Generation and Reactivity of Polychalcogenide Chains in Binuclear Cobalt(II) Complexes

A series of six binuclear Co(II)–thiolate complexes, [Co2(BPMP)(S–C6H4-o-X)2]1+ (X = OMe, 2; NH2, 3), [Co2(BPMP)(μ-S–C6H4-o-O)]1+ (4), and [Co2(BPMP)(μ-Y)]1+ (Y = bdt, 5; tdt, 6; mnt, 7), has been synthesized from [Co2(BPMP)(MeOH)2(Cl)2]1+ (1a) and [Co2(BPMP)(Cl)2]1+ (1b), where BPMP1– is the anion of 2,6-bis[[bis(2-pyridylmethyl)amino]methyl]-4-methylphenol. While 2 and 3 could allow the two-electron redox reaction of the two coordinated thiolates with elemental sulfur (S8) to generate [Co2(BPMP)(μ-S5)]1+ (8), the complexes, 4–7, could not undergo a similar reaction. An analogous redox reaction of 2 with elemental selenium ([Se]) produced [{Co2(BPMP)(μ-Se4)}{Co2(BPMP)(μ-Se3)}]2+ (9a) and [Co2(BPMP)(μ-Se4)]1+ (9b). Further reaction of these polychalcogenido complexes, 8 and 9a/9b, with PPh3 allowed the isolation of [Co2(BPMP)(μ-S)]1+ (10) and [Co2(BPMP)(μ-Se2)]1+ (11), which, in turn, could be converted back to 8 and 9a upon treatment with S8 and [Se], respectively. Interestingly, while the redox reaction of the polyselenide chains in 9a and 11 with S8 produced 8 and [Se], the treatment of 8 with [Se] gave back only the starting material (8), thus demonstrating the different redox behavior of sulfur and selenium. Furthermore, the reaction of 8 and 9a/9b with activated alkynes and cyanide (CN–) allowed the isolation of the complexes, [Co2(BPMP)(μ-E2C2(CO2R)2)]1+ (E = S: 12a, R = Me; 12b, R = Et; E = Se: 13a, R = Me; 13b, R = Et) and [Co2(BPMP)(μ-SH)(NCS)2] (14), respectively. The present work, thus, provides an interesting synthetic strategy, interconversions, and detailed comparative reactivity of binuclear Co(II)–polychalcogenido complexes

Factors associated with one-step TST positivity among HCWs in four chest diseases hospitals, Bangladesh, 2013 (N = 731).

Factors associated with one-step TST positivity among HCWs in four chest diseases hospitals, Bangladesh, 2013 (N = 731).</p

Factors associated with incident TST positivity among healthcare workers in four chest diseases hospitals, Bangladesh, 2013–2016.

Factors associated with incident TST positivity among healthcare workers in four chest diseases hospitals, Bangladesh, 2013–2016.</p

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BackgroundHealthcare workers (HCWs) are at increased risk of tuberculosis infection (TBI). We estimated the prevalence and incidence of TBI and risk factors among HCWs in Bangladeshi hospitals to target TB infection prevention and control (IPC) interventions.MethodsDuring 2013–2016, we conducted a longitudinal study among HCWs in four chest disease hospitals. At baseline, we administered a questionnaire on sociodemographic and occupational factors for TB, tuberculin skin tests (TST) in all hospitals, and QuantiFERON ®-TB Gold in-Tube (QFT-GIT) tests in one hospital. We assessed factors associated with baseline TST positivity (induration ≥10mm), TST conversion (induration increase ≥10mm from baseline), baseline QFT-GIT positivity (interferon-gamma ≥0.35 IU/mL), and QFT-GIT conversion (interferon-gamma ResultsOf the 758 HCWs invited, 732 (97%) consented to participate and 731 completed the one-step TST, 40% had a positive TST result, and 48% had a positive QFT-GIT result. In multivariable models, HCWs years of service 11–20 years had 2.1 (95% CI: 1.5–3.0) times higher odds of being TST-positive and 1.6 (95% CI 1.1–2.5) times higher odds of QFT-GIT-positivity at baseline compared with those working ≤10 years. HCWs working 11–20 years in pulmonary TB ward had 2.0 (95% CI: 1.4–2.9) times higher odds of TST positivity, and those >20 years had 2.5 (95% CI: 1.3–4.9) times higher odds of QFT-GIT-positivity at baseline compared with those working ConclusionsPrevalent TST and QFT-GIT positivity was associated with an increased number of years working as a healthcare worker and in pulmonary TB wards. The incidence of TBI among HCWs suggests ongoing TB exposure in these facilities and an urgent need for improved TB IPC in chest disease hospitals in Bangladesh.</div

Study flow chart.

