Spin crossover in dinuclear iron(II) complexes bridged by bis-bipyridine ligands: dimer effects on electronic structure, spectroscopic properties and spin-state switching.

Inspired by the well-studied mononuclear spin crossover compound [Fe(H2B(pz)2)2(bipy)], the bipyridine-based bisbidentate ligands 1,2-di(2,2'-bipyridin-5-yl)ethyne (ac(bipy)2) and 1,4-di(2,2'-bipyridine-5-yl)-3,5-dimethoxybenzene (Ph(OMe)2(bipy)2) are used to bridge two [Fe(H2B(pz)2)2] units, leading to the charge-neutral dinuclear iron(II) compounds [{Fe(H2B(pz)2)2}2 µ-(ac(bipy)2)] (1) and [{Fe(H2B(pz)2)2}2 µ-(Ph(OMe)2(bipy)2)] (2), respectively. The spin-crossover properties of these molecules are investigated by temperature-dependent PPMS measurements, Mössbauer, vibrational and UV/Vis spectroscopy as well as X-ray absorption spectroscopy. While compound 1 undergoes complete SCO with T1/2 = 125 K, an incomplete spin transition is observed for 2 with an inflection point at 152 K and a remaining high-spin fraction of 40% below 65 K. The spin transitions of the dinuclear compounds are also more gradual than for the parent compound [Fe(H2B(pz)2)2(bipy)]. This is attributed to steric hindrance between the molecules, limiting intermolecular interactions such as π-π-stacking.

Haematological malignancy in the intensive care unit: microbiology results and mortality.

BACKGROUND: Mortality prediction models of patients with a haematological malignancy admitted to an intensive care unit (ICU) do not include the presence of neutropenia and microbiology results. We performed a registry-based retrospective study of haematology patients admitted to the ICU to investigate the relation between neutropenia, microbiology results and outcome of these patients. METHODS: Neutropenia and microbiology culture results within 24 h before or after ICU admission of patients with a haematological malignancy admitted between 2004 and 2010 were described and analysed for association with 28-day mortality. RESULTS: We identified 234 individual patients with a current malignant haematological condition, of which 27% were neutropenic and 21% had a positive blood culture at admission. Most prevalent from blood cultured species were Escherichia coli and coagulase-negative staphylococci. The overall 28-day mortality was 38%. In patients with a positive blood culture but no neutropenia, 28-day mortality was 28% and in patients with neutropenia but without positive blood culture, it was 36%. The 28-day mortality of patients with both neutropenia and a positive blood culture was 55% with an adjusted (for APACHE-II score) hazard ratio (HR) of 1.8 (95%CI 1.0-3.4) compared to other hematologic patients admitted to the ICU. CONCLUSION: In patients with haematological malignancy admitted to the ICU, culture results are diverse. The combination of neutropenia and positive blood culture is associated with increased 28-day mortality. We suggest this could be of additional value when assessing mortality risk in this patient group.