Unprecedented spin localisation in a metal-metal bonded dirhenium complex

he molecular and electronic structure of edge-sharing bioctahedral [N(n-Bu)4]3[Re2(mnt)5] is reported here. Despite the short intermetal bond length of 2.6654(2) Å with computed bond order of 1.2, the unpaired electron is localised by the asymmetric ligand distribution, as demonstrated by its remarkable EPR spectrum

Expanding the scope of ligand substitution from [M(S2C2Ph2] (M = Ni2+, Pd2+, Pt2+) to afford new heteroleptic dithiolene complexes

The scope of direct substitution of the dithiolene ligand from [M(S2C2Ph2)2] [M = Ni2+ (1), Pd2+ (2), Pt2+ (3)] to produce heteroleptic species [M(S2C2Ph2)2Ln] (n = 1, 2) has been broadened to include isonitriles and dithiooxamides in addition to phosphines and diimines. Collective observations regarding ligands that cleanly produce [M(S2C2Ph2)Ln], do not react at all, or lead to ill-defined decomposition identify soft σ donors as the ligand type capable of dithiolene substitution. Substitution of MeNC from [Ni(S2C2Ph2)(CNMe)2] by L provides access to a variety of heteroleptic dithiolene complexes not accessible from 1. Substitution of a dithiolene ligand from 1 involves net redox disproportionation of the ligands from radical monoanions, –S•SC2Ph2, to enedithiolate and dithione, the latter of which is an enhanced leaving group that is subject to further irreversible reactions

Ligand radicals as modular organic electron spin qubits

The intrinsic redox activity of the dithiolene ligand is presented here as the novel spin host in the design of prototype molecular electron spin qubit where the traditional roles of the metal and ligand components in coordination complexes are inverted. A series of paramagnetic bis(dithiolene) complexes with group 10 metals – nickel, palladium, platinum – provides a backdrop to investigate the spin dynamics of the organic ligand radical using pulsed EPR spectroscopy. The temperature dependence of the phase memory time (TM) is shown to be dependent on the identity of the diamagnetic metal ion with the short times recorded for platinum a consequence of a diminishing spin‐lattice (T1) relaxation time driven by spin‐orbit coupling. The utility of the radical ligand spin center is confirmed when it delivers one of the longest phase memory times ever recorded for a molecular two‐qubit prototype

Efficacy and Safety of Alirocumab as Add-on Therapy in High–Cardiovascular-Risk Patients With Hypercholesterolemia Not Adequately Controlled With Atorvastatin (20 or 40 mg) or Rosuvastatin (10 or 20 mg)::Design and Rationale of the ODYSSEY OPTIONS Studies

The phase 3 ODYSSEY OPTIONS studies (OPTIONS I, NCT01730040; OPTIONS II, NCT01730053) are multicenter, multinational, randomized, double-blind, active-comparator, 24-week studies evaluating the efficacy and safety of alirocumab, a fully human monoclonal antibody targeting proprotein convertase subtilisin/kexin type 9, as add-on therapy in ∼ 650 high-cardiovascular (CV)-risk patients whose low-density lipoprotein cholesterol (LDL-C) levels are ≥100 mg/dL or ≥70 mg/dL according to the CV-risk category, high and very high CV risk, respectively, with atorvastatin (20–40 mg/d) or rosuvastatin (10–20 mg/d). Patients are randomized to receive alirocumab 75 mg via a single, subcutaneous, 1-mL injection by prefilled pen every 2 weeks (Q2W) as add-on therapy to atorvastatin (20–40 mg) or rosuvastatin (10–20 mg); or to receive ezetimibe 10 mg/d as add-on therapy to statin; or to receive statin up-titration; or to switch from atorvastatin to rosuvastatin (OPTIONS I only). At week 12, based on week 8 LDL-C levels, the alirocumab dose may be increased from 75 mg to 150 mg Q2W if LDL-C levels remain ≥100 mg/dL or ≥70 mg/dL in patients with high or very high CV risk, respectively. The primary efficacy endpoint in both studies is difference in percent change in calculated LDL-C from baseline to week 24 in the alirocumab vs control arms. The studies may provide guidance to inform clinical decision-making when patients with CV risk require additional lipid-lowering therapy to further reduce LDL-C levels. The flexibility of the alirocumab dosing regimen allows for individualized therapy based on the degree of LDL-C reduction required to achieve the desired LDL-C level