BackgroundHealthcare workers (HCWs) are at increased risk of tuberculosis infection (TBI). We estimated the prevalence and incidence of TBI and risk factors among HCWs in Bangladeshi hospitals to target TB infection prevention and control (IPC) interventions.MethodsDuring 2013–2016, we conducted a longitudinal study among HCWs in four chest disease hospitals. At baseline, we administered a questionnaire on sociodemographic and occupational factors for TB, tuberculin skin tests (TST) in all hospitals, and QuantiFERON ®-TB Gold in-Tube (QFT-GIT) tests in one hospital. We assessed factors associated with baseline TST positivity (induration ≥10mm), TST conversion (induration increase ≥10mm from baseline), baseline QFT-GIT positivity (interferon-gamma ≥0.35 IU/mL), and QFT-GIT conversion (interferon-gamma ResultsOf the 758 HCWs invited, 732 (97%) consented to participate and 731 completed the one-step TST, 40% had a positive TST result, and 48% had a positive QFT-GIT result. In multivariable models, HCWs years of service 11–20 years had 2.1 (95% CI: 1.5–3.0) times higher odds of being TST-positive and 1.6 (95% CI 1.1–2.5) times higher odds of QFT-GIT-positivity at baseline compared with those working ≤10 years. HCWs working 11–20 years in pulmonary TB ward had 2.0 (95% CI: 1.4–2.9) times higher odds of TST positivity, and those >20 years had 2.5 (95% CI: 1.3–4.9) times higher odds of QFT-GIT-positivity at baseline compared with those working ConclusionsPrevalent TST and QFT-GIT positivity was associated with an increased number of years working as a healthcare worker and in pulmonary TB wards. The incidence of TBI among HCWs suggests ongoing TB exposure in these facilities and an urgent need for improved TB IPC in chest disease hospitals in Bangladesh.</div

Factors associated with prevalent QFT-GIT positivity among healthcare workers in Hospital D, Bangladesh, 2013–2016.

Factors associated with prevalent QFT-GIT positivity among healthcare workers in Hospital D, Bangladesh, 2013–2016.</p

Factors associated with incident QFT-GIT positivity among healthcare workers by exposures in hospital D, Bangladesh, 2013–2016.

Factors associated with incident QFT-GIT positivity among healthcare workers by exposures in hospital D, Bangladesh, 2013–2016.</p

Baseline characteristics of healthcare workers at four chest diseases hospitals in Bangladesh, 2013.

Baseline characteristics of healthcare workers at four chest diseases hospitals in Bangladesh, 2013.</p

Cumulative age-specific viral etiology of hospitalized children with respiratory illness aged <5 years enrolled in the four surveillance hospitals, Bangladesh, 2010–2014.

<p>Cumulative age-specific viral etiology of hospitalized children with respiratory illness aged <5 years enrolled in the four surveillance hospitals, Bangladesh, 2010–2014.</p

Monthly distribution of total number of enrolled hospitalized children with respiratory symptoms andproportion of children with respiratory symptoms positive for respiratory syncytial virus, human metapneumovirus, parainfluenza, influenza, adenovirus and rhinovirus infection in the four surveillance hospitals, Bangladesh, 2010–2014.

<p>Monthly distribution of total number of enrolled hospitalized children with respiratory symptoms andproportion of children with respiratory symptoms positive for respiratory syncytial virus, human metapneumovirus, parainfluenza, influenza, adenovirus and rhinovirus infection in the four surveillance hospitals, Bangladesh, 2010–2014.</p