic has already claimed considerable lives. There are major concerns in Africa due to existing high prevalence rates for both infectious and non-infectious diseases and limited resources in terms of personnel, beds and equipment. Alongside this, concerns that lockdown and other measures will have on prevention and management of other infectious diseases and non-communicable diseases (NCDs). NCDs are an increasing issue with rising morbidity and mortality rates. The World Health Organization (WHO) warns that a lack of nets and treatment could result in up to 18 million additional cases of malaria and up to 30,000 additional deaths in sub-Saharan Africa. OBJECTIVE: Document current prevalence and mortality rates from COVID-19 alongside economic and other measures to reduce its spread and impact across Africa. In addition, suggested ways forward among all key stakeholder groups. OUR APPROACH: Contextualise the findings from a wide range of publications including internet-based publications coupled with input from senior-level personnel. ONGOING ACTIVITIES: Prevalence and mortality rates are currently lower in Africa than among several Western countries and the USA. This could be due to a number of factors including early instigation of lockdown and border closures, the younger age of the population, lack of robust reporting systems and as yet unidentified genetic and other factors. Innovation is accelerating to address concerns with available equipment. There are ongoing steps to address the level of misinformation and its consequences including fines. There are also ongoing initiatives across Africa to start addressing the unintended consequences of COVID-19 activities including lockdown measures and their impact on NCDs including the likely rise in mental health disorders, exacerbated by increasing stigma associated with COVID-19. Strategies include extending prescription lengths, telemedicine and encouraging vaccination. However, these need to be accelerated to prevent increased morbidity and mortality. CONCLUSION: There are multiple activities across Africa to reduce the spread of COVID-19 and address misinformation, which can have catastrophic consequences, assisted by the WHO and others, which appear to be working in a number of countries. Research is ongoing to clarify the unintended consequences given ongoing concerns to guide future activities. Countries are learning from each other.

Review of Ongoing Activities and Challenges to Improve the Care of Patients With Type 2 Diabetes Across Africa and the Implications for the Future.

BACKGROUND: There has been an appreciable increase in the number of people in Africa with metabolic syndrome and Type 2 diabetes (T2DM) in recent years as a result of a number of factors. Factors include lifestyle changes, urbanisation, and the growing consumption of processed foods coupled with increasing levels of obesity. Currently there are 19 million adults in Africa with diabetes, mainly T2DM (95%), estimated to grow to 47 million people by 2045 unless controlled. This has a considerable impact on morbidity, mortality and costs in the region. There are a number of issues to address to reduce the impact of T2DM including improving detection rates and current access to services alongside addressing issues of adherence to prescribed medicines. There are also high rates of co-morbidities with infectious diseases such as HIV and tuberculosis in patients in Africa with T2DM that require attention. OBJECTIVE: Document ongoing activities across Africa to improve the care of patients with T2DM especially around issues of identification, access, and adherence to changing lifestyles and prescribed medicines. In addition, discussing potential ways forward to improve the care of patients with T2DM based on ongoing activities and experiences including addressing key issues associated with co-morbidities with infectious diseases. OUR APPROACH: Contextualise the findings from a wide range of publications including internet based publications of national approaches coupled with input from senior level government, academic and other professionals from across Africa to provide future guidance. ONGOING ACTIVITIES: A number of African countries are actively instigating programmes to improve the care of patients with T2DM starting with improved diagnosis. This recognises the growing burden of non-communicable diseases across Africa, which has been neglected in the past. Planned activities include programmes to improve detection rates and address key issues with diet and lifestyle changes, alongside improving monitoring of care and activities to enhance adherence to prescribed medicines. In addition, addressing potential complexities involving diabetes patients with infectious disease co-morbidities. It is too early to fully assess the impact of such activities. CONCLUSION: There are a number of ongoing activities across Africa to improve the management of patients with diabetes including co-morbidities. However, more needs to be done considering the high and growing burden of T2DM in Africa. Ongoing research will help further benefit resource allocation and subsequent care.

Ongoing and planned activities to improve the management of patients with Type 1 diabetes across Africa; implications for the future.