Long-term Performance of ‘Delicious’ Apple Trees Grafted on Geneva® Rootstocks and Trained to Four High-density Systems under New York State Climatic Conditions

We conducted a large (0.8 ha) field experiment of system × rootstock, using Super Chief Delicious apple as cultivar at Yonder farm in Hudson, NY, between 2007 and 2017. In this study, we compared six Geneva® rootstocks (‘G.11’, ‘G.16’, ‘G.210’, ‘G.30’, ‘G.41’, and ‘G.935’) with one Budagovsky (‘B.118’) and three Malling rootstocks (‘M.7EMLA’, ‘M.9T337’ and ‘M.26EMLA’). Trees on each rootstock were trained to four high-density systems: Super Spindle (SS) (5382 apple trees/ha), Tall Spindle (TS) (3262 apple trees/ha), Triple Axis Spindle (TAS) (2243 apple trees/ha), and Vertical Axis (VA) (1656 apple trees/ha). Rootstock and training system interacted to influence growth, production, and fruit quality. When comparing systems, SS trees were the least vigorous but much more productive on a per hectare basis. Among the rootstocks we evaluated, ‘B.118’ had the largest trunk cross-sectional area (TCSA), followed by ‘G.30’ and ‘M.7EMLA’, which were similar in size but they did not differ statistically from ‘G.935’. ‘M.9T337’ was the smallest and was significantly smaller than most of the other rootstocks but it did not differ statistically from ‘G.11’, ‘G.16’, ‘G.210’, ‘G.41’, and ‘M.26EMLA’. Although ‘B.118’ trees were the largest, they had low productivity, whereas the second largest rootstock ‘G.30’ was the most productive on a per hectare basis. ‘M.9’ was the smallest rootstock and failed to adequately fill the space in all systems except the SS, and had low cumulative yield. The highest values for cumulative yield efficiency (CYE) were with ‘G.210’ for all training systems except for VA, where ‘M.9T337’ had the highest value. The lowest values were for all training systems with ‘B.118’ and ‘M.7EMLA’. Regardless of the training system, ‘M.7EMLA’ trees had the highest number of root suckers. Some fruit quality traits were affected by training system, rootstock or system × rootstock combination.info:eu-repo/semantics/publishedVersio

The analysis of para-cresol production and tolerance in Clostridium difficile 027 and 012 strains

<p>Abstract</p> <p>Background</p> <p><it>Clostridium difficile </it>is the major cause of antibiotic associated diarrhoea and in recent years its increased prevalence has been linked to the emergence of hypervirulent clones such as the PCR-ribotype 027. Characteristically, <it>C. difficile </it>infection (CDI) occurs after treatment with broad-spectrum antibiotics, which disrupt the normal gut microflora and allow <it>C. difficile </it>to flourish. One of the relatively unique features of <it>C. difficile </it>is its ability to ferment tyrosine to <it>para</it>-cresol via the intermediate <it>para</it>-hydroxyphenylacetate (<it>p-</it>HPA). <it>P</it>-cresol is a phenolic compound with bacteriostatic properties which <it>C. difficile </it>can tolerate and may provide the organism with a competitive advantage over other gut microflora, enabling it to proliferate and cause CDI. It has been proposed that the <it>hpdBCA </it>operon, rarely found in other gut microflora, encodes the enzymes responsible for the conversion of <it>p-</it>HPA to <it>p</it>-cresol.</p> <p>Results</p> <p>We show that the PCR-ribotype 027 strain R20291 quantitatively produced more <it>p</it>-cresol <it>in-vitro </it>and was significantly more tolerant to <it>p</it>-cresol than the sequenced strain 630 (PCR-ribotype 012). Tyrosine conversion to <it>p</it>-HPA was only observed under certain conditions. We constructed gene inactivation mutants in the <it>hpdBCA </it>operon in strains R20291 and 630Δ<it>erm </it>which curtails their ability to produce <it>p</it>-cresol, confirming the role of these genes in <it>p-</it>cresol production. The mutants were equally able to tolerate <it>p</it>-cresol compared to the respective parent strains, suggesting that tolerance to <it>p</it>-cresol is not linked to its production.</p> <p>Conclusions</p> <p><it>C. difficile </it>converts tyrosine to <it>p</it>-cresol, utilising the <it>hpdBCA </it>operon in <it>C. difficile </it>strains 630 and R20291. The hypervirulent strain R20291 exhibits increased production of and tolerance to <it>p-</it>cresol, which may be a contributory factor to the virulence of this strain and other hypervirulent PCR-ribotype 027 strains.</p

