Manganese Carbonyl Complexes as Selective Electrocatalysts for CO2 Reduction in Water and Organic Solvents

[Image: see text] The electrochemical reduction of CO(2) provides a way to sustainably generate carbon-based fuels and feedstocks. Molecular CO(2) reduction electrocatalysts provide tunable reaction centers offering an approach to control the selectivity of catalysis. Manganese carbonyl complexes, based on [Mn(bpy)(CO)(3)Br] and its derivatives (bpy = 2,2′-bipyridine), are particularly interesting due to their ease of synthesis and the use of a first-row earth-abundant transition metal. [Mn(bpy)(CO)(3)Br] was first shown to be an active and selective catalyst for reducing CO(2) to CO in organic solvents in 2011. Since then, manganese carbonyl catalysts have been widely studied with numerous reports of their use as electrocatalysts and photocatalysts and studies of their mechanism. This class of Mn catalysts only shows CO(2) reduction activity with the addition of weak Brønsted acids. Perhaps surprisingly, early reports showed increased turnover frequencies as the acid strength is increased without a loss in selectivity toward CO evolution. It may have been expected that the competing hydrogen evolution reaction could have led to lower selectivity. Inspired by these works we began to explore if the catalyst would work in protic solvents, namely, water, and to explore the pH range over which it can operate. Here we describe the early studies from our laboratory that first demonstrated the use of manganese carbonyl complexes in water and then go on to discuss wider developments on the use of these catalysts in water, highlighting their potential as catalysts for use in aqueous CO(2) electrolyzers. Key to the excellent selectivity of these catalysts in the presence of Brønsted acids is a proton-assisted CO(2) binding mechanism, where for the acids widely studied, lower pK(a) values actually favor CO(2) binding over Mn–H formation, a precursor to H(2) evolution. Here we discuss the wider literature before focusing on our own contributions in validating this previously proposed mechanism through the use of vibrational sum frequency generation (VSFG) spectroelectrochemistry. This allowed us to study [Mn(bpy)(CO)(3)Br] while it is at, or near, the electrode surface, which provided a way to identify new catalytic intermediates and also confirm that proton-assisted CO(2) binding operates in both the “dimer” and primary (via [Mn(bpy)(CO)(3)](−)) pathways. Understanding the mechanism of how these highly selective catalysts operate is important as we propose that the Mn complexes will be valuable models to guide the development of new proton/acid tolerant CO(2) reduction catalysts

A Manganese Complex on a Gas Diffusion Electrode for Selective CO2 to CO Reduction

Manganese carbonyl complexes have been studied extensively in solution as low cost, selective electrocatalysts with a low overpotential for CO2 reduction but experiments are typically at low current densities. In...</jats:p

Quantitative proteomics of plasma vesicles identify novel biomarkers for Hemoglobin E/ β-Thalassemic patients

Key PointsChaperones, antioxidants, iron-sequestering proteins, and cathepsin S exhibited increased abundance in thalassemic EVs. Haptoglobin and hemopexin are reduced in thalassemic patients’ EVs, reflecting hemolysis. These could be used as clinical biomarkers.</jats:p

Frontline bortezomib, rituximab, cyclophosphamide, doxorubicin, and prednisone (VR-CAP) versus rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone (R-CHOP) in transplantation-ineligible patients with newly diagnosed mantle cell lymphoma: final overall survival results of a randomised, open-label, phase 3 study