BACKGROUND: Currently about 19 million people in Africa are known to be living with diabetes, mainly Type 2 diabetes (T2DM) (95%), estimated to grow to 47 million people by 2045. However, there are concerns with early diagnosis of patients with Type 1 diabetes (T1DM) as often patients present late with complications. There are also challenges with access and affordability of insulin, monitoring equipment and test strips with typically high patient co-payments, which can be catastrophic for families. These challenges negatively impact on the quality of care of patients with T1DM increasing morbidity and mortality. There are also issues of patient education and psychosocial support adversely affecting patients' quality of life. These challenges need to be debated and potential future activities discussed to improve the future care of patients with T1DM across Africa. METHODOLOGY: Documentation of the current situation across Africa for patients with T1DM including the epidemiology, economics, and available treatments within public healthcare systems as well as ongoing activities to improve their future care. Subsequently, provide guidance to all key stakeholder groups going forward utilizing input from senior-level government, academic and other professionals from across Africa. RESULTS: Whilst prevalence rates for T1DM are considerably lower than T2DM, there are concerns with late diagnosis as well as the routine provision of insulin and monitoring equipment across Africa. High patient co-payments exacerbate the situation. However, there are ongoing developments to address the multiple challenges including the instigation of universal health care and partnerships with non-governmental organizations, patient organizations, and pharmaceutical companies. Their impact though remains to be seen. In the meantime, a range of activities has been documented for all key stakeholder groups to improve future care. CONCLUSION: There are concerns with the management of patients with T1DM across Africa. A number of activities has been suggested to address this and will be monitored.

Proactive Measures to Combat a SARS-CoV-2 Transmission Among High Risk Patients and Health Care Workers in an Outpatient Dialysis Facility.

Background: End-stage-renal-failure (ESRF) patients attending clustered out-patient dialysis are susceptible to SARS-CoV-2 infection. Comorbidities render them vulnerable to severe COVID-19. Although preventative and mitigation strategies are recommended, the effect of these are unknown. A period of "potential-high-infectivity" results if a health-care-worker (HCWs) or a patient becomes infected. Aim: We describe and analyze early, universal SARS-CoV-2 real time reverse transcription polymerase chain reaction (RT-PCR) tests, biomarker monitoring and SARS-CoV-2 preventative strategies, in a single dialysis center, after a positive patient was identified. Methodology: The setting was a single outpatient dialysis center in Johannesburg, South Africa which had already implemented preventative strategies. We describe the management of 57 patients and 11 HCWs, after one of the patients tested positive for SARS-CoV-2. All individuals were subjected to RT-PCR tests and biomarkers (Neutrophil-Lymphocyte Ratio, C-reactive protein, and D-Dimer) within 72 h (initial-tests). Individuals with initial negative RT-PCR and abnormal biomarkers (one or more) were subjected to repeat RT-PCR and biomarkers (retest subgroup) during the second week. Additional stringent measures (awareness of viral transmission, dialysis distancing and screening) were implemented during the period of "potential high infectivity." The patient retest subgroup also underwent clustered dialysis until retest results became available. Results: A second positive-patient was identified as a result of early universal RT-PCR tests. In the two positive-patients, biomarker improvement coincided with RT-PCR negative tests. We identified 13 individuals for retesting. None of these retested individuals tested positive for SARS-CoV-2 and there was no deterioration in median biomarker values between initial and retests. Collectively, none of the negative individuals developed COVID-19 symptoms during the period "potential high infectivity." Conclusion: A SARS-CoV-2 outbreak may necessitate additional proactive steps to counteract spread of infection. This includes early universal RT-PCR testing and creating further awareness of the risk of transmission and modifying preventative strategies. Abnormal biomarkers may be poorly predictive of SARS-CoV-2 infection in ESRF patients due to underlying illnesses. Observing dynamic changes in biomarkers in RT-PCR positive and negative-patients may provide insights into general state of health.

Influence of nitro substituents on the redox, electronic, and proton reduction catalytic behavior of phenolate-based [N2O3]-type cobalt(iii) complexes.

We report on the synthesis, redox, electronic, and catalytic behavior of two new cobalt(iii) complexes, namely [CoIII(L1)MeOH] (1) and [CoIII(L2)MeOH] (2). These species contain nitro-rich, phenolate-based pentadentate ligands and present dramatically distinct properties associated with the position in which the -NO2 substituents are installed. Species 1 displays nitro-substituted phenolates, and exhibits irreversible redox response and negligible catalytic activity, whereas 2 has fuctionalized phenylene moieties, shows much improved redox reversibility and catalytic proton reduction activity at low overpotentials. A concerted experimental and theoretical approach sheds some light on these drastic differences.

Synthetic Designs and Structural Investigations of Biomimetic Ni-Fe Thiolates.

