The surprising lability of bis(2,2’:6’,2’’-terpyridine)- chromium(III) complexes

The complex [Cr(tpy)(O3SCF3)3] (tpy = 2,2′:6′,2′′-terpyridine) is readily made from [Cr(tpy)Cl3] and is a convenient precursor to [Cr(tpy)2][PF6]3 and to [Cr(tpy)(4′-(4-tolyl)tpy)][PF6]3 and [Cr(tpy)(5,5′′-Me2tpy)][PF6]3 (4′-(4-tolyl)tpy = 4′-(4-tolyl)-2,2′:6′,2′′-terpyridine; 5,5′′-Me2tpy = 5,5′′-dimethyl-2,2′:6′,2′′-terpyridine); these are the first examples of heteroleptic bis(tpy) chromium(III) complexes. The single crystal structures of 2{[Cr(tpy)2][PF6]3}·5MeCN, [Cr(tpy)(4′-(4-tolyl)tpy)][PF6]3·3MeCN and [Cr(tpy)(5,5′′-Me2tpy)][PF6]3·3MeCN have been determined. Each cation contains the expected octahedral {Cr(tpy)2}3+ unit; in all three structures, the need to accommodate three anions per cation and the solvent molecules prevents the formation of a grid-like array of cations that is typical of many lattices containing {M(tpy)2}2+ motifs. Three reversible electrochemical processes are observed for [Cr(tpy)(4′-(4-tolyl)tpy)][PF6]3 and [Cr(tpy)(5,5′′-Me2tpy)][PF6]3, consistent with those documented for [Cr(tpy)2]3+. At pH 6.36, aqueous solutions of [Cr(tpy)2][PF6]3 are stable for at least two months. However, contrary to the expectations of the d3 Cr3+ ion being a kinetically inert metal centre, the tpy ligands in [Cr(tpy)2]3+are labile in the presence of base; absorption and 1H NMR spectroscopies have been used to monitor the effects of adding NaOH to aqueous and CD3OD solutions, respectively, of the homo- and heteroleptic complexes. Ligand dissociation is also observed when [Bu4N]F is added to CD3OD solutions of the complexes, but in aqueous solution, [Cr(tpy)2][PF6]3 is stable in the presence of fluoride ion

Symmetry as a new element to control molecular switches

The isomerization properties of an azocarbazole macrocycle in solution were investigated utilizing NMR spectroscopy with in situ irradiation in combination with DFT calculations. It was demonstrated that the position of azo units in a rigid macrocyclic system influences the photoisomerization pathway even if the initial all-E isomer is highly symmetric. Furthermore, the effect of ring strain on lowering the rates of thermal isomerization was demonstrated and a mechanism via an inversion-rotation proposed. The herein presented results and methods give new insights into the general nature of the azobenzene unit. In particular we illustrate the effect of symmetry changes due to macrocyclic arrangement on the photochemical and thermal isomerization properties, which will stimulate future development towards multinary molecular switches

Heteroleptic chromium(III) tris(diimine) [Cr(N^N)2(N'^N')]3+ complexes

A series of heteroleptic tris(diimine) complexes of chromium(III) is reported and the crystal structures of {4[Cr(bpy)2(phen)][PF6]3}·11MeCN and 4[Cr(4,4′-Me2bpy)2(bpy)][PF6]3}·12MeCN·H2O are described. The combined effects of a 1:3 cation: anion ratio and lattice solvent molecules are discussed, in particular in the context of the influence on intercation embraces. The presence of the methyl substituents in {4[Cr(4,4′-Me2bpy)2(bpy)][PF6]3}·12MeCN·H2O results in Me–πbpy contacts becoming the dominant packing interactions and in the assembly of motifs distinct from those in {4[Cr(bpy)2(phen)][PF6]3}·11MeCN

Comparison of control charts for monitoring clinical performance using binary data.

BACKGROUND: Time series charts are increasingly used by clinical teams to monitor their performance, but statistical control charts are not widely used, partly due to uncertainty about which chart to use. Although there is a large literature on methods, there are few systematic comparisons of charts for detecting changes in rates of binary clinical performance data. METHODS: We compared four control charts for binary data: the Shewhart p-chart; the exponentially weighted moving average (EWMA) chart; the cumulative sum (CUSUM) chart; and the g-chart. Charts were set up to have the same long-term false signal rate. Chart performance was then judged according to the expected number of patients treated until a change in rate was detected. RESULTS: For large absolute increases in rates (>10%), the Shewhart p-chart and EWMA both had good performance, although not quite as good as the CUSUM. For small absolute increases (<10%), the CUSUM detected changes more rapidly. The g-chart is designed to efficiently detect decreases in low event rates, but it again had less good performance than the CUSUM. IMPLICATIONS: The Shewhart p-chart is the simplest chart to implement and interpret, and performs well for detecting large changes, which may be useful for monitoring processes of care. The g-chart is a useful complement for determining the success of initiatives to reduce low-event rates (eg, adverse events). The CUSUM may be particularly useful for faster detection of problems with patient safety leading to increases in adverse event rates.  