In the LYM-3002 study, the efficacy and safety of frontline bortezomib plus rituximab, cyclophosphamide, doxorubicin, and prednisone (VR-CAP) and rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone (R-CHOP) were compared in transplant-ineligible patients with untreated, newly diagnosed, mantle cell lymphoma. We report the final overall survival and safety outcomes for patients in the long-term follow-up phase after the primary progression-free-survival endpoint was met.LYM-3002 was a randomised, open-label, phase 3 study done at 128 clinical centres in 28 countries in Asia, Europe, North America, and South America. Adult patients with confirmed stage II-IV previously untreated mantle cell lymphoma, Eastern Cooperative Oncology Group performance status score of 2 or less, who were ineligible for bone marrow transplantation, were randomly assigned (1:1) to receive six or eight 21-day cycles of VR-CAP (intravenous rituximab 375 mg/m2, cyclophosphamide 750 mg/m2, doxorubicin 50 mg/m2, and bortezomib 1·3 mg/m2, plus oral prednisone 100 mg/m2) or R-CHOP (intravenous vincristine 1·4 mg/m2 [2 mg maximum], rituximab 375 mg/m2, cyclophosphamide 750 mg/m2, and doxorubicin 50 mg/m2, plus oral prednisone 100 mg/m2). Randomisation was done according to a computer-generated randomisation schedule prepared by the sponsor; permuted blocks central randomisation was used (block size of 4), and was stratified by International Prognostic Index score and disease stage at diagnosis. The primary endpoint of this final analysis was overall survival, which was analysed in the intention-to-treat population. This study is registered with ClinicalTrials.gov, number NCT00722137, and is closed to new participants with follow-up completed.Between May 22, 2008, and Dec 5, 2011, 487 patients were enrolled and randomly assigned. 268 patients (140 in the VR-CAP group and 128 in the R-CHOP group) were included in the follow-up analysis, which included patients with data available after the primary analysis clinical cutoff date of Dec 2, 2013. After median follow-up of 82·0 months (IQR 74·1-94·2), median overall survival was significantly longer in the VR-CAP group than in the R-CHOP group (90·7 months [95% CI 71·4 to not estimable] vs 55·7 months [47·2 to 68·9]; hazard ratio 0·66 [95% CI 0·51-0·85]; p=0·001). Three new adverse events were reported since the primary analysis cutoff (one each of grade 4 lung adenocarcinoma and grade 4 gastric cancer in the VR-CAP group, and one case of grade 2 pneumonia in the R-CHOP group). 103 (42%) of 243 patients in the VR-CAP group, and 138 (57%) of 244 in the R-CHOP group died; the most common cause of death was progressive disease.Compared with R-CHOP, VR-CAP was associated with significantly longer survival, and had a manageable and expected safety profile. Our results support further assessment of VR-CAP in patients with previously untreated mantle cell lymphoma.Janssen Research & Development

Zero-Gap Bipolar Membrane Electrolyzer for Carbon DioxideReduction Using Acid-Tolerant Molecular Electrocatalysts

[Image: see text] The scaling-up of electrochemical CO(2) reduction requires circumventing the CO(2) loss as carbonates under alkaline conditions. Zero-gap cell configurations with a reverse-bias bipolar membrane (BPM) represent a possible solution, but the catalyst layer in direct contact with the acidic environment of a BPM usually leads to H(2) evolution dominating. Here we show that using acid-tolerant Ni molecular electrocatalysts selective (>60%) CO(2) reduction can be achieved in a zero-gap BPM device using a pure water and CO(2) feed. At a higher current density (100 mA cm(–2)), CO selectivity decreases, but was still >30%, due to reversible product inhibition. This study demonstrates the importance of developing acid-tolerant catalysts for use in large-scale CO(2) reduction devices

Glutathione Redox System in β

β-thalassemia/Hb E is known to cause oxidative stress induced by iron overload. The glutathione system is the major endogenous antioxidant that protects animal cells from oxidative damage. This study aimed to determine the effect of disease state and splenectomy on redox status expressed by whole blood glutathione (GSH)/glutathione disulfide (GSSG) and also to evaluate glutathione-related responses to oxidation in β-thalassemia/Hb E patients. Twenty-seven normal subjects and 25 β-thalassemia/Hb E patients were recruited and blood was collected. The GSH/GSSG ratio, activities of glutathione-related enzymes, hematological parameters, and serum ferritin levels were determined in individuals. Patients had high iron-induced oxidative stress, shown as significantly increased serum ferritin, a decreased GSH/GSSG ratio, and increased activities of glutathione-related enzymes. Splenectomy increased serum ferritin levels and decreased GSH levels concomitant with unchanged glutathione-related enzyme activities. The redox ratio had a positive correlation with hemoglobin levels and negative correlation with levels of serum ferritin. The glutathione system may be the body’s first-line defense used against oxidative stress and to maintain redox homeostasis in thalassemic patients based on the significant correlations between the GSH/GSSH ratio and degree of anemia or body iron stores

Potential Dependent Reorientation Controlling Activity of a Molecular Electrocatalyst.