Described are the syntheses of several Ni(µ-SR)2Fe complexes, including hydride derivatives, in a search for improved models for the active site of [NiFe]-hydrogenases. The nickel(II) precursors include (i) nickel with tripodal ligands: Ni(PS3)- and Ni(NS3)- (PS33- = tris(phenyl-2-thiolato)phosphine, NS33- = tris(benzyl-2-thiolato)amine), (ii) traditional diphosphine-dithiolates, including chiral diphosphine R,R-DIPAMP, (iii) cationic Ni(phosphine-imine/amine) complexes, and (iv) organonickel precursors Ni( o-tolyl)Cl(tmeda) and Ni(C6F5)2. The following new nickel precursor complexes were characterized: PPh4[Ni(NS3)] and the dimeric imino/amino-phosphine complexes [NiCl2(PCH═NAn)]2 and [NiCl2(PCH2NHAn)]2 (P = Ph2PC6H4-2-). The iron(II) reagents include [CpFe(CO)2(thf)]BF4, [Cp*Fe(CO)(MeCN)2]BF4, FeI2(CO)4, FeCl2(diphos)(CO)2, and Fe(pdt)(CO)2(diphos) (diphos = chelating diphosphines). Reactions of the nickel and iron complexes gave the following new Ni-Fe compounds: Cp*Fe(CO)Ni(NS3), [Cp(CO)Fe(µ-pdt)Ni(dppbz)]BF4, [( R,R-DIPAMP)Ni(µ-pdt)(H)Fe(CO)3]BArF4, [(PCH═NAn)Ni(µ-pdt)(Cl)Fe(dppbz)(CO)]BF4, [(PCH2NHAn)Ni(µ-pdt)(Cl)Fe(dppbz)(CO)]BF4, [(PCH═NAn)Ni(µ-pdt)(H)Fe(dppbz)(CO)]BF4, [(dppv)(CO)Fe(µ-pdt)]2Ni, {H[(dppv)(CO)Fe(µ-pdt)]2Ni]}BF4, and (C6F5)2Ni(µ-pdt)Fe(CO)2(dppv) (DIPAMP = (CH2P(C6H4-2-OMe)2)2; BArF4- = [B(C6H3-3,5-(CF3)2]4-)) Within the context of Ni-(SR)2-Fe complexes, these new complexes feature new microenvironments for the nickel center: tetrahedral Ni, chirality, imine, and amine coligands, and Ni-C bonds. In the case of {H[(dppv)(CO)Fe(µ-pdt)]2Ni}+, four low-energy isomers are separated by ≤3 kcal/mol, one of which features a biomimetic HNi(SR)4 site, as supported by density functional theory calculations.

Ni(ii) complexes of the phosphine-oxime Ph2PC6H4-2-CH[double bond, length as m-dash]NOH.

We report the solution and structural chemistry of nickel(ii) complexes of the phosphine-oxime Ph2PC6H4-2-CH[double bond, length as m-dash]NOH (PCH[double bond, length as m-dash]NOH). PCH[double bond, length as m-dash]NOH invariably binds in a bidentate manner as illustrated by cis-Ni(PCH[double bond, length as m-dash]NOH)2Cl2 and cis-[Ni(PCH[double bond, length as m-dash]NOH)2]2+ (as its BF4- salt). Treatment of PCH[double bond, length as m-dash]NOH with Ni(OAc)2(H2O)4 gave charge-neutral trans-[Ni(PCH[double bond, length as m-dash]NO)2]0. Treatment of trans-[Ni(PCH[double bond, length as m-dash]NO)2]0 with BF3 gave [Ni(PCH[double bond, length as m-dash]NO)2BF2]BF4. The cation features a planar NiP2N2 center wherein the pair of oximate groups are linked by the difluoroboryl center. The 1 : 1 complexes of the oxime and the oximate are illustrated by [Ni(PCH[double bond, length as m-dash]NOH)Cl2]2 and [Ni(C6F5)(PCH[double bond, length as m-dash]NO)]2, which feature five- and four-coordinate Ni(ii) centers, respectively. All complexes in this series hydrolyze to give the trinickel oxo-phosphine-oximate complex [Ni3(PCH[double bond, length as m-dash]NO)3O]+. One feature of the PCH[double bond, length as m-dash]NOH ligand is its wide bite angle combined with its protic OH center. These aspects are manifested in the structures of Ni(PCH[double bond, length as m-dash]NOH)2Cl2 and [Ni(PCH[double bond, length as m-dash]NOH)Cl2]2, which show intramolecular hydrogen bonding to terminal chloride ligands.

Framing preventive care messaging and cervical cancer screening in a health-insured population in South Africa: Implications for population-based communication?

The impact of health message framing on cervical cancer screening uptake is poorly understood. In a prospective randomized control study with 748 females, aged 21-65 years with no Pap smear in the previous 3 years, they randomly received a loss-framed, gain-framed, or neutral health message (control) regarding cervical cancer screening by email. Screening rate in the control group was 9.58 percent (CI: 9.29%-9.87%), 5.71 percent (CI: 5.48%-6.98%) in the gain-framed group, and 8.53 percent (CI: 8.24%-8.81%) in the loss-framed group. Statistically there was no difference between the three screening rates. Framing of health messages may not be a significant consideration when communicating through emails.

