Crystal structure of catena-poly[[(μ-6-{[bis­­(pyridin-2-ylmeth­yl)amino]­meth­yl}pyridine-2-carboxyl­ato)copper(II)] perchlorate aceto­nitrile monosolvate]

The crystal structure of the title compound, {[Cu(C19H17N4O2)]ClO4·C2H3N}n, is reported and compared to similar structures in the literature. The compound crystallizes in the monoclinic space group P21. The unit cell contains one complex mol­ecule in addition to perchlorate as the counter-ion and solvent (aceto­nitrile). The crystal packing evinces extended chains whereby the carboxyl­ate moiety on the 6-carboxyl­ato-2-(pyridyl­meth­yl)bis­(pyridin-2-ylmeth­yl)amine ligand bridges between two different copper centers in adjacent mol­ecules. This packing arrangement for the title compound appears to be unique when compared to allied structures in the literature. The perchlorate anion showed signs of disorder and its oxygen atoms were modelled over two sets of partially occupied sites, the occupancy of which was competitively refined to 0.564 (12)/0.436 (12). The crystal studied was refined as a two-component inversion twin

Proton-coupled electron transfer enhances the electrocatalytic reduction of nitrite to NO in a bioinspired copper complex

This work was supported by the EPSRC (Grant No. EP/ K031732/1) and the Royal Society (University Research Fellowship UF150104 to M.D.S.). The data which underpin this work are available at http://dx.doi.org/10.5525/gla. researchdata.590 and are available under a CC-BY licence.The selective and efficient electrocatalytic reduction of nitrite to nitric oxide (NO) is of tremendous importance, both for the development of NO-release systems for biomedical applications and for the removal of nitrogen oxide pollutants from the environment. In nature, this transformation is mediated by (among others) enzymes known as the copper-containing nitrite reductases. The development of synthetic copper complexes that can reduce nitrite to NO has therefore attracted considerable interest. However, there are no studies describing the crucial role of proton-coupled electron transfer during nitrite reduction when such synthetic complexes are used. Herein, we describe the synthesis and characterization of two previously unreported Cu complexes ( 3 and 4 ) for the electrocatalytic reduction of nitrite to NO, in which the role of proton-relaying units in the secondary coordination sphere of the metal can be probed. Complex 4 bears a pendant carboxylate group in close proximity to the copper center, while complex 3 lacks such functionality. Our results suggest that complex 4 is twice as effective an electrocatalyst for nitrite reduction than is complex 3 and that complex 4 is the best copper-based molecular electrocatalyst for this reaction yet discovered. The differences in reactivity between 3 and 4 are probed using a range of electrochemical, spectroscopic, and computational methods, which shed light on the possible catalytic mechanism of 4 and implicate the proton-relaying ability of its pendant carboxylate group in the enhanced reactivity that this complex displays. These results highlight the critical role of proton-coupled electron transfer in the reduction of nitrite to NO and have important implications for the design of biomimetic catalysts for the selective interconversions of the nitrogen oxides.Publisher PDFPeer reviewe

Ligand-directed synthesis of {MnIII5} twisted bow-ties

Two isostructural polymetallic complexes [MnIII5(μ3-O)2(CH3COO)4(L1)4]− and [MnIII5(μ3-O)2(CH3COO)4(L2)4]− have been synthesised by using two Schiff base ligands derived from 3,5-diamino-1,2,4-triazole, following two different preparative routes, either using the pre-formed ligand (for L1) or via a metal-mediated template synthesis (for L2). The {MnIII5} structure is unusual, being based on two corner-sharing perpendicular {Mn3} triangles forming a twisted bow-tie. The magnetic studies reveal antiferromagnetic coupling between Mn(iii) ions while electrochemical experiments are consistent with a quasi-reversible Mn(iii)↔Mn(iv) redox process at the central manganese ion

Toward decentralized nitrogen fixation using pulsed ultrasound

Current anthropogenic nitrogen fixation routes leave very little scope for the production of fertilizers in small, decentralized facilities close to the point of use. Such decentralized production would require nitrogen fixation without the need for high-temperature or high-pressure reactors, using only air and water, and without any additional reagents. Here, we report a nitrogen fixation approach that meets all of these criteria: fixation using ultrasound. Through the optimization of various acoustic parameters, we demonstrate that nitrate solutions of approximately 15 μM can be produced by applying just 60 s of pulsed ultrasound at 200 kHz to an air/water mixture at room temperature. These results constitute a record rate of production of nitrogen oxides by sonication in aqueous solution and are a step change in terms of energy requirements per mole of products relative to previous reports. This simple approach could have potential for low-capital-cost, decentralized nitrogen fixation in areas where infrastructure is lacking