The activity of molecular electrocatalysts depends on the interplay of electrolyte composition near the electrode surface, the composition and morphology of the electrode surface, and the electric field at the electrode-electrolyte interface. This interplay is challenging to study and often overlooked when assessing molecular catalyst activity. Here, we use surface specific vibrational sum frequency generation (VSFG) spectroscopy to study the solvent and potential dependent activation of Mo(bpy)(CO)4, a CO2 reduction catalyst, at a polycrystalline Au electrode. We find that the parent complex undergoes potential dependent reorientation at the electrode surface when a small amount of N-methyl-2-pyrrolidone (NMP) is present. This preactivates the complex, resulting in greater yields at less negative potentials, of the active electrocatalyst for CO2 reduction

Bortezomib-based therapy for newly diagnosed mantle-cell lymphoma

Background: the proteasome inhibitor bortezomib was initially approved for the treatment of relapsed mantle-cell lymphoma. We investigated whether substituting bortezomib for vincristine in frontline therapy with R-CHOP (rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone) could improve outcomes in patients with newly diagnosed mantle-cell lymphoma. Methods: in this phase 3 trial, we randomly assigned 487 adults with newly diagnosed mantle-cell lymphoma who were ineligible or not considered for stem-cell transplantation to receive six to eight 21-day cycles of R-CHOP intravenously on day 1 (with prednisone administered orally on days 1 to 5) or VR-CAP (R-CHOP regimen, but replacing vincristine with bortezomib at a dose of 1.3 mg per square meter of body-surface area on days 1, 4, 8, and 11). The primary end point was progression-free survival. Results: after a median follow-up of 40 months, median progression-free survival (according to independent radiologic review) was 14.4 months in the R-CHOP group versus 24.7 months in the VR-CAP group (hazard ratio favoring the VR-CAP group, 0.63; P<0.001), a relative improvement of 59%. On the basis of investigator assessment, the median durations of progression-free survival were 16.1 months and 30.7 months, respectively (hazard ratio, 0.51; P<0.001), a relative improvement of 96%. Secondary end points were consistently improved in the VR-CAP group, including the complete response rate (42% vs. 53%), the median duration of complete response (18.0 months vs. 42.1 months), the median treatment-free interval (20.5 months vs. 40.6 months), and the 4-year overall survival rate (54% vs. 64%). Rates of neutropenia and thrombocytopenia were higher in the VR-CAP group. Conclusions: VR-CAP was more effective than R-CHOP in patients with newly diagnosed mantle-cell lymphoma but at the cost of increased hematologic toxicity. (Funded by Janssen Research and Development and Millennium Pharmaceuticals; LYM-3002 ClinicalTrials.gov number, NCT00722137)

First principles high throughput screening of oxynitrides for water-splitting photocatalysts

In this paper, we present a first principles high throughput screening system to search for new water-splitting photocatalysts. We use the approach to screen through nitrides and oxynitrides. Most of the known photocatalytic materials in the screened chemical space are reproduced. In addition, sixteen new materials are suggested by the screening approach as promising photocatalysts, including three binary nitrides, two ternary oxynitrides and eleven quaternary oxynitrides.United States. Dept. of Energy (contract DE-FG02-96ER4557)National Science Foundation (U.S.) (TeraGrid resources under Grant No. TG-DMR970008S)Pittsburgh Supercomputing CenterUniversity of Texas at Austin. Texas Advanced Computing CenterEni-MIT Solar Frontiers Cente