Evaluation of the coordination preferences and catalytic pathways of heteroaxial cobalt oximes towards hydrogen generation.

Three new heteroaxial cobalt oxime catalysts, namely [CoIII(prdioxH)(4tBupy)(Cl)]PF6 (1), [CoIII(prdioxH)(4Pyrpy)(Cl)]PF6 (2), and [CoIII(prdioxH)(4Bzpy)(Cl)]PF6 (3) have been studied. These species contain chloro and substituted tert-butyl/pyrrolidine/benzoyl-pyridino ligands axially coordinated to a trivalent cobalt ion bound to the N4-oxime macrocycle (2E,2'E,3E,3'E)-3,3'-(propane-1,3-diylbis(azanylylidene))bis(butan-2-one)dioxime, abbreviated (prdioxH)- in its monoprotonated form. Emphasis was given to the spectroscopic investigation of the coordination preferences and spin configurations among the different 3d6 CoIII, 3d7 CoII, and 3d8 CoI oxidation states of the metal, and to the catalytic proton reduction with an evaluation of the pathways for the generation of H2via CoIII-H- or CoII-H- intermediates by mono and bimetallic routes. The strong field imposed by the (prdioxH)- ligand precludes the existence of high-spin configurations, and 6-coordinate geometry is favored by the LSCoIII species. Species 1 and 3 show a split CoIII/CoII electrochemical wave associated with partial chemical conversion to a [CoIII(prdioxH)Cl2] species, whereas 2 shows a single event. The reduction of these CoIII complexes yields LSCoII and LSCoI species in which the pyridine acts as the dominant axial ligand. In the presence of protons, the catalytically active CoI species generates a CoIII-H- hydride species that reacts heterolytically with another proton to generate dihydrogen. The intermediacy of a trifluoroacetate-bound CoIII/CoII couple in the catalytic mechanism is proposed. These results allow for a generalization of the behavior of heteroaxial cobalt macrocycles and serve as guidelines for the development of new catalysts based on macrocyclic frameworks.

Distinct Proton and Water Reduction Behavior with a Cobalt(III) Electrocatalyst Based on Pentadentate Oximes.

A new pentadentate oxime has been designed to drive the preferential coordination favored by Co(I) in catalysts used for proton/water reduction. The ligand incorporates water upon metal coordination and is water soluble. This Co(III) species is doubly reduced to Co(I) and exhibits H(+) reduction activity in the presence of weak acids in MeCN and evolves H2 upon protonation suggesting that the ligand design increases catalyst effectiveness. Superior catalysis is observed in water with a turnover number (TON) of 5700 over 18 h. However, the catalyst yields Co-based nanoparticles, indicating that the solvent media may dictate the nature of the catalyst.

Modulation of electronic and redox properties in phenolate-rich cobalt(III) complexes and their implications for catalytic proton reduction.

We investigate the redox, spectroscopy and catalytic reactivity of new cobalt(iii) complexes based on phenolate-rich [N2O3] ligands. These complexes are described as [Co(III)(L(X))MeOH], where X indicates the presence of chloro (), bromo (), iodo (), or tert-butyl () substituents in the 3(rd) and 5(th) positions of each phenolate ring. These substituents modulate the Co(iii) ← PheO(-) LMCT bands of the parent complexes with (451) > (453) > (456) > (468 nm) and the redox potentials involved with the Co(iii)/Co(ii) and ligand reduction and with the phenolate/phenoxyl oxidation processes. The influence of the substituents on the phenolate pendant arms was also observed on the kinetic parameters; presented a rate constant of 1.0 × 10(-3) s(-1) whereas showed a considerably slower rate (5.3 × 10(-5) s(-1)). Species and are electrocatalysts towards proton reduction in the presence of weak acid in acetonitrile. A TON of 10.8 was observed for after 3 h of bulk electrolysis at -2.20 VFc/Fc(+) using a mercury pool as the working electrode.

Ligand transformations and efficient proton/water reduction with cobalt catalysts based on pentadentate pyridine-rich environments.

A series of cobalt complexes with pentadentate pyridine-rich ligands is studied. An initial Co(II) amine complex 1 is prone to aerial oxidation yielding a Co(III) imine complex 2 that is further converted into an amide complex 4 in presence of adventitious water. Introduction of an N-methyl protecting group to the ligand inhibits this oxidation and gives rise to the Co(II) species 5. Both the Co(III) 4 and Co(II) 5 show electrocatalytic H2 generation in weakly acidic media as well as in water. Mechanisms of catalysis seem to involve the protonation of a Co(II)-H species generated in situ.