Redox-active metallodithiolene groups separated by insulating tetraphosphinobenzene spacers

Compounds of the type [(S2C2R2)M(μ-tpbz)M(S2C2R2)] (R = CN, Me, Ph, p-anisyl; M = Ni, Pd, Pt; tpbz = 1,2,4,5-tetrakis(diphenylphosphino)benzene) have been prepared by transmetalation with [(S2C2R2)SnR′2] reagents, by direct displacement of dithiolene ligand from [M(S2C2R2)2] with 0.5 equiv of tpbz, or by salt metathesis using Na2[S2C2(CN)2] in conjunction with X2M(μ-tpbz)MX2 (X = halide). X-ray crystallography reveals a range of topologies (undulating, chair, bowed) for the (S2C2)M(P2C6P2)M(S2C2) core. The [(S2C2R2)M(μ-tpbz)M(S2C2R2)] (R = Me, Ph, p-anisyl) compounds support reversible or quasireversible oxidations corresponding to concurrent oxidation of the dithiolene terminal ligands from ene-1,2-dithiolates to radical monoanions, forming [(−S•SC2R2)M(μ-tpbz)M(−S•SC2R2)]2+. The R = Ph and p-anisyl compounds support a second, reversible oxidation of the dithiolene ligands to their α-dithione form. In contrast, [(S2C2(CN)2)Ni(tpbz)Ni(S2C2(CN)2)] sustains only reversible, metal-centered reductions. Spectroscopic examination of [(−S•SC2(p-anisyl)2)Ni(μ-tpbz)Ni(−S•SC2(p-anisyl)2)]2+ by EPR reveals a near degenerate singlet–triplet ground state, with spectral simulation revealing a remarkably small dipolar coupling constant of 18 × 10–4 cm–1 that is representative of an interspin distance of 11.3 Å. This weak interaction is mediated by the rigid tpbz ligand, whose capacity to electronically insulate is an essential quality in the development of molecular-based spintronic devices

Group 10 metal dithiolene bis(isonitrile) complexes: synthesis, structures, properties and reactivity