Ligand-directed synthesis of {MnIII5} twisted bow-ties

Two isostructural polymetallic complexes [MnIII5(μ3-O)2(CH3COO)4(L1)4]− and [MnIII5(μ3-O)2(CH3COO)4(L2)4]− have been synthesised by using two Schiff base ligands derived from 3,5-diamino-1,2,4-triazole, following two different preparative routes, either using the pre-formed ligand (for L1) or via a metal-mediated template synthesis (for L2). The {MnIII5} structure is unusual, being based on two corner-sharing perpendicular {Mn3} triangles forming a twisted bow-tie. The magnetic studies reveal antiferromagnetic coupling between Mn(III) ions while electrochemical experiments are consistent with a quasi-reversible Mn(III)↔Mn(IV) redox process at the central manganese ion

Is it possible to accurately predict outcome of a drop-foot in patients admitted to a hospital stroke unit?

The aim of this study was to determine whether recovery from a drop-foot at 6 months can be predicted within 72 h after stroke and to investigate the effect of timing on the accuracy of prediction. One hundred and five patients with a first-ever anterior circulation stroke without full voluntary ankle dorsiflexion in standing position following the Fugl-Meyer motor score at 72 h were included for further analysis. Determinants were measured within 72 h, and at days 5 and 9 after stroke onset. Multivariable logistic regression analysis was used to predict the recovery of full ankle dorsiflexion while standing at 6 months. Having the item 'Motricity Index ankle dorsiflexion 19 or more (full range of motion ankle dorsiflexion againsts gravity)' was the best predictive variable. The sensitivity was 0.74 [95% confidence interval (CI) 0.62-0.80], specificity was 0.72 (95% CI 0.62-0.81), positive predictive value was 0.74 (95% CI 0.63-0.82), and negative predictive value was 0.71 (95% CI 0.60-0.80). No significant changes at day 5 and 9 after stroke were found. In stroke patients, the presence of full ankle dorsiflexion against gravity within 72 h is an accurate predictor for the absence of a drop-foot at 6 months. The accuracy of prediction of true positives and negatives is irrespective of the time of assessment in a stroke unit. © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins

A soft robotic extra-finger and arm support to recover grasp capabilities in chronic stroke patients

In this paper, we present the combination of the Soft-SixthFinger, a wearable robotic extra-finger designed to be used by chronic stroke patients to compensate for the missing hand function, with a robotic arm that is used as an assistive device to support the patient arm. The extra-finger is a tendon-driven modular structure worn at the paretic forearm. The robotic extra-finger is used jointly with the paretic hand/arm to grasp an object similarly to the two parts of a robotic gripper. The flexion/extension of the robotic finger is controlled by the patient using an Electromyography (EMG) interface embedded in a cap. The robotic arm is controlled to partially compensate for the weight of the paretic arm, while not interfering with the user arm motion. The system has been designed as a tool that can be used by chronic stroke patients to compensate for grasping in many Activities of Daily Living (ADL). We performed a pilot test to demonstrate that the proposed system can significantly improve the performance and the autonomy in ADL

Crystal structure of <i>catena</i>-poly[[(μ-6-{[bis(pyridin-2-ylmethyl)amino]methyl}pyridine-2-carboxylato)copper(II)] perchlorate acetonitrile monosolvate]

The crystal structure of the title compound, {[Cu(C19H17N4O2)]ClO4·C2H3N} n , is reported and compared to similar structures in the literature. The compound crystallizes in the monoclinic space group P21. The unit cell contains one complex molecule in addition to perchlorate as the counter-ion and solvent (acetonitrile). The crystal packing evinces extended chains whereby the carboxylate moiety on the 6-carboxylato-2-(pyridylmethyl)bis(pyridin-2-ylmethyl)amine ligand bridges between two different copper centers in adjacent molecules. This packing arrangement for the title compound appears to be unique when compared to allied structures in the literature. The perchlorate anion showed signs of disorder and its oxygen atoms were modelled over two sets of partially occupied sites, the occupancy of which was competitively refined to 0.564 (12)/0.436 (12). The crystal studied was refined as a two-component inversion twin.</jats:p