Change in Health-related Quality of Life After Referral to Memory Assessment Services

: Despite strong support for the provision of memory assessment services (MASs) in England and other countries, their effectiveness in improving patient outcomes is uncertain. We aimed to describe change in patients' health-related quality of life (HRQL) 6 months after referral to MASs and to examine associations with patient characteristics and use of postdiagnostic interventions. Data from 883 patients referred to 69 MASs and their informal caregivers (n=569) were collected at referral and 6 months later. Multivariable linear regression was used to examine associations of change in HRQL (DEMQOL, DEMQOL-Proxy) with patient characteristics (age, sex, ethnicity, socioeconomic deprivation, and comorbidity) and use of postdiagnostic interventions (antidementia medications and nonpharmacological therapies). Mean HRQL improved, irrespective of diagnosis: self-reported HRQL increased 3.4 points (95% CI, 2.7-4.1) and proxy-reported HRQL 1.3 points (95% CI, 0.5-2.1). HRQL change was not associated with any of the patient characteristics studied. Patients with dementia (54%) receiving antidementia drugs reported greater improvement in their HRQL but those using nonpharmacological therapies reported less improvement compared with those note receiving therapy. HRQL improved in the first 6 months after referral to MASs. Research is needed to determine longer term sustainability of the benefits and the cost-effectiveness of MASs.<br/

Aphasic Confrontation Naming Elaboration

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The impact of a national clinician-led audit initiative on care and mortality after hip fracture in England: an external evaluation using time trends in non-audit data.

BACKGROUND: Hip fracture is the most common serious injury of older people. The UK National Hip Fracture Database (NHFD) was launched in 2007 as a national collaborative, clinician-led audit initiative to improve the quality of hip fracture care, but has not yet been externally evaluated. METHODS: We used routinely collected data on 471,590 older people (aged 60 years and older) admitted with a hip fracture to National Health Service (NHS) hospitals in England between 2003 and 2011. The main variables of interest were the use of early surgery (on day of admission, or day after) and mortality at 30 days from admission. We compared time trends in the periods 2003-2007 and 2007-2011 (before and after the launch of the NHFD), using Poisson regression models to adjust for demographic changes. FINDINGS: The number of hospitals participating in the NHFD increased from 11 in 2007 to 175 in 2011. From 2007 to 2011, the rate of early surgery increased from 54.5% to 71.3%, whereas the rate had remained stable over the period 2003-2007. Thirty-day mortality fell from 10.9% to 8.5%, compared with a small reduction from 11.5% to 10.9% previously. The annual relative reduction in adjusted 30-day mortality was 1.8% per year in the period 2003-2007, compared with 7.6% per year over 2007-2011 (P<0.001 for the difference). INTERPRETATION: The launch of a national clinician-led audit initiative was associated with substantial improvements in care and survival of older people with hip fracture in England

Search for a bound di-neutron by comparing 3^3He(e,e'p)d and 3^3H(e,e'p)X measurements

We report on a search for a bound di-neutron by comparing electron-induced proton-knockout $(e,e'p)$ measurements from Helium-3 ($^3$He) and Tritium ($^3$H). The measurements were performed at Jefferson Lab Hall A with a 4.326 GeV electron beam, and kinematics of large momentum transfer $Q^2 \approx 1.9$ (GeV/$c$)$^2$ and $x_B>1$, to minimize contributions from non quasi-elastic (QE) reaction mechanisms. Analyzing the measured $^3$He missing mass ($M_{miss}$) and missing energy ($E_{miss}$) distributions, we can distinguish the two-body break-up reaction, in which the residual proton-neutron system remains bound as a deuteron. In the $^3$H mirror case, under the exact same kinematic conditions, we do not identify a signature for a bound di-neutron with similar binding energy to that of the deuteron. We calculate exclusion limits as a function of the di-neutron binding energy and find that, for binding equivalent to the deuteron, the two-body break-up cross section on $^3$H is less than 0.9% of that on $^3$He in the measured kinematics at the 95% confidence level.Comment: 6 pages, 3 figure