The reaction of [(Ph2C2S2)2M] (M = Ni2+, Pd2+, Pt2+) with 2 equiv of RN≡C (R = Me (a), Bn (b), Cy (c), tBu (d), 1-Ad (e), Ph (f)) yields [(Ph2C2S2)M(C≡NR)2] (M = Ni2+, 4a–f; M = Pd2+, 5a–f; M = Pt2+, 6a–f), which are air-stable and amenable to chromatographic purification. All members have been characterized crystallographically. Structurally, progressively greater planarity tends to be manifested as M varies from Ni to Pt, and a modest decrease in the C≡N bond length of coordinated C≡NR appears in moving from Ni toward Pt. Vibrational spectroscopy (CH2Cl2 solution) reveals νC≡N frequencies for [(Ph2C2S2)M(C≡NR)2] that are substantially higher than those for free C≡NR and increase as M ranges from Ni to Pt. This trend is interpreted as arising from an increasingly positive charge at M that stabilizes the linear, charge-separated resonance form of the ligand over the bent form with lowered C–N bond order. UV–vis spectra reveal lowest energy transitions that are assigned as HOMO (dithiolene π) → LUMO (M–L σ*) excitations. One-electron oxidations of [(Ph2C2S2)M(C≡NR)2] are observed at ∼+0.5 V due to Ph2C2S22– → Ph2C2S–S• + e–. Chemical oxidation of [(Ph2C2S2)Pt(C≡NtBu)2] with [(Br-p-C6H4)3N][SbCl6] yields [(Ph2C2S–S•)Pt(C≡NtBu)2]+, identified spectroscopically, but in the crystalline state [[(Ph2C2S–S•)Pt(C≡NtBu)2]2]2+ prevails, which forms via axial Pt···S interactions and pyramidalization at the metal. Complete substitution of MeNC from [(Ph2C2S2)Ni(C≡NMe)2] by 2,6-Me2py under forcing conditions yields [(2,6-Me2py)Ni(μ2-η1,η1-S′,η1-S″-S2C2Ph2)]2 (8), which features a folded Ni2S2 core. In most cases, isocyanide substitution from [(Ph2C2S2)M(C≡NMe)2] with monodentate ligands (L = phosphine, CN–, carbene) leads to [(Ph2C2S2)M(L)(C≡NMe)]n (n = 0, 1−), wherein νC≡N varies according to the relative σ-donating power of L (9–21). The use of 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene (IPr) provides [(Ph2C2S2)M(IPr)(C≡NMe)] for M = Ni (18), Pd (19), but for Pt, attack by IPr at the isocyanide carbon occurs to yield the unusual η1,κC-ketenimine complex [(Ph2C2S2)Pt(C(NMe)(IPr))(C≡NMe)] (20)

Effect of tree type and rootstock on the long-term performance of ‘Gala’, ‘Fuji’ and ‘Honeycrisp’ apple trees trained to Tall Spindle under New York State climatic conditions

In 2006, two 0.3 ha orchard trials were established at two sites (Dressel farm in Southeastern New York State and VandeWalle farm in Western New York State) to compare two tree types (feathered trees and bench-grafted trees) on five rootstocks [three Geneva® rootstocks (G.11, G.16, G.41) with one Budagovsky rootstock (B.9) and one Malling rootstock (M.9T337)] as controls. ‘Gala’ and ‘Fuji’ were used as scion cultivars at Dressel farm and ‘Gala’ and ‘Honeycrisp’ as the scions cultivars at VandeWalle farm. At each location, trees were planted at 3,262 trees ha−1and trained to a Tall Spindle (TS) system. Location, tree type and rootstock interacted to affect tree growth, production and fruit quality of each scion cultivar. ‘Gala’ trees from VandeWalle (Western NY State) were more productive (33% more production) than those from Dressel Farm (Southern NY State), because they produced more fruits per cm−2 and fruit size was bigger. When comparing the two tree types (feathered and bench-grafted) at both locations and across all rootstocks (B.9, G.11, G.16, G.41, and M.9T337), feathered trees were similar in tree size after 11 seasons as bench-grafted ones, except for ‘Fuji’ at Dressel farm where bench-grafted trees were 27% smaller than feathered trees. The bench-grafted trees had lower cumulative yield per hectare, cumulative yield efficiency, and cumulative crop load than the fully feathered trees. Finally, when comparing all 10 tree type × rootstock combinations, for ‘Fuji’, feathered trees with G.11, for ‘Gala’, feathered trees with G.41, and for ‘Honeycrisp’, feathered trees with G.16 were the combinations with the highest cumulative yield, high yield efficiency and crop loads, low biennial bearing, and with slightly significant larger fruits.info:eu-repo/semantics/acceptedVersio